Estimate Gravel for Concrete Mixes
Use this Gravel Calculator for Concrete to estimate coarse aggregate for slabs, patios, footings, pads and other concrete projects. Calculate gravel volume, pounds and tons from cubic yards, project dimensions or a custom cement:sand:gravel mix ratio.
Estimate aggregate from concrete volume, reverse gravel into concrete yield, calculate from project dimensions, or build a custom mix-ratio estimate.
Enter finished concrete volume and choose a nominal mix ratio to estimate coarse aggregate.
Enter the wet/finished concrete volume.
Common estimating factor for loose dry ingredients.
Estimate how much finished concrete a known gravel quantity could support under a selected nominal mix.
Calculate finished concrete volume from slab or pad dimensions, then estimate the gravel portion.
Use your own cement:sand:gravel proportion for a more flexible estimating calculation.
A concrete mix contains cementitious material, fine aggregate such as sand, coarse aggregate such as gravel or crushed stone, and water. This Gravel Calculator for Concrete focuses on the coarse-aggregate portion. Because the exact aggregate content of structural and ready-mixed concrete depends on strength requirements, aggregate grading, moisture, air content, admixtures and the approved mix design, there is no single universal gravel amount that fits every cubic yard of concrete.
For planning small site-mixed jobs, a nominal ratio can still be useful. A ratio written as 1:2:3 means one part cement, two parts sand and three parts gravel by volume. The calculator first converts finished concrete into cubic feet, applies a dry-volume factor, then assigns the gravel share according to the selected ratio.
For a 1:2:3 mix, gravel is 3 of 6 total dry-volume parts.
Divide pounds by 2,000 to convert the estimate to US short tons.
The table below shows rough planning quantities using a 1.54 dry-volume factor and 100 lb/ft³ gravel bulk density. It illustrates how strongly the selected ratio changes the coarse-aggregate estimate.
| Nominal Mix | Gravel Share | Gravel ft³ / yd³ Concrete | Gravel yd³ | Approx. Weight |
|---|---|---|---|---|
| 1:1.5:3 | 3 / 5.5 | 22.68 ft³ | 0.84 yd³ | 2,268 lb / 1.13 tons |
| 1:2:3 | 3 / 6 | 20.79 ft³ | 0.77 yd³ | 2,079 lb / 1.04 tons |
| 1:2:4 | 4 / 7 | 23.76 ft³ | 0.88 yd³ | 2,376 lb / 1.19 tons |
| 1:3:6 | 6 / 10 | 24.95 ft³ | 0.92 yd³ | 2,495 lb / 1.25 tons |
These are loose dry-ingredient estimates. Actual batch weights can differ because aggregate density and moisture vary, and professionally proportioned mixes are normally designed by weight rather than by a simple bucket ratio.
Bulk density is especially important when converting gravel volume into pounds or tons. Rounded gravel, crushed stone, grading, moisture and compaction can all change the mass that fits into a cubic foot. If your supplier provides a specific loose bulk density or weight per cubic yard, enter that value rather than relying on the default.
Using the default assumptions on this page—1:2:3 by volume, a 1.54 dry factor and 100 lb/ft³ gravel bulk density—one finished cubic yard of concrete requires an estimated 20.79 cubic feet of loose gravel. That is about 0.77 cubic yard of gravel by loose volume and approximately 2,079 pounds, or 1.04 tons.
This does not mean that 0.77 cubic yard of gravel plus the other dry ingredients will simply occupy one cubic yard when placed side by side. Smaller particles fill voids between larger aggregate particles, cement paste surrounds the aggregate, and the concrete consolidates. That is why the dry loose volume of ingredients can exceed the final placed concrete volume.
At 1:2:3, estimated gravel is about 10.40 ft³ before extra allowance.
At 1:2:3, estimated gravel is about 20.79 ft³ or 1.04 tons at 100 lb/ft³.
At 1:2:3, estimated gravel is about 41.58 ft³ or 2.08 tons before allowance.
At 1:2:3, estimated gravel is about 62.37 ft³ or 3.12 tons before allowance.
Change cement, sand and gravel parts in the Custom Mix panel to model another nominal recipe.
When you know slab dimensions rather than cubic yards, first calculate the wet concrete volume. Multiply length by width by thickness, making sure thickness is converted from inches to feet. Divide cubic feet by 27 to get cubic yards. The Project → Gravel calculator does these steps automatically and then applies the selected gravel ratio.
