To calculate how much topsoil you need: (Length × Width × Depth in feet) ÷ 27 = cubic yards. For example, a 10’×10′ area filled 6 inches deep needs 1.85 cubic yards. Below: the formula explained, project-by-project examples, conversion charts for inches/feet/yards, and how much to order accounting for settling and waste.
The basic topsoil calculation formula
All topsoil calculations follow this formula:
Cubic Yards = (Length × Width × Depth) ÷ 27All three measurements must be in feet. The “27” comes from the fact that 1 cubic yard = 27 cubic feet (3 ft × 3 ft × 3 ft).
Depth is the trickiest part — it’s almost always measured in inches but needs to be converted to feet for the formula:
- 1 inch = 0.083 feet
- 2 inches = 0.167 feet
- 3 inches = 0.25 feet
- 4 inches = 0.333 feet
- 6 inches = 0.5 feet
- 12 inches = 1 foot
Worked examples for common projects
Filling a raised garden bed (4’×8’×12″ deep)
- Length × Width × Depth: 8 × 4 × 1 = 32 cubic feet
- ÷ 27 = 1.19 cubic yards
- Order: 1.5 cubic yards (allows for settling)
Topdressing a 1,000 sq ft lawn at ½ inch deep
- Area × Depth: 1,000 × 0.042 = 42 cubic feet
- ÷ 27 = 1.56 cubic yards
- Order: 2 cubic yards
New lawn area, 500 sq ft, 4 inches deep
- Area × Depth: 500 × 0.333 = 167 cubic feet
- ÷ 27 = 6.17 cubic yards
- Order: 7 cubic yards
10’×10′ flower bed, 6 inches deep
- Length × Width × Depth: 10 × 10 × 0.5 = 50 cubic feet
- ÷ 27 = 1.85 cubic yards
- Order: 2 cubic yards
Filling a 12′ × 16′ depression averaging 8 inches deep
- Length × Width × Depth: 12 × 16 × 0.667 = 128 cubic feet
- ÷ 27 = 4.74 cubic yards
- Order: 5 cubic yards (for irregular surfaces, round up generously)
Quick reference: cubic yards needed per 100 square feet
| Depth | Cubic Yards per 100 sq ft |
|---|---|
| 1 inch | 0.31 |
| 2 inches | 0.62 |
| 3 inches | 0.93 |
| 4 inches | 1.24 |
| 6 inches | 1.85 |
| 12 inches | 3.70 |
For larger areas, multiply by your area in hundreds. 500 sq ft at 4 inches deep = 5 × 1.24 = 6.2 cubic yards.
How much topsoil to order (accounting for settling)
Always order 10-20% more than your calculation suggests. Three reasons:
- Settling: fresh topsoil compresses over time. A 6-inch fill settles to about 5 inches within 2-3 months
- Irregular surfaces: real-world areas aren’t perfectly flat, so actual volume needed exceeds the math
- Wastage and spread loss: small amounts disappear during loading, hauling, and spreading
Rule of thumb:
- Small projects (under 2 yards): round up to the nearest yard
- Medium projects (2-5 yards): add 10%
- Large projects (5+ yards): add 15-20%
How depth affects how much topsoil you need
Doubling depth doubles your topsoil need. The most common mistake people make is underestimating depth for the project type:
| Project Type | Recommended Depth |
|---|---|
| Topdressing existing lawn | ¼ – ½ inch |
| New lawn (over existing soil) | 2 – 4 inches |
| New lawn (over fill dirt or poor base) | 4 – 6 inches |
| Annual flower beds | 6 – 8 inches |
| Vegetable garden | 8 – 12 inches |
| Raised bed | 12 inches (full depth) |
| Tree planting backfill | 1.5x root ball depth |
| Leveling small depressions | Whatever fills them |
Calculating for irregular shapes
Real beds rarely have perfect rectangular shapes. Approaches:
- Circular beds: π × radius² × depth ÷ 27. For a 10-foot diameter circle (5-foot radius) at 6 inches deep: 3.14 × 25 × 0.5 ÷ 27 = 1.45 cubic yards
- Triangular beds: (base × height ÷ 2) × depth ÷ 27
- Irregular shapes: break into rectangles, triangles, and circles. Calculate each separately, then add
- L-shaped or curved beds: approximate with an enclosing rectangle, then subtract uncovered corners
How many bags of topsoil do you need?
Bagged topsoil comes in 0.75 or 1 cubic foot bags. Conversions:
- 1 cubic yard = 27 cubic feet
- Using 1 cu ft bags: 27 bags = 1 cubic yard
- Using 0.75 cu ft bags: 36 bags = 1 cubic yard
- Using 40 lb bags (most common): roughly 27 bags ≈ 1 cubic yard (varies by moisture)
For more detail, see our how many bags in a yard guide.
Weight considerations when ordering
Knowing topsoil weight helps plan hauling and delivery:
- 1 cubic yard of moist topsoil: ~2,400 lbs (over max payload of most half-ton pickups)
- 1 cubic yard of dry topsoil: ~2,000 lbs (marginal for half-ton pickups)
- 3 cubic yards: 6,000-7,200 lbs (small dump truck territory)
- 5+ cubic yards: definitely needs commercial delivery
See our topsoil weight guide for full weight ranges by moisture and soil type.
Frequently asked questions
How many yards of topsoil do I need for a 1,000 sq ft lawn?
For new lawn at 4 inches deep: 12.3 cubic yards. For topdressing at ½ inch: 1.5 cubic yards. The depth makes a huge difference — be sure of your depth before ordering.
How do I measure depth for an uneven area?
Take 5-10 depth measurements across the area, then average them. For sloped or terraced beds, calculate each section separately.
Is it better to over-order or under-order topsoil?
Slightly over-order. Running short mid-project means an extra delivery fee that often costs more than the saved yard of topsoil. Excess can be used for amending other beds or topdressing later.
How much does a yard of topsoil cost?
Bulk topsoil typically runs $20-50 per cubic yard delivered, with regional variation. Premium blended topsoil with compost runs $40-80 per cubic yard. See our topsoil pricing guide.
Can I buy half a yard of topsoil?
Some suppliers will deliver half yards but with higher per-yard pricing. Others have 1-yard or 2-yard minimums. Bagged topsoil is the easier path for under-1-yard needs.
Find topsoil suppliers near you
Topsoil.com lists over 10,000 verified topsoil suppliers across all 50 states. Browse by state to compare delivery pricing and minimum orders in your area.
Related guides: Cubic Yard Topsoil Weight, Yard of Topsoil Cost, Bags of Topsoil per Yard.
