Soil Calculator
Pick what you are filling, a raised bed, a hole or trench, or a round pot, and type the measurements you actually took: a bed and a fill want a length, a width and a depth, and a pot wants a diameter, a height of mix and how many pots there are. The answer comes back as cubic feet, cubic yards and litres at once, with the bag count under it. The bag size is a field on this page with the common sizes beside it, from 0.75 to 3 cubic feet, rather than a brand we picked for you, because the count is only useful if it matches the sacks you are about to buy. Feet and inches or metres and centimetres, converted without rounding until the last step, and nothing is uploaded or stored anywhere but your own browser.
Soil needed
Cubic feet
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.
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 much soil does a 4 by 8 raised bed need?
- Filled 10 inches deep it takes 26.67 cubic feet, which is 0.99 cubic yards or 755 litres. In bags that is 18 of the 1.5 cubic foot size, 27 of the 1 cubic foot size, or 14 of the 2 cubic foot size, always rounded up because a shop does not sell part of a bag. Fill the same bed 12 inches deep and it is 32 cubic feet, 1.19 cubic yards and 22 bags of 1.5; at 6 inches it is 16 cubic feet and 11 bags. A 4 by 4 bed at 10 inches is 13.33 cubic feet and 9 bags, exactly half the 4 by 8. Those are the figures this page returns, and the depth and the bag size are both fields you can type over.
- How deep does a raised bed need to be?
- Six inches is the shallowest people commonly build for salad leaves and herbs, 10 to 12 inches is the usual depth for a mixed vegetable bed, and 18 inches or more suits deep rooting crops and beds set on a hard surface with nothing to root into below. A bed sitting on open ground gets whatever is underneath it as well, which is why beds built on soil are often shallower than beds built on paving. This page does not choose the depth for you: it takes the one you decided on and gives the quantity, so a 4 by 8 bed reads 16 cubic feet at 6 inches, 26.67 at 10 inches and 48 at 18 inches. The Raised bed page opens at 10 inches as a starting point, and the field is there to be typed over.
- How many bags of soil are in a cubic yard?
- A cubic yard is 27 cubic feet exactly, so it is 27 bags of the 1 cubic foot size, 18 bags of 1.5, 14 bags of 2 once the half bag is rounded up, and 9 bags of 3. Litre sacks work the same way once you convert: a 40 litre sack is 1.41 cubic feet and a 50 litre sack is 1.77, so a cubic yard is 20 of the first or 16 of the second. That is why the bag size here is a field. Type the figure printed on the sack you are buying and the count follows it, and if you are ordering loose by the yard the cubic yards figure is already on the screen beside the cubic feet.
- Is topsoil different from potting mix for this calculator?
- For the arithmetic, no. A volume is a volume: a 4 by 8 bed 10 inches deep holds 26.67 cubic feet of whatever you put in it, topsoil, garden compost, a bagged raised bed mix or a peat free potting mix. What changes between them is the bag, and that is the field on this page. Potting mixes are commonly bagged at 1 or 1.5 cubic feet or in 40 and 50 litre sacks, while topsoil and compost are often sold loose by the cubic yard or in bulk bags, so the same 26.67 cubic feet reads as 18 bags, 27 bags or 0.99 of a yard depending on how you are buying it. The other difference is one no calculator can see: mixes settle by different amounts after the first watering, so check the level again a week later.
- How do I work out the soil for a pot or a planter?
- Switch to Pot and give it the diameter across the top, the height of mix you want in it, and how many pots you are filling. It uses the cylinder formula, pi times the radius squared times the height, so a 12 inch pot with 10 inches of mix is 0.65 cubic feet, or about 19 litres. A 14 inch pot with 12 inches of mix is 1.07 cubic feet, a 16 inch pot with 14 inches is 1.63, and a 20 inch pot with 16 inches is 2.91. Three of those 12 inch pots come to 1.96 cubic feet, which is 2 bags of 1.5. A pot that tapers inward at the base holds a little less than the cylinder, so treat the figure as the top of the range, and remember that a root ball takes up room the calculator cannot see.
- How much soil do I need to fill a hole?
- Switch to Fill and measure it as a rectangle: a hole 3 feet by 3 feet and 2 feet deep is 18 cubic feet, 0.67 cubic yards and 12 bags of 1.5. A trench 20 feet long and 3 feet wide, brought up 4 inches, is 20 cubic feet and 14 bags. A low patch 10 feet by 2 feet needing 6 inches is 10 cubic feet and 7 bags. A hole that is not square is worth splitting into two rectangles and adding the answers, which is more honest than averaging it. Past about a cubic yard, that is 27 cubic feet, bagged soil usually stops being the cheaper way to buy it, and the cubic yards figure on the screen is the one a bulk supplier will quote against.
- Does it work in metres and litres?
- Yes. The Units switch takes the plan in metres and the depth in centimetres, and it rewrites what you have already typed rather than clearing it, to four decimals, so 4 feet becomes 1.2192 metres and 10 inches becomes 25.4 centimetres. Litres are printed for every answer in both systems, since bagged compost outside the United States is sold in litres: a bed 1.2 metres by 2.4 and 25 centimetres deep is 720 litres, and a 30 centimetre pot with 25 centimetres of mix is 18 litres. The bag field itself stays in cubic feet, so convert a litre sack once by dividing by 28.32, or use the 1.41 and 1.77 figures for the 40 and 50 litre sizes.
- Is anything uploaded, and does it cost anything?
- No. The arithmetic runs in your browser, there is no account and nothing is sent anywhere. What you type, the mode, the units and the bag size are kept in your browser's own storage so the page opens where you left it, and clearing your browser data clears that too. The three pages under this one, raised bed, fill and pot, always open in their own mode whatever you last used here, and the raised bed page always opens 10 inches deep; every other setting you had still comes back.
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.