Slabs & Patios
Estimate concrete for backyard pads, patios, sheds and general rectangular flatwork.
Driveways
Convert driveway dimensions into cubic yards before requesting supplier quotes.
Footings
Calculate long rectangular footing or wall sections from finished dimensions.
Round Piers
Estimate cylindrical concrete for posts, piers and round support foundations.
Concrete Calculator in Greensboro
A Concrete Calculator in Greensboro helps homeowners, contractors, estimators and property managers convert real project dimensions into concrete volume before ordering materials. The basic objective is straightforward: calculate how many cubic feet the planned shape occupies, convert that volume to cubic yards for ready-mix ordering, and add a realistic allowance for field variation.
This page is designed around common Greensboro concrete projects such as patios, driveway sections, sidewalks, equipment pads, footings and round piers. It also includes local planning information so the quantity estimate is not treated as a substitute for permits, drainage review, inspections or structural design.
The Greensboro jurisdiction maintains a Building Department that handles permit issuance, plan review and inspections. The applicable local jurisdiction also provides a local permit portal for online permit applications and records. Before beginning work that may require approval, verify the current requirements for your property and scope.
How the Greensboro Concrete Calculator Works
The calculator begins with geometry. A rectangular slab uses length × width × thickness. A footing or wall uses length × width × depth. A round pier uses π × radius squared × depth. Every result is first calculated as exact geometric volume.
The tool then converts exact volume to cubic yards and cubic meters. If you select an ordering allowance, that percentage is added separately so you can see the difference between the measured project and the order-planning quantity.
Convert thickness from inches to feet before multiplying when using feet.
Radius is one-half of diameter.
How to Use the Concrete Calculator in Greensboro
- Select the project type. Choose slab/patio, driveway/sidewalk, footing/wall or round pier/post.
- Measure finished concrete dimensions. Measure the concrete shape itself rather than the entire excavation unless the excavation will be completely filled.
- Enter thickness carefully. Flatwork thickness is entered in inches and converted automatically.
- Enter repeated quantity. Multiple identical piers or slab sections can be calculated together.
- Select an ordering allowance. Keep exact volume and extra material separate so the estimate remains easy to audit.
- Add optional price per cubic yard. This provides a basic material subtotal, not a full installed-cost quote.
- Verify permit and design requirements. Local approvals, drainage, reinforcement and structural dimensions are outside a quantity calculator.
Greensboro Concrete Slab Calculator
Concrete slabs are used for patios, equipment pads, shed bases, walkways and many other residential and commercial improvements. To calculate volume, multiply finished length by finished width and slab thickness.
For example, a 20 ft × 12 ft slab at 4 inches thick contains 80 cubic feet of concrete. Dividing by 27 gives approximately 2.96 cubic yards before any extra allowance. Selecting 10% extra would increase the order-planning quantity to about 3.26 cubic yards.
That arithmetic does not decide whether 4 inches is an appropriate thickness. Thickness can depend on use, loading, soil support, reinforcement, edge conditions and project requirements. Enter the thickness specified or otherwise established for your project.
Concrete Driveway Calculator in Greensboro
A driveway estimate uses the same rectangular volume formula as a slab, but driveways can include aprons, widened parking areas, thickened edges and transitions. Calculate those sections separately when their thickness or width differs.
Suppose a driveway section is 40 ft long, 10 ft wide and 5 inches thick. The exact volume is about 166.67 cubic feet, or 6.17 cubic yards. A 10% ordering allowance produces approximately 6.79 cubic yards.
Do not assume a driveway is one uniform rectangle if it flares near the street or garage. Divide irregular driveways into rectangles and add the results. If a curved area is significant, estimate it with suitable circular or segmented geometry.
For round or curved concrete features, use the Circular Concrete Calculator. For dedicated cubic-foot conversions, use the Concrete Cubic Foot Calculator.
Concrete Patio Calculator in Greensboro
Patios are one of the easiest projects to measure accurately when forms are installed. Measure inside form length and width, then verify depth at several locations across the prepared base. A low area in the subgrade can increase concrete consumption even when the perimeter dimensions are correct.
If the patio contains a planter opening, drain box, large utility opening or another section that will not contain concrete, calculate and subtract that void when it materially affects volume. Small penetrations can sometimes be absorbed within the ordering allowance.
Decorative borders or thickened edges should be calculated as additional non-overlapping shapes. This avoids double-counting concrete already included in the main slab.
Concrete Sidewalk and Walkway Calculator
Sidewalks and walkways are long narrow slabs. Multiply the total run length by walkway width and thickness. If the walkway changes width, divide it into separate sections rather than using an aggressive average.
