Raised Garden Bed Soil Calculator
Find the soil to fill a raised garden bed. Get litres, bags and cubic yards. Pick garden soil, triple mix or your own mix.
Measure your project
Your answer
That is 1.00 m³. We added 10% extra.
If you buy bags
What it costs
Garden soil: $4 for 25 L (16¢ a litre), from 7 prices at only 3 Ontario stores, Oct 2026. Before tax.
Quick answers
- How deep
- 12 in (300 mm). The University of Saskatchewan says 6–12 in, with 12 in ideal.
- 4 × 8 ft bed, 12 in deep
- 32 cubic feet, or about 906 litres.
- Bags for that bed
- 37 bags of 25 L, or 19 bags of 50 L. No extra added.
- Triple mix
- Topsoil, peat or compost, and manure. The 2 sellers that print a recipe use equal thirds.
- Cost to fill it
- About $148 in garden soil bags at Ontario stores. Loose triple mix is $65 if you pick it up. Before tax.
How to work it out
- Measure inside the bed: length and width in feet.
- Turn the soil depth into feet: inches ÷ 12.
- Multiply the three numbers to get cubic feet.
- Multiply by 28.3 for litres. Divide by the bag size for the number of bags.
8 × 4 × (12 ÷ 12) = 32 cubic feet
32 × 28.3 = 906 litres
906 ÷ 25 = 36.2, so 37 bags of 25 L
How deep to fill a raised bed
Roots need room. These Canadian guides give a depth for food gardens.
| Who | Depth | Note |
|---|---|---|
| University of Saskatchewan | 6–12 in of topsoil | 12 in is ideal |
| Manitoba Master Gardeners | 30 cm | For root vegetables |
| Government of Manitoba | 6 in to 3 ft | Community garden guide |
USask says 12 inches is ideal because many vegetables have deep roots. That is why the calculator starts at 12 inches (300 mm).
USask's lowest depth is 6 inches. Pick it if your bed is short.
Soil for common bed sizes
Store soil is sold by the litre, so this table counts litres and bags. All beds are 12 inches deep.
| Bed | Litres | 25 L bags | 50 L bags |
|---|---|---|---|
| 2 × 4 ft | 227 | 10 | 5 |
| 3 × 6 ft | 510 | 21 | 11 |
| 4 × 4 ft | 453 | 19 | 10 |
| 4 × 8 ft | 906 | 37 | 19 |
| 4 × 12 ft | 1,359 | 55 | 28 |
No extra added. Bags are rounded up.
For a bed 6 inches deep, halve the litres. For 18 inches, add half again.
Filling round pots or a round planter? Tap "Round" on the bed and type the width across.
Triple mix, 4-way mix or bags?
Triple mix
Triple mix is the Ontario name for a garden blend. Yards and stores both sell it, loose or in bags.
The "Mix my own" choice uses the equal thirds that 2 current sellers print. It shows how much of each part to buy.
4-way mix
Manitoba yards sell 4-way mix. One makes it from topsoil, peat, washed sand and manure. Manitoba Master Gardeners say it is good for vegetables.
Bags from the store
Stores sell garden soil, triple mix and raised bed soil. Soil bags in Canada hold 20 to 56.6 litres.
We found no Canadian ratio from a university or garden group. US guides give their own mixes, so we leave them out.
What it costs to fill one bed
Here is the 4 × 8 ft bed, 12 inches deep. It holds 0.91 m³, or 1.19 cubic yards.
| How you buy it | Sum | Cost |
|---|---|---|
| Garden soil, 25 L bags | 37 × $4 | $148 |
| Triple mix, 25 L bags | 37 × $4.93 | $182 |
| Raised bed soil, 50 L bags | 19 × $14.50 | $276 |
| Loose triple mix, picked up | 1.19 yd³ × $55 | $65 |
| Loose triple mix, delivered | plus a $75 fee | $140 |
Before tax, Oct 2026. Bag prices are worked out from each soil's middle price per litre, at Ontario stores only. Raised bed soil: only 1 store. Triple mix bags: only 2 stores. Loose triple mix: 9 yards. Fee: 7 yards.
Loose soil is cheapest if you can pick it up. With a delivery fee, it costs about the same as garden soil bags for this one bed.
Loose triple mix is about 7.2¢ a litre. Garden soil in bags is about 16¢. So the more beds you fill, the more loose soil saves.
One seller also delivers a 1 cubic yard bag of triple mix for $180.
Questions people ask
How many inches of soil does a raised garden bed need?
The University of Saskatchewan says 6 to 12 inches, and 12 is ideal. Manitoba Master Gardeners say 30 cm (12 in) for root crops.
How do I calculate soil for a raised bed?
Multiply the inside length, width and soil depth, all in feet. That is cubic feet. Each cubic foot holds 28.3 litres.
How many bags of soil for a 4 × 8 raised bed?
At 12 in deep, it holds about 906 litres. That is 37 bags of 25 L or 19 bags of 50 L.
What is the best soil for raised garden beds?
We found no Canadian ratio from a university or garden group. USask asks for good topsoil that drains well. Manitoba Master Gardeners say a 4-way mix is good for vegetables.
What is in triple mix?
Topsoil, peat moss or compost, and manure or black loam. Only 2 current Canadian sellers print the amounts. Both say equal thirds.
How do I add soil to a raised garden bed?
Manitoba Master Gardeners suggest filling it a little high, then watering it down. New soil settles.
How long does raised bed soil last?
A yearly top-up of compost or good topsoil is usually enough, says the University of Illinois Extension. Now and then a bed needs more. Clemson Extension also says to add compost regularly.
How much does it cost to fill a raised bed?
About $148 in garden soil bags at Ontario stores, for a 4 × 8 ft bed 12 in deep. Loose triple mix is about $65, plus delivery. Both before tax.
Where our numbers come from
- Topping up raised beds: University of Illinois Extension
- Raised bed compost: Clemson Extension (HGIC)
- Raised beds: University of Saskatchewan gardening guide
- Raised beds: Manitoba Master Gardener Association
- Raised beds: Government of Manitoba, A Community Gardener's Guidebook
- Triple mix: 14 Canadian sellers (contents and prices)
- 4-way soil mix: Anseeuw Bros (Manitoba)
- Weights per cubic yard: Canadian yards and producers (few sources each)
- Store prices: Ontario Home Depot, RONA, Home Hardware and Chamberlain Timber Mart (Oct 2026)
- Bag sizes sold in Canada (soil, mulch)
- Loose prices: the middle of up to 23 Canadian yards (Oct 2026)
- 1 cubic yard bulk bags, delivered: 4 Canadian sellers per product (Garden Bag, Walmart.ca, RONA, Mygardenbag)
- Delivery fees (7 Canadian yards); loads up to 22.9 tonnes (LBL, Almonte ON)
- Unit sizes: NIST Handbook 44, Appendix C (1 ft = 0.3048 m; 1 US gallon = 231 cubic inches)
- Topsoil extra: Palmetto Sand & Gravel (add 10% for settling)
Made by BuildersCount. Last checked 4 Oct 2026.
How we work out our numbers About us Found a mistake? Tell us