Short answer: multiply the driveway's length by its width (in feet) to get square feet, multiply by the depth (in inches divided by 12) to get cubic feet, then divide by 27 to get cubic yards. Add a margin, then multiply by your material's density to get tons. A 50 × 12 ft driveway covered 4 in deep is about 7.4 cubic yards before any margin, and about 8.1 cubic yards with a 10 percent margin. At a typical density of 1.4 short tons per cubic yard that is roughly 11.4 short tons.

The part no formula can give you is the depth. Use the depth your project calls for, which depends on your soil, your traffic and any local requirements. Your supplier or contractor can tell you what applies where you live. The numbers in this guide use 4 in only as an example.

If you just want the answer for your own measurements, use the gravel calculator. Read on if you want to understand the result, check a quote, or spot why two numbers differ.

The formula, step by step

  1. Area in square feet. For a rectangle, length × width. For a driveway that is not a rectangle, split it into rectangles, circles and triangles, work out each one, and subtract any part that will not be covered.
  2. Depth in feet. Divide inches by 12. Three inches is 0.25 ft.
  3. Volume in cubic feet. Area × depth in feet.
  4. Volume in cubic yards. Cubic feet ÷ 27, because one cubic yard is 3 ft × 3 ft × 3 ft.
  5. Margin. Multiply by 1.10 to add 10 percent for compaction and waste.
  6. Weight in short tons. Cubic yards × density in short tons per cubic yard.

Worked example: a 50 × 12 ft driveway, 4 in deep

Step Calculation Result
Area 50 ft × 12 ft 600 ft²
Depth 4 in ÷ 12 0.333 ft
Volume 600 ft² × 0.333 ft 200 ft³
Cubic yards 200 ÷ 27 7.41 yd³
With 10% margin 7.41 × 1.10 8.15 yd³
Weight at 1.4 short tons/yd³ 8.15 × 1.4 11.41 short tons

With a 10-ton truck, 11.41 tons is two loads, so ask your supplier whether they can deliver a partial load or want you to order a different quantity. Our calculator reports truckloads if you enter a truck capacity.

Quick reference: gravel per 100 square feet

These values are plain arithmetic (area × depth ÷ 27) and use the same 10 percent margin as the calculator. Multiply by your area divided by 100.

Depth Cubic yards (no margin) Cubic yards (+10%) Short tons at 1.4 (+10%) Short tons at 1.7 (+10%)
2 in 0.62 0.68 0.95 1.15
3 in 0.93 1.02 1.43 1.73
4 in 1.23 1.36 1.90 2.31
6 in 1.85 2.04 2.85 3.46

Why tons are a range, not a single number

Cubic yards are geometry. Tons depend on what the stone weighs, and that varies with the type of rock, the size of the pieces, how much fine material is mixed in and how wet it is.

  • Billdr and Inch Calculator both publish a range of 1.4 to 1.7 short tons per cubic yard for crushed stone of roughly 1/4 in to 2 in. Our calculator starts at the low end, 1.4.
  • Select Sand & Gravel says a cubic yard of crushed stone that includes fines (crusher run, road base) can weigh up to about 3,000 lb, or 1.5 short tons. Our calculator uses 1.5 for crusher run and treats it as approximate.
  • The same Select Sand & Gravel guide puts clean crushed stone, without fines, at about 2,700 to 2,800 lb per cubic yard (1.35 to 1.4 short tons), so some products sit just below our 1.4 starting point.

These are typical values from calculators and a supplier's guide, not a standard, so the safest step is to ask your supplier for the weight of the product you are buying. The effect is large: the same 50 × 12 ft, 4 in driveway comes to 11.41 short tons at 1.4, 12.22 at 1.5 and 13.85 at 1.7. If you enter your supplier's number in the calculator's density field, it replaces the default.

How much extra to order

Loose stone settles when it is spread and compacted, and some is lost at the edges. The calculator adds 10 percent by default. That is an assumption, not a rule: a tight, well-measured area may need less, and an uneven base may need more. You can change the margin.

Common mistakes

  • Mixing units. Entering 4 as feet instead of 4 inches makes the answer twelve times too big. Convert depth to feet or let the calculator do it.
  • Using the wrong yard. Cubic yards are volume. Square yards are area. A quote in tons cannot be compared with a quote in cubic yards without the density.
  • Treating one density as fact. The difference between 1.4 and 1.7 short tons per cubic yard is more than 20 percent of the order.
  • Forgetting the margin. An order sized exactly to the formula is usually short once the stone is spread and compacted.
  • Rounding down to fit a truck. Round up, or agree with the supplier how a partial load is handled.
  • Measuring the shape wrong. For a curved or tapered driveway, split it into simple shapes instead of guessing an average width.

What this guide cannot tell you

  • The right depth. It depends on your use, soil and local requirements. Ask your supplier or contractor.
  • Preparation of the ground, drainage or edging.
  • The price. It varies by supplier and location, and we do not publish prices.

The calculator gives planning estimates, not engineering advice. If you are paving over the gravel later, see how to calculate asphalt tonnage for a driveway. Our assumptions are listed on the methodology page.

Frequently asked questions

Is a ton of gravel the same as a cubic yard?

No. A cubic yard is a volume (27 cubic feet) and a ton is a weight. Converting one to the other needs the density of your material, which is why the same job can be quoted in either unit.

Do I order short tons or metric tons?

Our US calculator uses short tons (2,000 lb). Suppliers quote in whichever unit their scale ticket uses, so confirm it before you compare quotes.

How many bags of gravel is that?

Divide the cubic feet you need (including the margin) by the volume printed on the bag and round up. For a 10 × 4 ft area at 2 in with 0.5 cubic foot bags, that is 15 bags.

Should I add extra to my gravel order?

A margin for compaction and waste is normal. Our calculator defaults to 10 percent, which is a planning assumption you can change, not a standard.

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