Curved walkways can be approximated with multiple short rectangular sections or calculated using circular geometry when the curve follows a known radius. For quantity purposes, accuracy improves when the measurement method matches the actual layout.
Concrete joint planning is separate from volume. Use the Concrete Joint Spacing Calculator for control-joint layout and the Concrete Expansion Joint Calculator when you need material quantities for specified isolation or expansion joints.
Concrete Footing Calculator in Greensboro
Continuous footings can be estimated as long rectangular prisms. Convert footing width and depth from inches to feet, multiply by length, and then multiply by the number of identical sections.
A 40 ft footing that is 16 inches wide and 12 inches deep contains approximately 53.33 cubic feet, or 1.98 cubic yards before allowance. If the footing has steps, enlarged pads or thickened portions, calculate those separately.
Foundation dimensions are structural and geotechnical decisions. This calculator does not choose footing width, depth, reinforcement or bearing criteria.
Round Pier and Post Concrete Calculator
Round piers and post foundations use cylindrical geometry. Convert diameter to feet, divide by two for radius, square the radius, multiply by π and then multiply by depth.
An 18-inch diameter pier that is 4 ft deep contains about 7.07 cubic feet. Four identical piers total approximately 28.27 cubic feet, or about 1.05 cubic yards before allowance.
Augered holes can consume more concrete than the theoretical cylinder if soil collapses or the hole becomes wider than intended. Verify actual field dimensions before final ordering when possible. For belled or stepped piers, use the Concrete Pier Calculator.
Concrete Volume Conversion Table
| Cubic Feet | Cubic Yards | Cubic Meters | Approx. 80 lb Bags* |
|---|---|---|---|
| 10 ft³ | 0.370 yd³ | 0.283 m³ | 17 |
| 27 ft³ | 1.000 yd³ | 0.765 m³ | 45 |
| 50 ft³ | 1.852 yd³ | 1.416 m³ | 84 |
| 100 ft³ | 3.704 yd³ | 2.832 m³ | 167 |
| 135 ft³ | 5.000 yd³ | 3.823 m³ | 225 |
| 270 ft³ | 10.000 yd³ | 7.646 m³ | 450 |
*Bag count uses an approximate planning yield of 0.60 ft³ for an 80 lb bag. Always verify the yield printed by the manufacturer.
How Much Extra Concrete Should You Order in Greensboro?
The calculator offers 0%, 5%, 10% and 15% allowances. The correct choice depends on project conditions rather than city location alone. Neatly formed flatwork with a uniform base can track geometric volume closely. Irregular excavations, deep pier holes, variable base elevation and complex forms can create larger differences.
Keep the exact geometric volume visible so you know what the project dimensions require. Then choose the extra allowance separately. This is better than increasing measurements manually because it keeps the estimate transparent.
Before final ordering, verify dimensions after excavation and formwork are complete. Ready-mix suppliers may also have minimum loads, short-load policies and ordering increments that affect the final purchase quantity.
Greensboro Building Permits and Concrete Work
The City of Greensboro's Building Inspections Division provides plan review, permitting and inspections for residential and commercial construction. The City's residential-construction guidance says a building permit is required for construction that is structural in nature, for non-structural work exceeding the stated cost threshold, and for certain projects that cover new ground such as additions, accessory buildings, garages and pools.
Concrete work can range from a simple private patio to a structural foundation, driveway approach, retaining element or commercial slab. Because those projects do not all follow one permit path, use this calculator only for concrete quantity and verify the actual permit requirement for the project scope.
Greensboro also lists a separate driveway permit for driveway access to City streets. If a driveway project changes the street connection, public-side apron or access point, check the current City process before final ordering.
Building Construction & Plan Review · Residential Construction · Permits & Licenses
Greensboro Weather and Concrete Pour Planning
Greensboro concrete work can be affected by summer heat and humidity, thunderstorms, heavy rain, freezing nights and occasional winter weather. The quantity formula stays the same, but site conditions can change excavation, subgrade, truck access, placement timing, finishing and curing.
For warm-weather pours, coordinate truck spacing with the crew's actual placement rate and have curing materials ready before the first load arrives. For cold-weather placements, use the project specifications and approved cold-weather concrete procedures rather than assuming ordinary curing conditions.
Always check the current local forecast close to placement time. A multi-truck slab or driveway is much harder to pause after the pour begins than a small bagged-concrete project.
Drainage, Grading and Exterior Concrete in Greensboro
Driveways, patios, sidewalks and exterior slabs can change how runoff moves across a property. A concrete-volume calculator cannot determine the correct slope, finished elevation, stormwater path, curb transition or drainage requirement.
