Compost & Topsoil Calculator

How many bags of compost, topsoil or gravel do you need? Calculate by bed area and depth — for raised beds, borders or a new lawn.

Area length (m)

Area width (m)

Depth needed (cm)

Material

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Fill in the details to get your calculation.

Raised bed kits include everything you need — timber, fixings and an easy-assemble design.

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How This Is Calculated

Volume = length × width × depth. This is converted to litres (1 m³ = 1000 litres) and divided by the bag volume. Bulk bags (typically 800L–1000L) are far more cost-effective for large areas — compare cost per litre before buying.

Not directly — compost is too nutrient-rich and often too light to use as the primary growing medium. Mix compost 50/50 with topsoil for borders and raised beds. For topdressing lawns, use a specific lawn topdressing mix. Pure compost settles and can cause waterlogging in heavy rains.