Example 1
- 12 × 8 × 0.15 m
- 1200 kg/m³
- +5% waste
15.12 m³ · 18.14 t
How much topsoil for a 12×8×0.15 m lawn? ×5% at 1200 kg/m³ → 15.12 m³ (18.14 t).
Topsoil Calculator
Enter length, width, and bed depth. The calculator multiplies the three sizes, adds waste, and a mass from density. A 12×8 m lawn 15 cm deep at 1200 kg/m³ and 5% is 15.12 m³ and 18.14 t. A 4×2 m bed 30 cm at 1100 kg/m³ and 10% is 2.64 m³ and 2.90 t.
Results
Enter length, width, depth or thickness, and waste. The result shows up here.
The calculator estimates garden topsoil volume and tonnes. Topsoil is not compost alone and not bulk fill. Related: gravel, floor area.
How results are calculated
L×W×D12×8×0.15
Waste5%
ρ1200
V15.12 m³
The topsoil calculator finds volume and tonnes. The formula is length × width × depth × (1 + waste/100). Mass is V × density. Bulk bags and small bags round up when you fill those fields. Topsoil is growing soil, not compost alone and not bulk fill dirt.
A 12×8 m lawn 15 cm deep at 1200 kg/m³ and 5% is 15.12 m³ and 18.14 t. A 4×2 m bed 30 cm at 1100 kg/m³ and 10% is 2.64 m³ and 2.90 t. A 20×1.5 m strip 10 cm at 1400 kg/m³ and 5% is 3.15 m³ and 4.41 t.
Enter length, width, and depth in the header unit. Fifteen centimeters is 0.15, not 15. Waste, density setting, custom density, bulk bag, small bag, and price are optional. A comma in 0.15 works the same as a period.
Gravel and sand use the same field layout with different typical densities. A 12×8 m plot is 96 m² on the floor-area page; here you multiply it by depth. Sand at 1.26 m³ from a paving bed does not replace humus.
Moisture changes tonnes a lot at the same volume. The mass result is an estimate: 18.14 t at 1200 kg/m³ can drop or rise after rain. Bags round up.
Enter 12 m, 8 m, and 0.15 m at 1200 kg/m³ and 5%: 15.12 m³ and 18.14 t. Then 4 m, 2 m, and 0.3 m at 1100 kg/m³ and 10%: 2.64 m³ and 2.90 t.
How to use this calculator
- Enter length, width, and depth in the header unit. A 15 cm bed is 0.15, not 15.
- Set waste, usually 5–10%, and density from a setting or your own kg/m³, for example 1200.
- Optionally enter bulk-bag volume and bag size if you buy in packs.
- Click Calculate. 12×8×0.15 m, 1200 kg/m³, and 5% give 15.12 m³ and 18.14 t.
- Use the related calculators for gravel and floor area. This page calculates garden topsoil only.
Formula
V = length × width × depth × (1 + waste/100)
mass = V × density
12×8×0.15 m at 5% and 1200 kg/m³: V = 15.12 m³, mass = 18.14 t. A 4×2×0.3 m bed at 1100 and 10% is 2.64 m³ and 2.90 t.
Bed and density
Volume is three sizes × (1 + waste), and mass comes from density. A 12×8 m lawn 15 cm deep at 1200 kg/m³ and 5% is 15.12 m³ and 18.14 t.
- m³
- Volume. 12 × 8 × 0.15 × 1.05 = 15.12. A 4×2×0.3 m bed at 1100 and 10% is 2.64 m³.
- kg/m³
- Density. 1200 on 15.12 m³ is 18.14 t. Light 1100 on 2.64 m³ is 2.90 t.
- t
- Tonnes = V × density ÷ 1000. 15.12 × 1200 = 18.14 t.
- 0.15
- 15 cm in meters. Entering 15 instead of 0.15 overstates the result a hundred times.
Practical tips
- Lawn: often about 100-150 mm of quality topsoil over prepared subgrade.
- Beds: often 200-300 mm - volume rises quickly with depth.
- Levelling: enter average fill depth; split large slopes into zones.
Usage examples
Example 2
- 4 × 2 × 0.3 m
- 1100 kg/m³
- +10% waste
2.64 m³ · 2.90 t
A 4×2×0.30 m bed ×10% at 1100 kg/m³ → 2.64 m³ (2.90 t).
