Gravel Calculator
This gravel calculator works out the volume, weight, and approximate cost of the gravel you’ll need for a driveway, walkway, or bed. Enter your area and depth and get cubic yards, tons, and an estimated total in one step — no manual unit conversion required.
Also known as: gravel calc, gravel estimator, crushed stone calculator, gravel yardage calculator, gravel tonnage calculator.
For a quick gravel calc: multiply area (sq ft) by depth (in feet — divide inches by 12), then divide by 27 to get cubic yards. For a 10×10 ft driveway patch at 3 inches deep, that’s 100 × 0.25 ÷ 27 ≈ 0.93 cubic yards, or roughly 1.3 tons of standard gravel.
Area × (Depth ÷ 12) ÷ 27 = cubic yardsWhy Use a Gravel Calculator Before You Order
Gravel is delivered and quoted in two separate units: tons for weight and cubic yards for volume. Because most vendors charge by the ton while most people picture their project in square feet, a gravel calc has to bridge that gap in a single step — converting a length-and-width (or diameter) footprint plus a target depth into cubic feet, then cubic yards, then applying a material density to arrive at the tonnage a supplier will actually invoice.
Skipping this step is the most common way people either run short mid-project or overorder and pay for material they never spread. Since depth is entered in inches while area is in feet, a manual estimate is prone to a unit-conversion error — dividing by 12 for depth and then by 27 for cubic yards is exactly the kind of math a calculator handles more reliably than doing it by hand on a delivery-day deadline.
Different materials also carry meaningfully different weights for the same volume, since river rock, crushed stone, and pea gravel each settle into slightly different density ranges. For this reason, this calculator lets you select a common material preset or enter a specific figure rather than assuming one number works for every load.
How This Gravel Calculator Works
Gravel is supplied by volume (cubic yards) or weight (tons), but you can determine how much you need with a straightforward area-and-depth calculation.
The formula
Volume = Area × (Depth ÷ 12) ÷ 27. Multiplying area in square feet by depth in feet gives cubic feet, and dividing that result by 27 gives cubic yards.
Rectangular vs circular
Rectangular area is length × width. Circular area is π × (Diameter ÷ 2)² — useful for round fire pits, tree rings, or planters.
Typical material densities
| Material | lbs / cy |
|---|---|
| Pea gravel | 2,800 |
| Crushed stone | 2,700 |
| River rock | 2,650 |
| Sand | 2,600 |
What this doesn’t include
Because compaction allowance, transportation expenses, and sales tax vary by supplier, most vendors recommend buying roughly 10% extra to cover them.
Gravel Needed Per 100 Square Feet, By Depth
If you already know your area, this table gets you a rough cubic-yard figure without opening the calculator — based on a mid-range gravel density of 2,700 lbs per cubic yard.
| Depth | Cubic yards / 100 sq ft | Tons / 100 sq ft | Typical use |
|---|---|---|---|
| 2 in | 0.62 | 0.84 | Walking paths |
| 3 in | 0.93 | 1.25 | Driveways |
| 4 in | 1.23 | 1.67 | Base beneath pavers or a shed |
| 6 in | 1.85 | 2.50 | Heavy-duty driveway base |
Gravel Calculator: Two Real Walkthroughs
20×10 ft driveway, 3 inches deep
A homeowner is resurfacing a 20 ft by 10 ft gravel driveway and wants a 3-inch layer of crushed stone.
Given inputs
- Area: 20 ft × 10 ft = 200 sq ft
- Depth: 3 in
- Density: 2,700 lbs/cy (crushed stone)
Computed outputs
- Volume: 200 × 0.25 ÷ 27 ≈ 1.85 cubic yards
- Weight: 1.85 × 2,700 ÷ 2,000 ≈ 2.5 tons
12 ft diameter fire pit bed, 4 inches deep
A backyard fire pit area is 12 feet across, and the plan is to spread 4 inches of pea gravel around it.
Given inputs
- Diameter: 12 ft
- Depth: 4 in
- Density: 2,800 lbs/cy (pea gravel)
Computed outputs
- Area: π × 6² ≈ 113.1 sq ft
- Volume: 113.1 × 0.33 ÷ 27 ≈ 1.4 cubic yards
- Weight: 1.4 × 2,800 ÷ 2,000 ≈ 1.96 tons
Calculator Mistakes to Avoid
Entering depth in feet instead of inches
This gravel calculator internally converts depth from inches, so typing “3” as three feet rather than three inches will overstate the volume required by a factor of twelve.
Not accounting for compaction
Loose gravel settles after being driven or stepped on. As a result, the final coating often ends up thinner than expected when the exact predicted volume is ordered without extra — most vendors suggest buying about 10% more.
Using a generic density for every material
River rock, crushed stone, and pea gravel each weigh a different amount per cubic yard. Because of that, using one density figure for a different material can distort both the tonnage and the resulting cost estimate.
Forgetting delivery minimums and fees
This cost estimate simply multiplies tons by the price per ton. However, most vendors also impose minimum purchase sizes or delivery fees, so treat this as a starting point until you have a firm quote.
Gravel Calculator FAQ
How much gravel do I need?
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How deep should my gravel layer be?
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Should I order extra gravel beyond the calculated amount?
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Why does the calculator ask for a density?
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Do I need to know the exact density of my gravel?
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Is the cost estimate accurate?
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About This Calculator
I’m Umer Farooq, the founder of calcsdone and the person who built and maintains this gravel calculator. I check the volume and density math on this page against the USGS and FHWA references linked below, and I update it whenever a reference figure changes. If something looks off, get in touch or find me on LinkedIn.
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Gravel Calculator: Reference Data
- Construction Sand and Gravel Statistics and Information. U.S. Geological Survey, National Minerals Information Center.
- Crushed Stone Statistics and Information. U.S. Geological Survey, National Minerals Information Center.
- Sand and Gravel (Construction). Mineral Commodity Summaries 2026. U.S. Geological Survey.
- Granular Base — User Guidelines for Waste and Byproduct Materials in Pavement Construction. Federal Highway Administration.