Slabs • Patios • Driveways • Footings • Posts
Use this Concrete Calculator in Colorado to estimate cubic feet, cubic yards, concrete bags and material cost for Colorado-area slabs, patios, driveways, sidewalks, footings, posts and other concrete projects. Enter your actual dimensions and local material price for a project-specific estimate.
Estimate slabs and patios, continuous footings, round posts/columns, or convert known square footage into bags and ready-mix cost.
Enter finished dimensions for a patio, driveway panel, garage slab, sidewalk section or other rectangular concrete flatwork.
Verify manufacturer bag yield.
Thickened edges, footings, steps and other deeper concrete sections should be calculated separately.
Estimate a uniform continuous footing, grade beam or strip foundation.
Estimate concrete for cylindrical posts, piers and round columns.
Already know the square footage? Convert area and slab thickness into cubic yards, bag quantity and material cost.
The calculator works from geometry, so the first step is measuring the actual concrete dimensions. For a slab, patio or driveway panel, measure finished length and width and enter the planned slab thickness. For a footing, measure total continuous length and use the actual width and depth from the project design. For posts or piers, use the finished diameter and poured height/depth.
After calculating exact volume, compare it with an optional allowance. The allowance is not a mandatory Colorado percentage—it simply gives you a larger planning quantity to compare against the mathematical volume.
Use finished concrete dimensions.
Slab, footing, round post or area.
Use the project-specific concrete thickness.
Enter an Colorado-area supplier quote if desired.
Check permits, plans and field dimensions.
For most rectangular slabs, the concrete quantity formula is straightforward.
Cubic yards = cubic feet ÷ 27.
A 20 × 20 foot slab at 4 inches thick contains about 133.33 cubic feet, or approximately 4.94 cubic yards before an ordering allowance.
| Project | Example Size | Thickness | Approx. Concrete |
|---|---|---|---|
| Small Patio | 10 × 12 ft | 4 in | 1.48 yd³ |
| Patio / Slab | 12 × 20 ft | 4 in | 2.96 yd³ |
| Garage Floor | 20 × 20 ft | 4 in | 4.94 yd³ |
| Driveway Section | 20 × 30 ft | 5 in | 9.26 yd³ |
| Large Slab | 30 × 40 ft | 6 in | 22.22 yd³ |
These are geometric examples only. Actual thickness, reinforcement, base preparation and project design can differ.
Location-focused guidance without forcing a single local price.
Calculations use project dimensions rather than broad averages.
Compare bagged concrete for smaller pours.
Estimate cubic yards before requesting a supplier quote.
Slabs are among the most common concrete projects in Central Colorado, including patios, garage floors, sheds, equipment pads and other flatwork. The slab calculator converts the surface footprint and thickness into concrete volume.
Do not use excavation depth as slab thickness. Excavation can also contain compacted base, drainage layers or other materials. Enter the actual concrete thickness shown on the project plan.
For a dedicated slab page, use the Concrete Slab Calculator. For floor-specific work, use the Concrete Floor Calculator.
For a rectangular patio, multiply length by width to get square footage, then multiply by slab thickness. Irregular patios can be divided into rectangles, circles or other simple shapes and calculated separately.
Use the Concrete Patio Calculator for circular and L-shaped patio geometry.
A driveway or sidewalk estimate should use the actual concrete footprint and specified thickness. If a driveway contains an approach, apron, thickened edge, separate pad or sloped transition, calculate those sections separately and add the cubic-yard totals.
Public sidewalk, curb, gutter and driveway-approach work can be regulated by the local city, county or road authority. Use this calculator for material quantity, then verify right-of-way, drainage, access and permit requirements for the project location.
Continuous strip footings and grade beams are calculated from total length × width × depth. The calculator does not size a footing structurally. Soil conditions, loads, building type and code requirements can affect foundation design, so use dimensions from approved plans or qualified design guidance.
For more detail, use the Concrete Footing Calculator or Concrete Foundation Wall Calculator.
Round concrete posts and piers use the cylinder formula π × radius² × height. If the project includes an enlarged footing at the bottom, calculate that footing separately. For larger structural columns, use the Concrete Column Calculator.
Concrete prices can change by supplier, mix specification, delivery distance, order size and additional service charges. Rather than hard-coding a citywide price, the calculator lets you enter a current local quote per cubic yard.
For sealer quantities after the project is ready for treatment, use the Concrete Sealer Coverage Calculator.
The same cubic-yard formulas apply in Denver, Colorado Springs, Aurora, Fort Collins, Lakewood, Thornton, Arvada, Westminster, Pueblo, Boulder and mountain towns. What changes are local code adoption, permit requirements, supplier pricing, delivery distance, elevation, weather and site access.
Use this page for quantity planning, then confirm mix specifications, delivery timing, permit requirements and construction details with the local building authority, project professionals and ready-mix supplier.
