Gravel Driveway Calculator

How to Calculate Gravel for a Driveway

This guide shows how to calculate gravel for a driveway by hand, step by step, in US and metric units. The formulas and worked examples are the same ones the calculators on this site use, and the examples are checked against their code by automated tests.

Written by Mubarak Hussain · Examples checked by the site’s automated tests · Report an error

The formula in US units

  1. Area (ft²) = length (ft) × width (ft)
  2. Depth (ft) = depth (in) ÷ 12
  3. Volume (ft³) = area × depth (ft)
  4. Volume (yd³) = volume (ft³) ÷ 27
  5. Volume with allowance = volume (yd³) × (1 + allowance % ÷ 100)
  6. Weight (tons) = volume with allowance × density (tons per yd³)
  7. Order = weight rounded up to a whole ton

Worked example: a 60 × 12 ft driveway, 4 inches deep

area = 60 × 12 = 720 ft²
depth = 4 ÷ 12 = 0.3333 ft
volume = 720 × 0.3333 = 240 ft³
cubic yards = 240 ÷ 27 = 8.89 yd³
with a 10% allowance = 8.89 × 1.10 = 9.78 yd³
weight = 9.78 × 1.40 = 13.69 tons
order = 14 tons

The calculator keeps full precision between steps and only rounds what it displays, so rounding at each step by hand can occasionally move the last digit.

The formula in metric units

  1. Area (m²) = length (m) × width (m)
  2. Depth (m) = depth (cm) ÷ 100, or depth (mm) ÷ 1,000
  3. Volume (m³) = area × depth (m)
  4. Volume with allowance = volume × (1 + allowance % ÷ 100)
  5. Weight (tonnes) = volume with allowance × density (tonnes per m³)
  6. Order = weight rounded up to a whole tonne

Worked example: an 18 × 3.6 m driveway, 10 cm deep

area = 18 × 3.6 = 64.8 m²
depth = 10 ÷ 100 = 0.10 m
volume = 64.8 × 0.10 = 6.48 m³
with a 10% allowance = 6.48 × 1.10 = 7.128 m³
weight = 7.128 × 1.6612 = 11.84 tonnes
order = 12 tonnes

The density 1.6612 tonnes per m³ is the same 1.40 tons per cubic yard planning value converted exactly (1 ton per cubic yard = 1.186553 tonnes per cubic metre). Rounding it to 1.66 changes the result by less than 0.1%.

Adding the cost

material cost = exact weight (or volume) × your price per ton (or per yd³)
total = material cost + delivery

The calculators use the exact quantity, not the rounded-up order, and say so in the results. If your supplier charges for the full rounded amount, multiply the order by the price instead. For the US example at a price of P per ton, the material cost is 13.69 × P.

Why the allowance matters

The formula gives the volume of a perfect box, but a real driveway isn’t one. Loose gravel settles and its stones lock together when it is rolled or driven on, some stone is pressed into soft ground, and some is lost at the edges. Without an allowance, an order for the exact volume usually comes up short. The calculators default to 10% (15% for a base layer). That is a planning choice rather than a measured rate, so use your supplier’s or contractor’s figure if they give one.