Greensboro publishes engineering guidelines, standard roadway and utility drawings, driveway information and stormwater resources for development work. Public-side concrete and street connections can therefore require a different review path from concrete entirely on private property.
Measure the final approved geometry before ordering. If grading, drainage or driveway-review requirements change a slab edge, apron or curb connection, update the cubic-yard estimate.
Engineering Guidelines & Publications · Standard Roadway & Utility Drawings
Concrete Bags vs Ready-Mix in Greensboro
For very small pours, bagged concrete can be practical. The calculator estimates approximate 60 lb and 80 lb bag counts using common planning yields. Manufacturer yield controls the real bag count, so always confirm the bag label.
For larger slabs and driveways, the number of bags can become substantial. A 5 cubic yard project represents 135 cubic feet. At 0.60 cubic foot per 80 lb bag, that would be about 225 bags before extra allowance. Ready-mixed concrete may be more practical for a continuous placement of that size.
Compare material cost, delivery access, crew size, mixing capacity and placement time. The cheapest nominal material option is not always the lowest installed-cost option.
Concrete Cost Calculator for Greensboro Projects
The optional price field multiplies adjusted cubic yards by your entered ready-mix price. This is a material-only estimate. It does not include delivery, pumping, short-load fees, reinforcement, forms, base preparation, demolition, labor, finishing, permits, inspections, curing materials or taxes.
Because concrete pricing changes by supplier, mixture, quantity, delivery conditions and time, this page does not hard-code a local per-yard price. Enter a current quote for the concrete mixture you actually expect to purchase.
How to Measure a Greensboro Concrete Project Accurately
Measure finished dimensions
Use the size of the concrete itself. Excavations can include working room, base material or other space that should not be filled.
Check depth at several locations
For slabs and driveways, base elevation can vary. Multiple depth checks give a better picture than one measurement.
Separate changing thicknesses
Calculate thickened edges, aprons, footings and pads as separate sections when their depth differs from the main slab.
Verify round-hole diameter
Pier holes can widen during drilling or excavation. Actual field diameter controls concrete consumption.
Recalculate before ordering
Preliminary dimensions are useful for budgeting. Final formed or excavated dimensions are better for the actual order.
Common Concrete Calculator Mistakes
Using square feet as concrete quantity
Square feet measure area, not volume. Thickness is required.
Entering inches as feet
A 4-inch slab is 0.3333 ft thick, not 4 ft.
Forgetting multiple sections
Repeated pads, piers and footing segments must be multiplied by quantity.
Double-counting thickened edges
If the base slab already includes part of a thickened section, add only the extra concrete below or beyond the base slab.
Ignoring center openings
Planter holes, large drains and annular openings should be subtracted when significant.
Treating calculator output as permit approval
Material quantity does not determine code compliance, drainage acceptance or inspection requirements.
Greensboro Concrete Project Checklist
Concrete Volume Examples for Greensboro
12 × 12 ft patio, 4 inches thick
12 × 12 × (4 ÷ 12) = 48 cubic feet, or approximately 1.78 cubic yards before allowance.
20 × 20 ft slab, 4 inches thick
20 × 20 × (4 ÷ 12) = 133.33 cubic feet, or approximately 4.94 cubic yards.
40 × 10 ft driveway section, 5 inches thick
40 × 10 × (5 ÷ 12) = 166.67 cubic feet, or approximately 6.17 cubic yards.
Four round piers, 18 inches diameter and 4 ft deep
Each pier is approximately 7.07 cubic feet. Four total approximately 28.27 cubic feet, or about 1.05 cubic yards.
Hot-Weather Concrete Planning in Greensboro
Hot and humid North Carolina weather can make concrete placement more demanding even when the material quantity is correct. High concrete temperature, sun, warm forms and wind can reduce the time available for placing, screeding and finishing.
Schedule ready-mix trucks for the crew's realistic production rate. If a pump is used, confirm pump location and hose reach before dispatch. If the placement relies on wheelbarrows or buggies, do not schedule trucks as though they can discharge directly into the forms.
Have the approved curing method and materials ready in advance. Quantity, delivery sequence and curing should all be planned before placement begins.
Rain, Thunderstorms and Concrete Placement in Greensboro
Heavy rain can soften subgrade, flood footing trenches, enlarge pier holes and leave low spots beneath slabs. If the prepared geometry changes after a storm, the concrete volume changes too.