Colorado concrete permit requirements can vary significantly by city and county. The Colorado Corporation Commission explains that Colorado is a home-rule state for building energy codes, with adoption and enforcement handled by local jurisdictions. That local-control pattern is important when planning concrete work because the applicable permit process, inspections, frost-depth requirements, driveway approach rules and adopted code edition can differ from one community to another.
The Colorado State Fire Marshal also works with local fire and building officials through plan review and inspection coordination. For an actual slab, driveway, footing, foundation or structural concrete project, verify the current requirements with the local authority having jurisdiction rather than assuming one statewide permit rule.
Official resources: Colorado Corporation Commission — Building Energy Codes and Colorado State Fire Marshal — Plans Review & Code Footprint.
Colorado building permits and development review are primarily handled at the local level for ordinary private projects. The Colorado Department of Local Affairs notes that local governments commonly maintain separate development-review and building-permit processes, which means the exact permit path depends on the city or county responsible for the property.
Before constructing a structural slab, foundation, retaining wall, driveway approach or other regulated concrete work, check the local building department and public-works or engineering department. State-owned facilities follow separate State Buildings Program requirements.
Official resource: Colorado Department of Local Affairs — Development Review FAQ.
Cold-weather concreting is especially important in Colorado because freezing conditions and large temperature swings can occur across much of the state. The volume formula does not change, but fresh concrete may need temperature control, protection and curing procedures appropriate to the project conditions.
Use ACI PRC-306-16: Guide to Cold Weather Concreting for technical cold-weather guidance. ACI explains that cold-weather procedures are intended to help concrete develop the intended strength and durability while avoiding damage from early freezing.
Colorado can also produce hot, dry and windy placement conditions, especially during summer and at exposed sites. These conditions can increase evaporation and reduce the time available for finishing. The concrete quantity remains a geometry problem, but placement and curing planning may need to change.
For hot-weather work, review ACI PRC-305-20: Guide to Hot Weather Concreting. Coordinate actual mix, delivery and curing decisions with the project specification and ready-mix supplier.
Mountain and high-elevation projects can involve longer truck travel, steep access, colder nights, rapid weather changes and limited placement windows. Elevation itself does not change cubic-yard volume, but logistics and seasonal conditions can affect how a pour is scheduled and protected.
Measure actual formed dimensions, confirm site access before ordering and discuss delivery timing with the supplier. For remote or difficult placements, compare the final quantity with the Concrete Truck Count Calculator and Concrete Pump Capacity Calculator.
Use the Slab / Patio mode for garage floors, driveways, patios and walkways. Use the Footing / Grade Beam mode for continuous foundation elements, and the Round Post / Column mode for cylindrical posts or piers. When a project contains different shapes, calculate each one separately and combine the cubic-yard totals.
For foundation walls, use the Concrete Foundation Wall Calculator. For column work, use the Concrete Column Calculator.
For cold-season work, use ACI PRC-306-16. For hot, dry or windy placement, use ACI PRC-305-20. These resources address concrete production, placement, finishing, protection and curing under demanding weather conditions.
Roadway, bridge, pavement, curb and other public-infrastructure concrete should follow approved plans and agency specifications rather than residential calculator assumptions.
The Colorado Department of Transportation publishes the 2025 Standard Specifications for Road and Bridge Construction. CDOT states that the 2025 edition supersedes the 2023 edition for its contract work.
The same cubic-yard formulas apply in Denver, Colorado Springs, Aurora, Fort Collins, Lakewood, Thornton, Arvada, Westminster, Pueblo, Boulder and mountain communities. What changes are local permitting, adopted codes, delivery distance, elevation, weather and site access.
Use this page for quantity planning, then confirm mix specifications, delivery scheduling, permit requirements and construction details with the local authority, project professionals and ready-mix supplier.
Ready-mix prices can vary with mix specification, order size, travel distance, mountain delivery, short-load fees, waiting time and pumping requirements. For that reason, the cost field in this calculator is editable instead of using one fixed statewide price.
Enter the current price per cubic yard from the supplier you plan to use. The calculator estimates concrete material only and does not include excavation, forms, reinforcement, labor, pumping, permits, testing, finishing or curing.
The mathematical result is accurate when the entered dimensions match the actual formed or excavated geometry. The largest field-estimating errors usually come from incorrect thickness, irregular shapes, uneven excavation, omitted thickened edges or measurement mistakes.
Re-measure installed forms before ordering, calculate irregular sections separately and confirm supplier minimum-load and delivery policies. A practical allowance can help cover normal field variation, but accurate measurement should come first.
Concrete quantity comes from finished project dimensions. Weather affects placement and curing procedures, not the basic geometric volume.
Suppose a Colorado residential slab is 12 feet by 20 feet and 4 inches thick. The area is 240 square feet, and the thickness is one-third of a foot.
With a 10% planning allowance, the calculator shows about 3.26 cubic yards.
Common questions about Colorado concrete yards, slabs, patios, driveways, bags, cost and permits.