E·02 · Garden and outdoors
Soil calculator for topsoil, raised beds and garden beds
Use this soil calculator to work out how much topsoil or raised bed soil you need: enter the length, width and depth to fill and you get the bags to buy or the cubic yards to order.
The plan shows the first area with its dimensions; the section below shows the depth of the layer (not to scale).
What to buy
Your measurements
0.66 m³ of soil: 14 bags
To buy
- 1450 L bag of soil
Estimate only: always go by what the product label says.
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Estimate only: always go by what the product label says.
How much soil do I need?
Volume is length × width × depth. A classic 8 × 4 ft raised bed, 12 in deep, holds 8 × 4 × 1 = 32 cubic feet, or 1.19 cubic yards. The calculator adds up every area, adds an allowance (10% unless you change it) because soil settles after the first waterings, then divides by the size of the bag.
Bagged soil is sold by volume: in the US the usual sizes are 1, 1.5 and 2 cubic feet, in the UK and Europe 40, 50 and 70 litres. The bag size sits in the advanced options: enter the one on the bag you buy.
A worked example
In feet and inches (US). The calculator opens with an 8 × 4 ft raised bed, 12 in deep, 10% extra and 1.5 cu ft bags.
- Volume: 32 cu ft, or 1.19 cu yd
- With 10% extra: 35.2 cu ft
- In 1.5 cu ft bags: 35.2 ÷ 1.5 = 23.5, so 24 bags
In metres (UK and elsewhere). A 2 × 1 m bed, 30 cm deep: 0.6 m³, which is 600 litres, 660 litres with 10% extra, so 14 bags of 50 litres.
Raised bed soil and topsoil: how deep
Fill a raised bed to the top of the frame, usually 12-16 in (30-40 cm). A new garden bed needs about 8 in (20 cm) of soil over loosened ground. To seed a lawn, spread 2-4 in (5-10 cm) of topsoil over levelled ground. For planters, use the inside volume, which some makers print on the box.
Bags or bulk
Bags fit in the car and suit small jobs. Above 1 cubic metre (about 1.3 cubic yards, or some 24 bags of 1.5 cu ft) bulk soil is usually cheaper and comes by truck. The calculator suggests bulk from 1 m³ up, or when you would need more than about forty bags, rounded up to the next half yard.
Common mistakes
- Entering the depth in feet. Depth goes in inches: 12, not 1.
- Forgetting that soil settles. After the first rain, a bed can drop an inch or two: that is what the extra is for.
- Filling a deep raised bed with bagged soil only. The bottom can take coarser material or native soil, with good soil in the top 8 in.
- Mixing up volume and weight. Soil bags are sold by volume, so compare cubic feet, not pounds.
Last reviewed: October 8, 2026 · About us