Estimating Gravel for a Driveway: Depth, Coverage, and Tonnage

A gravel driveway is one of the most budget-friendly ways to get a hard standing surface, but the single most common mistake is under-ordering. Gravel arrives by the tonne, and running out three-quarters of the way through means a second delivery, a second delivery charge, and a visible seam where the two loads meet. Getting the volume right before you call the supplier is the whole game.

Start With Area, Not Length

The number you need is not “how long is my drive” but “how many square feet am I covering.” Measure the length and the width in feet and multiply. A drive that is 40 feet long and 12 feet wide covers 480 square feet. That figure — not the length — drives everything that follows.

If your drive is irregular, split it into rectangles, calculate each, and add them together. Round up rather than down; a little spare gravel is far cheaper than a second delivery.

Choose Your Depth

Depth is where most estimates go wrong, because a driveway is not a single layer. For a fresh surface over bare ground you generally want a compacted depth of about 4 inches of base material, with a top layer of finer gravel around 2 inches. Over an existing firm base, a 2 to 3 inch top-up is usually enough.

Deeper is not automatically better. Gravel that is too deep shifts underfoot like dry sand, and loose stone migrates to the edges. Match the depth to the job rather than piling it on.

Coverage by Depth — A Quick Reference

Compacted depth	Coverage per cubic yard	Typical use
2 inches	~160 sq ft	Top-up over firm base
3 inches	~108 sq ft	Light refresh, footpaths
4 inches	~80 sq ft	New drive base layer
6 inches	~54 sq ft	Soft or unstable ground

From Volume to Tonnage

Suppliers sell by weight, so you need to convert. A cubic yard of typical driveway gravel weighs roughly 1.4 tonnes, though this varies with stone type and moisture. Using the 480 square foot example at 4 inches deep, you need about 6 cubic yards, which lands around 8.4 tonnes.

Always add a waste factor. Five to ten percent covers spillage, compaction settlement, and uneven ground. Round your order up to the nearest half-tonne and you will rarely be short.

Choose the Right Stone Type

Crushed stone: locks together well, best as a base layer.
Pea gravel: smooth and easy underfoot, but migrates — better as a top dressing.
Recycled concrete: cheap and firm, good for long rural drives.
Quartz or granite chips: attractive top layer, higher cost.

Frequently Asked Questions

How deep should a gravel driveway be? A new drive usually needs about 4 inches of compacted base plus a 2 inch top layer.

How many tonnes do I need per square foot? At 4 inches deep, roughly 0.0175 tonnes per square foot including a small waste allowance.

Can I put gravel over soil? Only with a weed membrane and a compacted sub-base, otherwise the stone sinks and disappears.

Does gravel depth affect drainage? Yes. A proper base keeps water moving rather than pooling, which is why under-ordering depth causes long-term problems.

Do the Volume Maths First

Every gravel estimate reduces to three numbers: area, depth, and density. Get the area from a simple length by width measurement, use our area calculator to square it away, then apply the depth and the roughly 1.4 tonnes per cubic yard density. Order with a waste allowance and your driveway will finish in one delivery instead of three — saving both money and the frustration of a half-finished surface.