Soil Calculator UK — Topsoil in m³ & Bulk Bags

Real-world example

Two 2.4 × 1.2 m beds filled 300 mm deep

1. Convert the depth: 300 mm ÷ 1,000 = 0.300 m.
2. One bed holds 2.4 m × 1.2 m × 0.300 m = 0.864 m³.
3. Two identical beds hold exactly 1.728 m³.
4. A user-selected 10% settling/handling allowance adds 0.1728 m³, making 1.9008 m³ before purchasing-unit rounding.
5. At an entered loose-bulk increment of 0.25 m³, round 1.9008 m³ up to a 2.000 m³ loose order. Increment rounding adds 0.0992 m³.
6. If the selected supplier states 750 L (0.750 m³) per bulk bag, 1.9008 ÷ 0.750 = 2.53, so the alternative is 3 whole bulk bags containing a stated 2.250 m³ in total.

For these entered assumptions, compare a 2.000 m³ loose order with 3 × 750 L bulk bags. The 10% allowance, 0.25 m³ increment and 750 L package are editable example inputs, not universal UK supplier sizes.

Before you start

How to measure

• Measure each bed's inside length and width at the soil line in metres. Do not use the larger outside dimensions of sleepers, boards, brick or block walls.
• Measure only the empty depth that will receive the selected soil, preferably in millimetres. Deduct reliable existing fill, false bottoms, drainage structures or other occupied space rather than using the full wall height.
• The bed-count field assumes identical beds. Calculate different lengths, widths or fill depths separately and add their checked cubic-metre volumes.
• Choose the fill depth and soil specification for the plants and assembly rather than copying the worked example. RHS guidance says appropriate raised-bed depth depends on what will grow there and explains that deep beds can use lower layers that reduce the quantity of good soil needed.
• For loose delivery, ask the supplier for the quoted unit, minimum order, actual m³ increment, loose/dumped convention, vehicle and offload method. Do not type an order stated only in tonnes into an m³ field.
• For packaged soil, enter the exact volume printed or published for that product—such as litres per small bag or stated litres/m³ per bulk bag. The words “bulk bag”, “jumbo bag” and a bag weight do not establish one standard volume.
• Check delivery access before ordering. A pallet truck needs a suitable firm, level route; kerbside or tail-lift delivery may not put bulk bags beside the bed.
• Inspect the product specification and suitability separately from its quantity. RHS advises checking topsoil for unwanted roots, weeds, stones and contaminants; a volume result cannot certify soil quality.

Local guidance

Notes for United Kingdom

• This UK page defaults to metres for length, millimetres for depth, cubic metres for loose topsoil, litres for bag or bulk-bag volume, GBP and optional user-entered VAT.
• RHS lists topsoil as available in bags or bulk, distinguishes premium, general-purpose and economy grades, and advises inspection before buying. Quantity and product suitability remain separate decisions.
• A current Rolawn product page illustrates why volume must be entered rather than inferred: it describes standard and large bulk bags as approximately 500 L (0.5 m³) and 750 L (0.75 m³), while other UK suppliers sell different packages or loose loads.
• Rolawn's calculator uses length and width in metres and depth in millimetres, then reports calculated m³ and whole 500 L or 750 L bags. This calculator retains that useful unit workflow but lets you enter any supplier's stated volume.
• British Sugar TOPSOIL illustrates a different purchasing route: loose tipper loads or bulk bags with stated minimum quantities. Confirm the selected supplier's actual sale unit and minimum instead of assuming all UK topsoil is packaged alike.
• Where a specification calls for BS 3882 topsoil, verify the current product analysis and project requirement with the supplier. Mention of the standard does not mean every bag is suitable for every garden or planting use.