How do I calculate cubic feet of dirt?

Multiply length × width × depth in feet. A 20 × 10 × 2 ft excavation removes 400 ft³ of in-place dirt — once disturbed and loaded, that volume swells about 25%.

When you dig dirt, it expands ("swells") as it loses density. Excavated dirt typically swells 20–30% above its in-place volume. So 100 ft³ of in-place dirt becomes 120–130 ft³ of loose dirt to haul away.

How much does 1 cubic foot of fill dirt weigh?

Loose fill dirt weighs about 75–80 lb/ft³; compacted in-place dirt weighs about 100 lb/ft³. Wet clay can exceed 130 lb/ft³.

What is the difference between fill dirt and topsoil?

Fill dirt is mostly subsoil — clay, sand, and small rocks — used for grading and structural fill. Topsoil contains organic matter and supports plant life. Fill dirt is much cheaper and not suitable for gardens.

How much dirt do I need to raise my yard 6 inches over 500 ft²?

500 × 0.5 = 250 ft³ = 9.26 yd³. Order 10 yd³ to allow for compaction.

Dirt Calculator (Cubic Feet) — Tons, Yards & Dump Truck Loads for Fill

How to calculate cubic feet for dirt

Excavating, grading, and filling all start with a cubic-foot calculation. Multiply the length, width, and depth of the volume in feet. Include a swell factor when hauling — disturbed dirt occupies 20–30% more space than the same dirt in place.

For fills, also factor in compaction. Loose-delivered dirt drops 10–15% under a plate compactor.

Worked examples

Example 1: A 20 × 10 ft basement extension at 8 ft deep

20 × 10 × 8 = 1,600 ft³ in place. With 25% swell, you'll haul away ~2,000 ft³ of loose dirt = 74 yd³.

Example 2: Raising a 500 ft² lawn 6 inches

500 × 0.5 = 250 ft³ after compaction. Order ~290 ft³ (10.7 yd³) loose to compact down.

Example 3: A 30 ft trench, 2 ft wide × 3 ft deep

30 × 2 × 3 = 180 ft³ in place; ~225 ft³ loose to haul away.

Soil swell factors by type

Material	Conversion factor	Worked example
Topsoil / loam	20%	100 ft³ → 120 ft³ loose
Sand	12%	100 ft³ → 112 ft³ loose
Clay	40%	100 ft³ → 140 ft³ loose
Gravel	12%	100 ft³ → 112 ft³ loose
Rock (fragmented)	50–80%	100 ft³ → 150–180 ft³

Tips and considerations

Test before you dig

Call 811 (US) before any excavation to mark utilities. Hitting a buried gas, water, or fiber line is dangerous and expensive.

Compaction equipment

Plate compactors handle 2–4 inch lifts of fill. For deeper sections, compact in lifts and add water to bring the soil to optimum moisture.

Common mistakes to avoid

Ignoring soil swell. Excavated dirt expands 20–30% compared to its in-place volume. If your hole is 100 ft³, plan for about 125 ft³ of loose spoil to haul away.
Confusing fill dirt with topsoil. Fill is for structural support; topsoil is for plants. Fill dirt is denser (about 100 lb/ft³ vs 75 for topsoil) and cheaper.
Forgetting compaction for fill jobs. Compacted fill takes 10–15% less volume than the loose dirt you ordered. Order extra.
Underestimating dump-truck capacity. A standard 10-wheeler hauls about 14 cubic yards of dirt — about 380 ft³ per load.