Gravel Calculator
Calculate how much gravel you need for your driveway, pathway, or landscaping project. Get results in cubic yards and tons.
How to Calculate Gravel
- Measure the area in feet (length × width). For irregular shapes, break into rectangles and add them up.
- Choose the depth: 4-6 inches for driveways, 2-3 inches for walkways, 1-2 inches for decorative beds.
- Calculate cubic yards: Length × Width × Depth (in inches) ÷ 324 = cubic yards.
- Convert to tons: Cubic yards × density factor (typically 1.4 for crushed stone).
- Add 10% extra for compaction and waste.
Gravel Depth Recommendations
- Driveways: 4-6 inches (base layer of larger stone + top layer of finer gravel)
- Walking paths: 2-3 inches
- Decorative beds: 1-2 inches
- French drain: 8-12 inches depth in the trench
How much gravel for a 20x20 driveway?
For a 20 ft by 20 ft driveway at 4 inches deep, the math is: 20 × 20 × 4 ÷ 324 = 4.94 cubic yards. With average crushed stone density, that is about 6.9 tons before any local delivery minimums.
If the base is soft, uneven, or needs a separate larger stone layer, plan the layers separately instead of treating the whole driveway as one material. A 10% buffer is useful for compaction and low spots, but it is not a substitute for fixing poor drainage or unstable soil.
Gravel calculator for French drain trenches
For a French drain, calculate the trench volume first, then adjust for pipe, fabric, and void space. A 50 ft trench that is 1 ft wide and 18 inches deep is 50 × 1 × 1.5 = 75 cubic feet, or 2.78 cubic yards before adjustments.
The actual gravel order may be lower if a large pipe occupies part of the trench, but many projects still keep a small buffer because trench sides are rarely perfect rectangles.