Gardening
Garden Soil Calculator
Bed length, width and depth — litres, bags and an optional bulk m³.
How much soil for a bed?
Raised beds are often filled with 20–30 cm of compost or topsoil. Bags are sold in litres; bulk is cubic metres — and 1 m³ is 1,000 litres. Enter bed dimensions and depth to estimate volume, then add a little extra for settling after rain and watering. Mixed vegetable beds may want greater depth for root crops; shallow herb troughs need less. For other volume DIY see concrete calculator. Mulch layers on top are a separate shallow volume if you order them too. Delivery access for bulk bags matters as much as price per litre. This is a materials estimate, not agronomic or contamination advice. Weed-free topsoil and peat-free compost blends price differently per litre — compare on the same volume basis after this estimate. Avoid blocking drains with fines washed from fresh soil after the first heavy rain; leave a freeboard below the bed rim. If you mix your own blend, total the component volumes rather than guessing the final fill.
Worked example
A raised bed 2.4 m × 1.2 m filled 25 cm deep: volume = 2.4 × 1.2 × 0.25 = 0.72 m³ (720 litres). Adding about 10% for settling suggests roughly 800 litres — sixteen 50 L bags, or a bulk order if you have several beds. Halving depth to 12.5 cm for a shallow planter cuts the order to about 0.36 m³ before waste.
Limits and assumptions
Assumes a rectangular box. Tapered walls and already partly filled beds need adjusted depth. Soil type recommendations (topsoil vs compost blends) are outside the calculator.
Frequently asked questions
How deep should raised bed soil be?
Many vegetables prefer 20–30 cm or more. Root crops appreciate greater depth — check your crop list.
Bags or bulk loose soil?
Small beds suit bags; larger projects usually win on price with bulk once you can take delivery.
Why add extra for settling?
Organic mixes compact after rain and watering. A small over-order avoids a second delivery fee.
How many litres in a cubic metre?
1,000 litres. Convert bulk quotes and bag counts onto the same unit before comparing price.
Can I reuse old soil?
Sometimes with conditioning — volume available still matters. Contaminated or pest-ridden soil needs separate judgement.