Example: a 12 ft × 10 ft slab at 4 in thick is 40 ft³, or about 1.4815 yd³.
With the default 1:2:3 mix assumptions, that 12 × 10 × 4-inch slab corresponds to roughly 30.8 ft³ of loose gravel before any extra allowance. The calculator also converts the aggregate quantity into estimated pounds and tons.
A modest planning allowance can help when field dimensions are imperfect or material is spilled, left in the mixer, contaminated or lost during handling. The calculator defaults to a 5% allowance in the main and project calculations, but this is editable. Do not automatically increase aggregate alone when following a specified concrete mix: the proportions of cement, sand, aggregate and water should remain consistent. An allowance means scaling the whole planned batch volume, not randomly adding more gravel to the same cement content.
The term “gravel” is often used casually for coarse concrete aggregate, but actual coarse aggregate may be natural rounded gravel, crushed stone or a blend meeting grading requirements. Particle shape influences workability, paste demand and interlock. Rounded gravel can move more easily in a mix, while angular crushed stone can provide stronger mechanical interlock but may require different paste or admixture adjustments for the same workability.
For estimating quantity, this calculator treats both as a coarse aggregate with an editable bulk density. For structural performance, durability and workability, use aggregate that meets the project specification and applicable standards rather than choosing material only by estimated tonnage.
Volume and weight are not interchangeable unless density is known. Two gravel products can both occupy one cubic yard but weigh differently because of stone type, particle size distribution, moisture and void space. The default 100 lb/ft³ value is deliberately editable. If a supplier quotes, for example, 2,700 lb per loose cubic yard, divide by 27 to get 100 lb/ft³ and enter that density. If the supplier gives a different number, use the supplier value.
| Bulk Density | Weight per ft³ | Weight per yd³ | Use |
|---|---|---|---|
| 90 lb/ft³ | 90 lb | 2,430 lb | Lighter loose aggregate estimate |
| 100 lb/ft³ | 100 lb | 2,700 lb | Default planning value |
| 105 lb/ft³ | 105 lb | 2,835 lb | Denser aggregate estimate |
| 110 lb/ft³ | 110 lb | 2,970 lb | Heavier loose aggregate estimate |
Simple ratios are convenient for educational calculations and small noncritical site work, but modern concrete is usually proportioned to meet specific performance requirements. A ready-mix producer may adjust coarse aggregate, fine aggregate, cementitious material, water reducer, air entrainment and supplementary cementitious materials to reach a target slump, strength, durability and pumpability.
That means a “4,000 psi concrete” mix should not be recreated simply by picking a common cement:sand:gravel volume ratio from the internet. Strength depends strongly on water-cementitious ratio, curing, aggregate properties and quality control. Use this gravel calculator as a material-planning tool when a nominal ratio is appropriate, not as a substitute for professional mix proportioning.
A 1:2:3 mix divides the dry ingredient volume into one cement part, two sand parts and three gravel parts.
After calculating estimated tons, compare the result with the way your local supplier sells aggregate. Some suppliers sell by ton, others by cubic yard, and bagged aggregate may be sold by weight. Confirm whether the quoted yard is a loose-volume yard and ask whether delivery minimums apply. If your estimate is close to a supplier's load increment, it can be practical to round upward rather than risk stopping a concrete batch because aggregate runs out.
Keep the aggregate clean and separated from soil, leaves and standing water. Moisture in stockpiled aggregate also affects batching because wet sand and gravel contribute water to the mix. For controlled concrete, moisture corrections should be incorporated into the batch design rather than ignored.
Loose ingredients occupy more volume before mixing and consolidation, which is why the estimating method includes a dry-volume factor.
A 1:2:3 mix and 1:2:4 mix allocate different shares to coarse aggregate.
Use local supplier bulk density when available.
Scale the entire concrete batch allowance while keeping proportions consistent.
Specified concrete should follow the approved mix design and project documents.
Continue planning with our Concrete Calculator, Cement Sand Gravel Calculator, Concrete Batch Calculator, Concrete Bags to Cubic Yards Calculator, Concrete Slab Calculator and Concrete Yield Calculator. These internal tools help move from project dimensions to concrete volume, ingredients and bag quantities without mixing incompatible units.
For technical concrete information, consult the Portland Cement Association, the National Ready Mixed Concrete Association, and applicable ASTM International standards. Project specifications, local building requirements and producer mix designs should control where they differ from a general-purpose calculator.
Quick answers about gravel, coarse aggregate, concrete ratios, weights and project estimates.