Inspect excavations after significant rainfall and remeasure sections that will be placed directly against soil. A nominal pier or footing dimension is useful only when the field excavation still matches it.
For exterior slabs and driveways, make sure drainage paths are not blocked by temporary forms or material stockpiles, and have a practical protection plan for fresh concrete if showers are possible.
Subgrade and Base Preparation for Concrete Quantity Accuracy
Concrete volume depends on the space inside forms, so subgrade elevation directly affects quantity. If the base is one inch lower than planned across a large slab, the extra volume can be substantial. For example, one additional inch across 1,000 square feet equals about 83.33 cubic feet, or more than 3 cubic yards.
This is why good quantity estimating is tied to good preparation. Compact base material to the intended elevation, check grade in several locations and correct low spots before ordering. Do not rely only on perimeter form height if the interior base varies.
Uneven excavation
Footings and piers can be particularly sensitive to over-excavation. When concrete is placed directly against soil, enlarged trenches or holes become part of the concrete volume. If the design allows formed footings inside a larger excavation, measure the actual form dimensions instead.
Existing slabs and demolition
For replacement driveways or patios, measure after demolition when practical. Existing concrete thickness may not match the new design thickness, and removal can reveal base conditions that affect the final quantity.
Ready-Mix Delivery Planning in Greensboro
After the calculator gives an adjusted cubic-yard quantity, confirm how the concrete will reach the forms. Ready-mix trucks are large and heavy, and access can be limited by narrow residential streets, gates, overhead obstructions, soft shoulders, landscaping or distance from the truck to the placement area.
If the truck chute cannot reach the pour, the project may need wheelbarrows, a buggy, conveyor or concrete pump. Those methods can affect placement speed and labor requirements even though they do not change the geometric volume.
Truck count
Large pours may require multiple trucks. Use the Concrete Truck Count Calculator after determining total cubic yards. Delivery spacing should match the crew's actual placement rate.
Short loads
Small orders can be subject to supplier minimums or short-load charges. For a project close to the practical bag-versus-ready-mix threshold, compare the full delivered price rather than only the price per cubic yard.
Concrete Driveway Volume with Widened Aprons and Parking Pads
Many driveways are not perfect rectangles. A driveway may be 10 feet wide near the garage, widen to 16 feet at a parking area, and flare again near the street. The best estimating method is to divide the layout into simple sections.
Calculate the main rectangular run first. Calculate the parking pad as another rectangle. For a tapered apron, use an average width when the taper is approximately straight: add the narrow width and wide width, divide by two, then multiply by length and thickness. For highly curved geometry, use a more exact plan-area method.
Multiply the resulting area by slab thickness to obtain volume.
Keep each section in a worksheet so dimensions can be checked independently. This is easier to revise if a form line changes before the pour.
Concrete Patio Volume with Borders, Steps and Footings
A patio may contain more concrete than the flat slab alone. Thickened perimeter edges, steps, seat-wall footings, equipment pads or column footings can add substantial volume. Calculate the flat patio first, then add only the additional non-overlapping concrete for each feature.
For a step, calculate width × tread depth × riser height when the step is a solid rectangular block. Multi-step geometry may require several blocks. For round columns or posts supporting a patio cover, use the round-pier calculator mode.
If a decorative border uses a different mix, color or finish, keep its volume separate so the supplier quantity and cost can be estimated independently.
Greensboro Permit Research Before You Order Concrete
Permit research should happen before the final order whenever approved plans control concrete dimensions. Greensboro's Building Inspections Division provides plan review, permitting and inspections, while the City also maintains online permit, fee and inspection resources.
Plan review can change footing width, foundation depth, slab area, driveway geometry or other project details. If approved dimensions change, recalculate the material quantity before ordering.
Concrete can also conceal reinforcing steel, footing geometry, anchors and embedded work. Coordinate required inspections before placement so work that must remain visible is not covered too early.
Finished Elevation, Frost and Local Site Requirements in Greensboro
Foundation depth, frost-related details, base preparation and finished elevations are design and code questions, not quantity questions. Enter the dimensions required for the specific Greensboro project rather than choosing them from a generic online table.
Exterior concrete must also connect correctly with doors, garages, sidewalks, curbs and drainage grades. If the base is too low, simply filling the difference with extra concrete can change elevation, dead load and cost.
Use approved dimensions for structural work
For footings, structural slabs, walls and other load-bearing concrete, calculate volume from approved dimensions. If plan review or site conditions require a change, update the estimate before the concrete order is placed.
