Cubic metres of soil or mulch for a garden bed.
Free to use, no sign-up required. Soil Estimator is one of 198 tools built into Xenition, alongside a chat that can use them for you.
Calculates how much topsoil, compost, mulch or potting mix fills a garden bed, as a volume, a rough weight and a count of 50 L bags.
Volume = length × width × (depth ÷ 100) in m³, and litres = m³ × 1,000. Bags = litres ÷ 50, rounded up. Weight = volume × an approximate dry bulk density: topsoil 1,400 kg/m³, compost 550, mulch 400 and potting mix 450.
A bed 3 m × 2 m filled 15 cm deep holds 0.9 m³, or 900 litres, which is 18 bags of 50 L. As topsoil that weighs about 1,260 kg; as mulch, about 360 kg.
Around 5 to 8 cm is typical for suppressing weeds and holding moisture. New beds and raised beds are usually filled with 15 to 30 cm of soil or compost.
Soil density changes a lot with moisture and how compacted it is. Wet topsoil can weigh noticeably more than the dry figure, which matters for trailer loads and roof gardens.
You do not have to open Soil Estimator to use it. Ask Xenition in plain language and it runs the right tool, then carries the answer into whatever you are working on — a document, a spreadsheet, a deck.