Example 3
- 20 × 1.5 × 0.1 m
- 1400 kg/m³
- +5% waste
3.15 m³ · 4.41 t
A 20×1.5×0.10 m strip ×5% at 1400 kg/m³ → 3.15 m³ (4.41 t).
Example 4
- 3 × 1.2 × 0.40 m
- 1100 kg/m³
- +5% waste
1.51 m³ · 1.66 t
3 × 1.2 × 0.40 × 1.05 = 1.51. That is 1.66 t.
Example 5
- 15 × 4 × 0.10 m
- 1200 kg/m³
- +8% waste
6.48 m³ · 7.78 t
How much topsoil to resurface a 15×4 m lawn at 10 cm? 6.48 m³, 7.78 t.
Example 6
- 6 × 3 × 0.25 m
- 1100 kg/m³
- +10% waste
4.95 m³ · 5.45 t
How much light soil for a 6×3 m vegetable patch 25 cm deep? 4.95 m³, 5.45 t.
Example 7
- 10 × 8 × 0.08 m
- 1400 kg/m³
- +5% waste
6.72 m³ · 9.41 t
How much denser fill to level 10×8 m by 8 cm? 6.72 m³, 9.41 t.
Example 8
- 8 × 0.6 × 0.30 m
- 1200 kg/m³
- +5% waste
1.51 m³ · 1.81 t
8 × 0.6 × 0.30 × 1.05 = 1.51. That is 1.81 t.
Related calculators
Frequently asked questions
How do I calculate topsoil from length, width, and depth?
Multiply the three sizes in meters, add waste, then multiply by density. 12×8×0.15 × 1.05 → 15.12 m³; at 1200 kg/m³ that is 18.14 t.
How many m³ and tons for a 12×8×0.15 m lawn at 1200 kg/m³ and 5%?
15.12 m³ and 18.14 t. A 4×2×0.30 m bed at 1100 kg/m³ and 10% is 2.64 m³ and 2.90 t.
How is topsoil different from sand, gravel, or fill dirt?
The L×W×depth formula is the same as sand and gravel, but density and this page target garden topsoil. Structural fill-dirt cut/fill design is outside this tool.
Does the result replace a datasheet or a weighbridge?
No. It is an estimate from volume and density. Wet soil weighs more at the same volume.
Is this a free topsoil calculator?
Yes. Enter bed sizes and density and you see m³ and tons at once. No account required.
How is topsoil volume calculated?
The calculator multiplies length, width, and depth, then by (1 + waste/100). 12×8×0.15 m at 5% is 15.12 m³. Mass at 1200 kg/m³ is 18.14 t.
Which unit should I use for a 15 cm bed?
Enter 0.15 m in metric. Entering 15 instead of 0.15 would inflate the result a hundredfold.
What waste should I add?
Usually 5–10% for settlement and edges. At 12×8×0.15 m, 5% waste lifts volume from 14.40 m³ to 15.12 m³.
What does the density setting do?
It sets kg/m³: screened light ≈ 1100, standard ≈ 1200, compacted / fill ≈ 1400. A custom density overrides the setting. Volume stays; mass changes.
How is this different from gravel?
The V formula is the same; the material is not. Gravel on 10×3×0.1 m at 1600 kg/m³ and 5% is 3.15 m³ on the gravel page. Here you count garden topsoil.
Does wet soil change 18.14 t?
Volume stays. Mass rises with water and clay. 1200 kg/m³ is a standard-topsoil order of magnitude, not the weight after rain.
How are bulk bags and small bags counted?
Bulk bags: round up V ÷ bulk-bag volume. Bags: mass ÷ bag size, rounded up. Empty fields leave volume and tonnes only.
Can I enter compost as topsoil?
Only when you know its density. The 1200 kg/m³ setting is for garden topsoil, not light compost.
What is the primary result?
Volume with waste, for example 15.12 m³. Tonnes and mass appear beside it after density. Bulk bags, bags, and cost are optional.
Does the result replace a datasheet?
No. The calculator is a purchase estimate. Moisture and settlement on site may need an adjustment.
Knowledge sources
Bed volume is three sizes × (1 + waste). Density comes from a setting or the supplier data. Units below come from NIST.
Page updated October 12, 2026.