Compost Calculator
How many bags of compost do I need?
Compost tops up beds, fills raised beds and mulches borders, and comes mostly in 50 litre bags. Enter the length and width of the area and how deep you want the layer, and the calculator gives the volume in litres and the number of bags, based on your bag size. A depth of around 50 mm is typical for compost.
Bagged products vary between 50 litre bags and larger bulk bags, so set the bag size to whatever your supplier sells. As with any loose material, round up: it settles once walked on or watered in.
Frequently asked questions
Is the compost calculator free?
Yes. It is completely free, with no sign-up and nothing to install. It runs entirely in your browser.
How accurate is it?
It gives a reliable estimate for ordering based on standard UK figures, but real quantities vary with ground conditions, wastage and how materials settle. Always add a margin and confirm with your supplier before buying.