How Much Gravel Do I Need? A Driveway Guide

Buying too little gravel means a second delivery fee and an uneven surface; buying too much leaves a pile you have to spread or haul away. The good news: the math is simple once you know your area and how deep you want the gravel. This guide walks through it, and the Gravel Calculator does the arithmetic for you.

The one formula behind every gravel estimate

Gravel is a volume problem. You need the length, width, and depth of the area you’re filling:

Cubic yards = (length ft × width ft × depth ft) ÷ 27

The only trick is that depth is usually in inches, so convert it to feet first by dividing by 12. A 4-inch layer is 4 ÷ 12 = 0.333 feet.

Then, because suppliers sell gravel by weight, convert cubic yards to tons by multiplying by the gravel’s density — about 1.4 tons per cubic yard for most gravel and crushed stone.

Worked example: a gravel driveway

Say you’re topping a 40-foot-long, 20-foot-wide driveway with 4 inches of gravel:

• Depth in feet: 4 ÷ 12 = 0.333 ft
• Cubic yards: (40 × 20 × 0.333) ÷ 27 = 9.88 yd³
• Tons: 9.88 × 1.4 = 13.8 tons

Round up when you order — you always lose a little to compaction and spreading. The Gravel Driveway Calculator is preset for driveway depths so you can skip the conversion.

How deep should the gravel be?

Depth matters more than most people expect, because it multiplies straight through the volume. Here’s the quick reference:

Use	Recommended depth
Decorative bed / path	2 in
Walkway	2–3 in
Driveway surface layer	4 in
Single-layer driveway	6 in
Base under pavers	4–6 in
French drain around pipe	3–4 in

For a driveway that will last, the pros build two layers: a coarse, angular base like crusher run that locks together, then a finer surface gravel on top. Calculate each layer separately — the base and the top are different depths and sometimes different materials.

Coverage: how far does a ton go?

If you’d rather think in coverage than volume, at a given depth one ton of gravel spreads over a predictable area:

Depth	Coverage per ton
2 in	~116 sq ft
4 in	~58 sq ft
6 in	~39 sq ft

So a 4-inch driveway at 800 square feet needs about 800 ÷ 58 ≈ 14 tons — the same answer as the volume method, just approached from the other direction.

Which gravel should you use?

“Gravel” covers a family of materials with slightly different densities and jobs:

• Crushed stone (like #57) — angular, drains well, good for driveways and drainage. Use the Crushed Stone Calculator.
• Crusher run — crushed stone with fines that compacts into a firm base; heavier at about 1.5 tons per yard.
• Pea gravel — small, round, decorative; comfortable underfoot but shifts, so it needs edging.
• River rock — larger decorative stone, priced higher and sold by the ton.

They all use the same volume formula; only the density changes, and every gravel calculator on this site already has the right density built in.

Common mistakes to avoid

1. Forgetting to convert depth to feet. Entering “4” instead of “0.333” overstates your order twelvefold.
2. Measuring only the surface layer. If you’re building a base plus a surface, that’s two calculations.
3. Not adding for compaction. Loose gravel settles 10–20% once driven on. Order a little extra.
4. Ignoring the base under a driveway. Gravel over soft soil sinks. A compacted sub-base is what makes it last.

Once you have your dimensions, drop them into the Gravel Calculator for an instant cubic-yard and ton figure, then confirm the final quantity with your supplier before ordering.