Soil Calculator: How Much Topsoil, Fill Dirt, or Mulch Do You Need?

Topsoil, fill dirt, mulch, and compost are all sold by the cubic yard, but suppliers sometimes quote in tons (especially for heavier fill materials). The conversions and coverage estimates aren't obvious, and ordering too little means expensive second deliveries while too much leaves you with unwanted piles.

The CalcHub Soil Calculator calculates cubic yards needed for any area and depth, and converts to tons based on material type.

The Core Formula

Volume (cubic yards) = Length (ft) × Width (ft) × Depth (inches) ÷ 324

(324 = 27 cubic feet/yard × 12 inches/foot)

For a garden bed 20 ft × 8 ft × 6 inches deep:
20 × 8 × 6 ÷ 324 = 2.96 cubic yards — order 3 yards.

Material Weights: Cubic Yards to Tons

Material	Weight per Cubic Yard	Notes
Topsoil (dry)	1.0–1.2 tons	Varies with moisture and organic matter
Topsoil (wet)	1.5–1.7 tons	Much heavier when saturated
Fill dirt/subsoil	1.1–1.3 tons	Dense, less organic matter
Screened topsoil	0.9–1.1 tons	Lighter, better tilth
Compost	0.6–0.8 tons	Very light, fluffy
Mulch (wood chips)	0.3–0.5 tons	Very light
Gravel/crushed stone	1.3–1.6 tons	Heavy; see gravel calculator
Sand	1.2–1.4 tons	Varies with moisture

Recommended Depths by Application

Application	Material	Recommended Depth
New lawn establishment	Topsoil	4–6 in
Lawn top-dressing	Topsoil/compost	½–1 in
Raised vegetable garden	Topsoil + compost mix	12–18 in
Flower bed/annual planting	Topsoil	6–8 in
Tree ring mulching	Wood chip mulch	2–4 in
Path/walkway mulch	Wood chips	3–4 in
Grading/low spots	Fill dirt	As needed
Drainage fill	Topsoil	4–6 in slope toward drain

Project Examples

Scenario 1: New lawn area, 50 ft × 30 ft, 6 inches of topsoil 50 × 30 × 6 ÷ 324 = 27.8 cubic yards — order 28 yards of screened topsoil Scenario 2: Eight 4×8 raised garden beds, 12 inches deep Each bed: 4 × 8 × 12 ÷ 324 = 1.19 cubic yards Total: 8 × 1.19 = 9.5 cubic yards

A good raised bed mix is often 1/3 topsoil, 1/3 compost, 1/3 coarse perlite or vermiculite. Order separate materials and combine in the bed.

Scenario 3: Mulching beds around a house, 3 ft wide border × 120 LF perimeter, 3" deep 120 × 3 × 3 ÷ 324 = 3.3 cubic yards of mulch

Delivery Options

Volume	Best Option	Notes
Under 1 yard	Bagged product	Expensive per yard, but no delivery min
1–5 yards	Small local landscape delivery	Most landscapers deliver minimums of 1–3 yards
5+ yards	Dump truck delivery	More economical; verify site access
10+ yards	Call for bulk pricing	Often significant per-yard discount

One cubic yard roughly fills a standard pickup truck bed level — if you have a truck, smaller loads are manageable that way.

Topsoil Quality

Not all topsoil is equal. "Fill dirt" or "subsoil" is cheap but nutrient-poor — fine for grading but not for planting. Screened topsoil has rocks and large debris removed. "Premium" or "garden mix" topsoil includes compost blended in. If you're establishing a lawn or planting beds, pay the premium for screened or amended topsoil.

How do I calculate for an irregular-shaped area?

Break the area into simpler shapes (rectangles, triangles, circles), calculate each section's area, add them together, then apply the depth formula. The calculator has a multi-section mode for exactly this.

How much does a cubic yard of topsoil cost?

Delivered bulk topsoil typically runs $30–$60 per cubic yard for basic screened topsoil, $50–$80 for premium blended topsoil/compost mix. Mulch runs $30–$50 per yard. Prices vary significantly by region.

My area has low spots — should I fill with topsoil or fill dirt?

For areas that need significant fill (more than 4 inches to get grade), use inexpensive fill dirt or subsoil for the bulk of the fill, then top-dress with 4–6 inches of good topsoil for the planting zone. All-topsoil fill for large areas is unnecessarily expensive.

Related Tools

• Gravel Calculator — aggregate and drainage stone
• Land Area Calculator — calculate your area before ordering
• Concrete Calculator — if you're filling and then building