Easy Garden Calc

How much soil for a 3×6 raised bed?

Short answer

A 3 × 6 ft raised bed 12 inches tall, filled to 1 inch below the rim, holds 16.5 cubic feet of soil. With 10% for settling, buy 18.2 cubic feet: 13 bags of 1.5 cu ft, or 10 bags of 2 cu ft.

How to work it out

  1. Soil depth: 12 in bed − 1 in below the rim = 11 in
  2. 6 ft × 3 ft × 11 in ÷ 12 = 16.5 cu ft (bed volume)
  3. 16.5 cu ft + 10% for settling = 18.2 cu ft
  4. 18.2 cu ft ÷ 1.5 cu ft per bag = 13 bags

Three-foot-wide beds suit a spot against a fence or wall, where you can only reach in from one side. University of Missouri Extension suggests limiting one-sided beds to about 3 ft wide for exactly that reason. Six feet long keeps the bed short enough that the sides rarely need extra bracing.

Adjust for your project

ft
Inside measurement, in feet. 7 ft 6 in = 7.5
ft
Inside measurement
in
Ground to the top of the boards, measured inside. Two 2×6 boards ≈ 11 in · one 2×12 ≈ 11¼ in · three 2×6 ≈ 16½ in
in
Room for water and mulch: 1–2 in is usual. We subtract it for you. 0 = fill to the top
Same-size beds — leave at 1 for one bed
Printed on the bag · raised-bed mix is usually 1–2 cu ft
More options: Settling · Mix · Bag price …
%
10–20% for fluffy bagged mixes
Mixing your own? Pick a recipe to see how much of each to buy, in bags
$
Blank to skip
$per cu yd
From a landscape yard, sold by the half yard (0.5 m³) · blank to skip
Your shopping listBuy 13 bags (1.5 cu ft) of raised-bed mix.
Soil depth (filled)
11 in
Soil to buy
18.2 cu ft (0.67 cu yd)

For this job · affiliate link
Garden dump cart13 bags will come home in the car; a dump cart gets them from the driveway to the bed in a few trips.
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Soil for a 6 ft bed 12 in tall, by width

Soil for a 6 ft bed 12 in tall, by width
WidthSoil to buyBags to buy
2 ft12.1 cu ft9 bags
2.5 ft15.1 cu ft11 bags
3 ft18.2 cu ft13 bags
4 ft24.2 cu ft17 bags

What to know about a 3×6 raised bed

This footprint is 18 square feet, so every inch of soil is 1.5 cubic feet. That makes the arithmetic easy to check: a 12 in bed filled 11 in deep holds 16.5 cu ft, and an 18 in bed filled 17 in deep holds 25.5 cu ft, just under a cubic yard before settling. If you are ordering bulk for a tall 3 × 6, one yard is not quite enough once you add the settling allowance.

Many galvanized metal kits come in roughly this size, often 17 in tall and sometimes with rounded (oval) ends. Rounded ends hold a little less than a true rectangle, so a straight 3 × 6 figure slightly overestimates them. Fill a tall metal bed to an inch or so below the rim and use that as the depth.

A bed against a fence gets less light on one side and dries unevenly. Put taller crops at the back so they don’t shade the rest, and water the fence side deliberately.

For a narrower bed along a path, see How much soil for a 2×8 raised bed. For the full-size bed you can reach from both sides, see How much soil for a 4×8 raised bed 18 inches deep or the standard 12 in version.

Different size? Use the full Raised Bed Soil Calculator.

What you’ll need

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Frequently asked questions

How much soil for a 3×6 raised bed 18 inches deep?

25.5 cubic feet net filled to an inch below the rim (just under a cubic yard), or 28.1 cubic feet with 10% for settling: 19 bags of 1.5 cu ft.

How much soil for a 3×6 metal raised bed kit 17 inches tall?

Filled to about 16 inches, an inch below the rim: 26.4 cubic feet with 10% for settling, or 18 bags of 1.5 cu ft. Oval-ended kits hold a little less.

How much topsoil and compost for a 3×6 bed in a 50/50 mix?

9.08 cu ft of topsoil and 9.08 cu ft of compost (10 bags and 10 bags of 1 cu ft) for an 11 inch fill with 10% for settling.

Other common sizes

Sources