Example 1
- 12 × 8 × 0.15 m
- 1200 kg/m³
- +5% waste
15.12 m³ · 18.14 t
About 150 mm topsoil for a new lawn.
Topsoil requirement calculator
Type length, width, and bed depth. The calculator multiplies the sizes, adds waste, and a mass from topsoil density. A 12 by 8 m lawn 15 cm deep at 1200 kg/m³ and 5% is 15.12 m³ and 18.14 t. A 4 by 2 m bed 30 cm at 1100 kg/m³ and 10% is 2.64 m³ and 2.90 t.
Topsoil ≠ compost ≠ fill dirt. Match density to what you are buying. Related: floor / plot area, gravel.
Results
Length, Width, Depth / thickness and Waste (%). The result shows up here.
How results are calculated
Topsoil requirement counts m³ and tons of garden soil. V = length times width times depth times (1 plus waste). Mass = V times topsoil density. Bags and bulk bags are optional, the same ceil as gravel. Topsoil is the garden surface layer, not fill and not compost alone.
A 12 by 8 m lawn 15 cm deep at 1200 kg/m³ and 5% is 15.12 m³ and 18.14 t. A deeper 4 by 2 m bed 30 cm at 1100 kg/m³ and 10% is 2.64 m³ and 2.90 t. A 20 by 1.5 m strip 10 cm at 1400 kg/m³ and 5% is 3.15 m³ and 4.41 t. Gravel on 10 by 3 m and 10 cm is 3.15 m³ at another density.
Type length, width, and depth in the header unit. Fifteen centimeters is 0.15. Waste, preset, custom density, bulk bag, small bag, and price are optional. Match density to the delivery: dry screened soil is lighter than wet clay soil.
A 12 by 8 m plot is 96 m² on floor area; here you multiply it by 0.15 m. Gravel under a path is a separate card. Sand 1.26 m³ from a 6×4×0.05 m bed does not replace humus.
Moisture moves tons a lot at the same volume. 18.14 t at 1200 kg/m³ is an order estimate. Bags round up. Typing 15 as depth instead of 0.15 orders a hundred times too much.
Type 12, 8, and 0.15, set 1200 and 5%, click Calculate, and match 15.12 m³ and 18.14 t. Then 4, 2, and 0.3 at 10%: 2.64 m³ and 2.90 t.
How to use this calculator
- Type length, width, and depth in the header unit. A 15 cm layer is 0.15, not 15.
- Set waste, usually 5-10%, and topsoil density, for example 1200 kg/m³.
- Optionally enter a bulk bag and bag size if that is how you buy soil.
- Click Calculate. 12×8×0.15 m, 1200 kg/m³, and 5% give 15.12 m³ and 18.14 t.
- Gravel and plot area sit next door. This calculator stays surface soil.
Topsoil 15 cm on 12 by 8 m
A 12 by 8 m lawn 15 cm deep at 1200 kg/m³ and 5% is 15.12 m³ and 18.14 t. A 4 by 2 m bed 30 cm at 1100 kg/m³ and 10% is 2.64 m³.
- topsoil
- Garden soil in the page title. 12 × 8 × 0.15 × 1.05 = 15.12 m³, at 1200 kg/m³ that is 18.14 t for a new lawn.
- m³
- Soil volume. 15.12 on the 12 by 8 m lawn. The 4 by 2 m bed 30 cm at 10% is 2.64 m³, not 1.26 of sand.
- kg/m³
- Topsoil density. 1200 on 15.12 m³ is 18.14 t. Lighter 1100 on 2.64 m³ is 2.90 t on the flower bed.
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
Deeper light soil for flower beds.
Example 3
- 20 × 1.5 × 0.1 m
- 1400 kg/m³
- +5% waste
3.15 m³ · 4.41 t
A strip along a fence - denser fill soil.
Example 4
- 3 × 1.2 × 0.40 m
- 1100 kg/m³
- +5% waste
1.51 m³ · 1.66 t
How much topsoil for a 3×1.2 m raised bed 40 cm deep? 1.51 m³, 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
How much topsoil for an 8 m border 60 cm wide and 30 cm deep? 1.51 m³, 1.81 t.
Related calculators
Frequently asked questions
How much soil for 12×8×0.15 m at 1200 kg/m³ and 5%?
15.12 m³ and 18.14 t. 12×8×0.15 = 14.4, times 1.05, times 1200 kg/m³.
How much at 4×2×0.3 m, 1100 kg/m³, and 10%?
2.64 m³ and 2.90 t. A deeper bed, a lighter preset.
How much at 20×1.5×0.1 m, 1400 kg/m³, and 5%?
3.15 m³ and 4.41 t. A narrow strip along a fence, same length × width × depth.
How do I type a 15 cm depth?
As 0.15 m. Typing 15 would be fifteen meters of soil.
How is topsoil different from 3.15 m³ of gravel?
The same V formula, a different density and use. Gravel 10×3×0.1 m at 1600 kg/m³ is 5.04 t, not humus.
What waste should I add for soil?
Usually 5-10% for settlement and edges. 5% on 14.4 m³ is 0.72 m³.
How many m² is a 12 by 8 m lawn?
96 m² on floor area. The calculator multiplies that by 0.15 m.
Does wet soil change the 18.14 t?
Volume stays. Mass rises with water and clay. Match density to the delivery.
Do bags round up?
Yes. Mass divided by bag size goes through ceil, as with gravel.
Should I type compost as topsoil?
Only if you know its density. The 1200 kg/m³ preset is for surface soil, not light compost.
Knowledge sources
Volume and waste come from the sizes you type. Below are volume and NIST SI units.
Page updated in 2026.