Raised Bed Soil Calculator

Work out how much soil to buy from three measurements. Get whole bags, cubic feet and cubic yards, with no account needed.

Measure inside your bed

Use the depth of new soil you want to add, leaving out existing soil or filler.

Measurements

Quick start with a common bed size:

Inside length (ft)

Inside width (ft)

Soil depth to add (in)

The 12-inch starting depth is an example. Change it to the depth you intend to fill.

Bag size, extra soil & price

The quick estimate uses one bed, 2 cu ft bags and no extra material.

Volume printed on each bag

Number of identical beds

Extra material (%)

Price per bag (US$, optional)

Use the bag’s volume, not its weight. Add an allowance only if it suits your project. Price estimates exclude delivery, tax and unentered charges.

Enter your measurements, or choose a bed size above.

How much soil does a raised bed need?

Measure the inside of the frame. Multiply length by width, then by the depth of soil you will actually add. Convert inches to feet before multiplying:

Cubic feet = length (ft) × width (ft) × soil depth (in) ÷ 12

Divide cubic feet by 27 for cubic yards. To find bag quantity, divide the soil volume by the volume on the bag and round up to a whole bag.

A 4 × 8 bed, worked out

At 12 inches deep: 4 × 8 × 12 ÷ 12 = 32 cubic feet.

That is about 1.19 cubic yards, 16 bags of 2 cu ft, or 22 bags of 1.5 cu ft. These figures include no extra material.

My bed already contains soil or logs. What do I enter?

Enter only the depth left for the new soil. For example, topping up an 8 × 4 ft bed by 3 inches requires 8 cubic feet before any allowance. The calculator does not subtract a separate filler layer for you.

Can I calculate several beds?

For beds with identical inside measurements and fill depth, open the optional settings and change the number of beds. For different sizes, calculate each bed separately and add the unrounded volumes before deciding your final order.

Should I add extra for settling?

Fresh material may settle, but the amount depends on your mix and how it is placed. No extra is added automatically. You can enter an allowance in the optional settings; the result shows the percentage used.

Can I use a bag labelled only in pounds?

Find the bag’s cubic-foot or litre volume, or ask the supplier. Weight alone is not enough to calculate volume because moisture and the soil mix change its density.

This tool estimates a rectangular fill volume. It does not select a soil recipe, plant-specific depth, drainage system or vehicle load limit. Your measurements stay in this browser; they are not uploaded or stored as a project history.

Formula and measurement references: Eartheasy’s soil-volume guide and The Old Farmer’s Almanac soil calculator.

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