How to Calculate Exactly How Much Gravel Your Project Needs
By the Super Simple Digital Tools Team · Updated June 2026
Ordering gravel by eye is a common and expensive mistake. Stone is heavy, sold by minimum loads, and a pain to return, so the difference between a confident estimate and a guess is real money. The good news is that the underlying calculation is simple arithmetic, and once you understand it you can sanity-check any quote a supplier gives you. This guide walks through the method the calculator uses so you can measure once, order once, and finish the job in a single delivery.
Start with three measurements taken in consistent units: the length and width of your area in feet, and the depth of gravel you want in inches. Length times width gives your area in square feet. Multiply that by your depth converted to feet (inches divided by 12) and you have cubic feet. Divide cubic feet by 27 to get cubic yards, the unit most yards price by. A 30 by 12 foot driveway laid 5 inches deep, for instance, is 360 square feet times 0.417 feet, about 150 cubic feet, or roughly 5.5 cubic yards.
To turn volume into weight, multiply cubic yards by the density of your gravel. A safe working figure is 1.4 to 1.7 tons per cubic yard; lighter rounded pea gravel sits near the bottom of that range and dense crushed stone near the top. Our 5.5 cubic yard driveway therefore lands around 8 to 9 tons. Knowing both numbers matters because some suppliers quote in yards and others in tons, and having both lets you compare prices without redoing the math at the counter.
Depth is the variable people get wrong most often, because it scales the whole job. Decorative borders and walking paths are fine at 2 to 3 inches, but a driveway that takes vehicle weight needs 4 to 6 inches and usually a separate compacted base layer of angular crushed stone underneath. If your project has layers, calculate each one separately with its own depth and add the results. Skimping on depth saves material today but leads to ruts, bare patches, and a top-up order next season.
Finally, always add an overage. Gravel settles and compacts by 20 to 30 percent once it is walked on or driven over, and a little is always lost in handling and spreading into edges. Padding your final figure by 10 to 20 percent absorbs this without leaving a wasteful surplus. Break any oddly shaped area into rectangles before you measure, double-check your depth against the use case, and you will have a number you can hand to a supplier with confidence.
- Measure depth in inches and let the calculator convert it; entering 6 inches as 6 feet is the single most common error and inflates your order twelvefold.
- For driveways, calculate the crushed-stone base layer and the surface layer as two separate jobs, since they have different depths and densities.
- Get the exact tons-per-cubic-yard density from your supplier before a large order; the rock type can swing your weight estimate by several tons.
- Add roughly 15 percent overage on small jobs and 10 percent on loads over 5 tons to cover compaction and spreading loss without overbuying.