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Raised bed soil calculator

Enter the bed dimensions to calculate the exact fill volume, bulk cubic yards, bag count, and a source-backed topsoil and compost split.

Step 1

Enter the bed dimensions

Length and width are in feet. Enter the soil depth you plan to fill in inches.

Step 2

Choose a buying plan

A source-backed starting option for a new bed over existing ground.

Your result

Soil to fill this bed

32

cubic feet to order

1.19

cubic yards

22

1.5 cu ft bags

32

square feet of bed

Topsoil
21.3 cu ft
Finished compost
10.7 cu ft

Volume is length x width x depth x number of beds. Mix options come from University of Maryland Extension, Soil to Fill Raised Beds. The source treats these as options based on the site beneath the bed, not one universal recipe.

Compare raised-bed soil Compare raised beds

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<p style="font:14px/1.5 system-ui,sans-serif">Free <a href="https://sproutauthority.com/tools/raised-bed-soil-calculator">Sprout Authority raised bed soil calculator</a> by Sprout Authority.</p>

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What this answer includes

The volume is pure geometry. A 4 by 8 foot bed filled 12 inches deep holds 32 cubic feet before any optional buffer. Bulk suppliers quote cubic yards, while bagged products use cubic feet, so the result keeps both visible.

Choose the mix for the site

The mix presets follow University of Maryland Extension. Beds over soil can use topsoil with compost. Beds on pavement need a lighter compost and soilless growing-media option.

Next decision

Choose materials with the volume in hand

Read the soil guide

Common questions

How do you calculate soil volume for a raised bed?

Multiply length in feet by width in feet, then multiply by soil depth in feet and the number of identical beds. Divide inches of depth by 12 before multiplying. The result is cubic feet.

How many cubic feet are in a cubic yard?

One cubic yard contains 27 cubic feet. The calculator shows both units so you can compare bagged material with bulk delivery.

What soil mix should I use in a raised bed?

University of Maryland Extension lists two parts topsoil to one part compost or equal parts topsoil and compost for beds over existing ground. For a bed on a hard surface, it lists equal parts compost and soilless growing media.

Should I order extra soil?

The exact geometry is the starting volume. The optional 10% buffer is a purchasing allowance for settling and spillage, not a horticultural requirement. Leave it off when the supplier already builds a buffer into the estimate.