About the Mulch & Topsoil Calculator
The Mulch & Topsoil Calculator works out the volume of garden material you need from a simple length × width × depth. It also estimates the weight (so you know what your delivery truck or wheelbarrow has to handle) and converts between metric and US units.
Recommended depths
- Mulch / bark: 5–8 cm (2–3 in) for weed suppression and moisture retention
- Topsoil: 10–15 cm (4–6 in) for new lawns; 5 cm for top-dressing
- Compost: 2–5 cm (1–2 in) blended into the top layer
- Gravel: 5 cm (2 in) for paths, 10 cm (4 in) for parking areas
Frequently Asked Questions
Bulk or bags? Bagged is convenient for < 1 m³. Above that, bulk delivery is much cheaper per cubic metre.
Should I add a waste factor? Yes — typically 5%. Mulch settles 10–15% in the first month, so order slightly more if you want lasting depth.
Important Note: Estimates only. Density varies between products and suppliers; check your supplier's product data sheet for precise figures.
Related Calculators
- Concrete Calculator — Volume of concrete needed for slabs, footings, columns and post holes. Cubic metres, cubic yards and bag count.
- Tile, Paint & Flooring Calculator — Tiles, litres of paint or boxes of flooring needed for any room — with built-in waste allowance.
- Square Footage Calculator — Floor or land area for rectangles, triangles, circles and trapezoids. Converts m², ft², yd², acres and hectares.