How this is calculated
Volume is length × width × depth in consistent units. Imperial jobs convert cubic feet to cubic yards (÷ 27). Metric jobs stay in cubic metres when depth is in centimetres.
Weight is only a planning figure. Wet clay topsoil and dry sandy loam do not weigh the same. Use your supplier’s coverage chart when you have a product name.
Formula & methodology
Volume = L × W × D. yd³ = ft³ ÷ 27. Planning weight ≈ yd³ × 1.1 tons (US) or m³ × 1.3 tonnes (UK). Apply waste % for settlement.
Worked example
A 20 ft × 10 ft bed, 4 in deep, 10% waste
- 1.Depth in feet: 4 ÷ 12 = 0.333 ft
- 2.Volume = 20 × 10 × 0.333 = 66.7 ft³
- 3.Cubic yards = 66.7 ÷ 27 = 2.47 yd³
- 4.With 10% waste ≈ 2.72 yd³ (~3.0 tons at 1.1 tons/yd³)
Frequently asked questions
How deep should topsoil be for a new bed?
Many planting beds are planned around 4–6 inches (10–15 cm) of quality topsoil over improved subgrade. Vegetables and deep-rooted shrubs may want more. Lawn topdressing is usually only ½–1 inch.
Is fill dirt the same as topsoil?
No. Fill dirt is cheaper subsoil for raising grade. Topsoil has organic matter for planting. Do not plant into raw fill and expect the same result.
Why add a waste percentage?
Soil settles, grades are uneven, and truck loads are sold in whole yards. 5–10% keeps you from finishing a bed half an inch short.
Bags or bulk delivery?
Bagged topsoil works for small patches. Once you pass roughly a cubic yard, bulk delivery is usually cheaper if you have a place to tip.
Does this include compost or mulch?
No. Compost mixes and mulch cover are separate orders. Use the Mulch Calculator for bark depth on top of the bed.
US and UK units?
Toggle feet/inches or metres/centimetres. Cost currency follows the unit system.
Last updated 2026-09-12. Formulas are planning methods — confirm with a supplier before you order.