Concrete Reinforcement and Volume Are Separate Calculations
Reinforcing steel, welded wire reinforcement, fibers and dowels can be important to a concrete project, but they usually do not reduce concrete volume enough to deduct from an ordinary ready-mix order. Calculate the gross concrete shape and estimate reinforcement separately.
Use the Concrete Rebar Length Calculator for bar-length planning when bar size and spacing are already specified. The concrete calculator does not determine whether reinforcement is required or what spacing should be used.
Similarly, joints should be planned from the project requirements rather than inferred from cubic-yard quantity. A large volume does not automatically dictate one joint spacing.
Concrete Formwork and Quantity Coordination
Formwork controls concrete geometry. Bowed forms, loose stakes or incorrect elevations can increase volume and alter the finished shape. Before ordering, walk the forms and verify length, width, diagonals, curve radius and top elevation.
For walls and footings, measure inside form dimensions. For slab edges, check that forms are supported well enough to resist movement during placement. Flexible circular forms should be checked from a fixed center point.
Use the Concrete Form Area Calculator when you also need an estimate of sheathing or contact area. Form area and concrete volume are different measurements and should not be confused.
Estimating Concrete for Multiple Greensboro Projects
If one property includes a patio, walkway, equipment pad and several piers, calculate each project component separately. Add the exact cubic feet only after every section has been checked. Then apply an allowance to the combined order if the same concrete mixture will be placed together.
If different concrete mixtures are required, keep the quantities separate. A decorative patio mix should not be combined with structural footing concrete merely because both are being poured on the same property.
Label each calculation with dimensions and intended use. A clear takeoff makes it easier to compare the final order with revised plans or field measurements.
Concrete Calculator in Greensboro: Final Ordering Checklist
- Confirm the project address is under City of Greensboro or another local jurisdiction.
- Verify current building-permit and inspection requirements.
- Check whether driveway access to a City street needs a separate driveway permit.
- Use approved structural dimensions where plans are required.
- Recheck slab thickness, footing depth, wall thickness and pier dimensions after layout.
- Inspect excavation and subgrade after heavy rain or equipment traffic.
- Separate sections with different thicknesses, elevations or concrete mixtures.
- Keep exact geometric volume separate from ordering allowance.
- Confirm supplier minimums, short-load fees, truck capacity and site access.
- Coordinate pump, buggy or wheelbarrow access when truck chutes cannot reach the forms.
- Check the current Greensboro weather forecast close to placement time.
- Confirm required inspections before concrete conceals reinforcement or footing work.
Contractor and Inspection Planning in Greensboro
Greensboro's developer and contractor resources provide online access to plan review, building permits and building inspections. For projects performed by a contractor, confirm that the contractor is properly qualified for the work and that all required permits are associated with the correct project before concrete is scheduled.
For larger jobs, inspection timing can affect truck scheduling. If footing, reinforcing or embedded items must be inspected before placement, do not dispatch ready-mix until the required inspection is complete or the inspector has confirmed the work can proceed.
Permit approval, contractor qualification and concrete quantity are separate issues. A correct cubic-yard calculation does not replace any required license, permit or inspection.
Greensboro vs State Building-Code Review
North Carolina's State Building Code establishes the technical code framework, while Greensboro's Building Inspections Division performs local plan review, permitting and inspections for projects under City jurisdiction.
This distinction matters because a statewide code document may describe minimum technical requirements, while the City permit process determines what plans, applications, inspections and local approvals are needed for the specific Greensboro project.
Use the calculator only after you know the concrete geometry. For structural work, approved plans should control the dimensions entered into the calculator.
Greensboro Driveway, Sidewalk and Street-Connection Concrete
Driveway projects can include several distinct concrete areas: the private driveway slab, the driveway approach near the street, a sidewalk crossing, curb-and-gutter transitions and sometimes drainage features. Those pieces can have different dimensions and City requirements, so estimate them separately when possible.
Greensboro's roadway standard drawings include a typical walk and residential driveway section for curb-and-gutter streets, along with separate commercial driveway details and concrete curb-ramp standards. The City's permits page also lists a driveway permit for driveway access to City streets.
Use the approved drawing or permit dimensions for the public-side section. Do not assume the thickness and reinforcement used on a private driveway automatically apply to the approach or sidewalk area.
Related Concrete Calculators
Use the Concrete Pour Calculator for a general material order, the Concrete Cubic Foot Calculator for cubic-foot conversion, the Concrete Pier Calculator for detailed pier geometry, the Concrete Form Area Calculator for formwork contact area, the Concrete Density Calculator for project weight, and the Concrete Truck Count Calculator for delivery-load planning.
For broader concrete technical information, consult the American Concrete Institute and the American Cement Association.