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Raised Bed Soil Calculator

A 4 foot by 8 foot raised bed filled 10 inches deep takes 26.67 cubic feet of soil, which is 0.99 cubic yards, 755 litres, or 18 bags of the 1.5 cubic foot size once the part bag is rounded up. This page always opens as a raised bed 10 inches deep, with that example in the fields the first time you land on it, so type your own length, width and depth over it and the cubic feet, the cubic yards, the litres and the bag count all follow. The bag size is a field here, not a brand we assumed: 27 bags at 1 cubic foot, 18 at 1.5 and 14 at 2 are all the same bed, and only the sack changes. It works in feet and inches or in metres and centimetres, and the depth is yours to set, because a bed on open ground and a bed on paving are not the same job.

10 in of soil4 ft × 8 ft raised bed
Soil needed4 ft by 8 ft at 10 in
Cubic feet26.670.99 cu yd · 755 litres18 bags at 1.5 cu ft, rounded up
Mode
Length ft
Width ft
Depth in
Bag cu ft
Units
Common bag sizes

The bag size is a field because it is the one number a brand decides: bagged soil and compost are sold at anything from 0.75 to 3 cubic feet, and 40 litre and 50 litre sacks work out at 1.41 and 1.77 cubic feet. Type what is printed on yours and the count follows. Switching between feet and metres rewrites what you already typed into the other system, to four decimals, rather than clearing it, and the volume is then worked from the figures on the screen.

  • A 4 by 8 raised bed10 in of mix, /soil-calculator/raised-bed
    26.67 cu ft · 18 bags
  • A hole to fill3 ft by 3 ft, 2 ft deep, /soil-calculator/fill
    18.00 cu ft · 12 bags
  • A 12 in round pot10 in of mix, /soil-calculator/pot
    0.65 cu ft · 1 bag
Exact on the shape you describe, and it says so about the rest. Exact arithmetic on what you enter: length by width by depth, or the cylinder formula for a pot, converted without rounding until the last step. It cannot know how far soil settles after its first watering, how much room root balls take, or what a brand actually puts in a bag. There is no price here and no supplier, and no allowance is folded in behind the figure: if you want a margin for settling, raise the depth a little and watch the number move.

Common questions

How many bags of soil for a 4 by 8 raised bed?
At 10 inches deep the bed holds 26.67 cubic feet, so it is 18 bags of 1.5 cubic feet, 27 bags of 1 cubic foot, or 14 bags of 2 cubic feet, each rounded up because part of a bag is not something a shop sells. Fill it 12 inches deep instead and it is 32 cubic feet, which is 22 bags of 1.5. In litre sacks, 40 litres is 1.41 cubic feet and 50 litres is 1.77, giving 19 and 16 bags for the 10 inch fill. Type the figure printed on your own sack into the bag field and the count is worked from that.
How much soil does a 4 by 4 or a 2 by 8 bed take?
Both are half the area of a 4 by 8, so at 10 inches deep both take 13.33 cubic feet, 0.49 cubic yards or 378 litres, which is 9 bags of 1.5 cubic feet. A 4 by 8 bed at the same depth is 26.67 cubic feet and 18 bags. The arithmetic is length times width times depth, so doubling any one of the three doubles the soil, and the page prints the figures for whatever three you type.
How deep should I fill a raised bed?
This page opens at 10 inches, which sits in the middle of what people commonly build. Six inches is the shallow end, enough for salad leaves and herbs; 10 to 12 inches is the usual depth for a mixed vegetable bed; 18 inches and up suits deep rooting crops and beds standing on paving with nothing to root into underneath. A bed sitting on open soil borrows the ground below it, which is why those beds are often built shallower. The depth is a field, not a recommendation: the same 4 by 8 bed reads 16 cubic feet at 6 inches, 26.67 at 10 and 48 at 18.
Should I add extra soil for settling?
The figure here is the volume of the box as you described it, with nothing added behind your back. Soil and compost do drop after the first heavy watering, and how far depends on the mix, how firmly it went in and what is underneath, none of which this page can see from your measurements. If you want a margin, raise the depth by an inch and watch the number move: on a 4 by 8 bed that is 2.67 cubic feet, or two more bags of 1.5. Filling a little short and topping up a week later is the other way people do it.
Is it cheaper to buy bags or a bulk load?
The number that decides it is the cubic yards figure printed beside the cubic feet, because bulk suppliers quote by the yard and bags are priced by the bag. A 4 by 8 bed at 10 inches is 0.99 cubic yards, so it is right on the line: 18 bags, or one yard delivered. Two or three beds of that size push you past two yards and bags usually stop competing. The page gives you both units from the same measurement, and it does not carry prices, because a price is local and it moves.

Exact arithmetic on what you enter: length by width by depth, or the cylinder formula for a pot, converted without rounding until the last step. It cannot know how far soil settles after its first watering, how much room root balls take, or what a brand actually puts in a bag.