Got three raised beds, all different sizes, and a soil order to place? This raised bed soil calculator different sized beds was built for exactly that: instead of working out one bed, repeating the maths for the next, and hoping your hand-added total is right, you list every bed once and get each volume plus the grand total and bag count in one go.
Raised Bed Soil Calculator — Different-Sized Beds
Add one row per bed. Each bed gets its own length, width and soil depth. The unit you pick applies to every bed.
Conversions used: 1 cu ft = 28.3168 litres · 1 m³ = 35.3147 cu ft = 1,000 litres. This tool totals soil volume only — compost or drainage layers are not included.
How to use this raised bed soil calculator for different-sized beds
Step 1: Pick one unit for all beds
Choose feet or metres once, and use it for every measurement you type. The unit applies to all beds together, so the maths stays consistent.
If you measured some beds in feet and others in metres, convert one set before you start. One metre is 3.28084 feet, and one foot is 0.3048 metres.
Step 2: Add a row for each bed and enter its size and depth
Click Add bed for every raised bed you own. Give each row a name you will recognise, such as Tomato bed or Herb bed.
Type the inside length, the inside width and the soil depth — how deep the soil itself will sit, not the height of the bed walls. Remove a row with Remove if you add one too many.
Step 3: Read the per-bed volumes, the total and the bags
The tool shows each bed’s volume in cubic feet and litres, with the formula length × width × depth written out so you can check it. Below that sits the grand total across all beds.
Bags needed is the total litres divided by your bag size, rounded up — shops do not sell part bags. The bag size box starts at 50 litres; change it to match the bags you buy. Use Copy to grab the numbers or Print for a paper copy.
Worked example: raised bed soil calculator, different-sized beds
Click Load example and the tool fills in three beds that are all different sizes and depths: a Tomato bed at 8 × 4 ft with 1 ft of soil, a Herb bed at 4 × 2 ft with 0.75 ft of soil, and a Salad bed at 6 × 3 ft with 0.5 ft of soil.
Each bed’s volume is length × width × depth. Litres come from cubic feet × 28.3168. The grand total is the sum of the three beds — not one bed multiplied by three.
| Bed | Length × Width | Soil depth | Volume |
|---|---|---|---|
| Tomato bed | 8 × 4 ft | 1 ft | 32.00 cu ft (906.1 L) |
| Herb bed | 4 × 2 ft | 0.75 ft | 6.00 cu ft (169.9 L) |
| Salad bed | 6 × 3 ft | 0.5 ft | 9.00 cu ft (254.9 L) |
| Total | — | — | 47.00 cu ft (1,330.9 L) |
With the default 50-litre bag size, 1,330.9 ÷ 50 = 26.62, so the tool rounds up to 27 bags. Try changing the Salad bed’s depth to 1 ft and watch its volume double to 18.00 cu ft while the grand total moves with it.
More everyday planners from ToolBrewLab: plan laundry by category instead of averages, or find the combined wash temperature for a mixed load.
Common mistakes with different-sized raised beds
Calculating one bed and multiplying
Measure the biggest bed, work out its soil, then multiply by the number of beds. With different-sized beds that quietly over-orders — or worse, leaves the smaller beds short. List each bed separately instead.
Mixing feet and metres
Length in feet, depth in metres, width guessed. Mixed units are the fastest way to a wrong total. Pick one unit for all beds and convert every measurement to it first.
Using the wall height as the depth
People measure length and width carefully, then enter the bed’s wall height as the depth. If you only fill soil to 0.5 ft in a 1 ft tall bed, enter 0.5. Depth means soil depth, not timber height.
Raised bed soil calculator FAQs: different-sized beds
Why does it matter that my beds are different sizes?
Because soil volume grows with every dimension, a bed that is twice as long needs twice the soil — and a deeper bed needs more again. A single-bed calculator forces you to repeat the sum for each bed and add the results by hand, which is where beds get missed or units get mixed. Entering every bed once, each with its own size and depth, gives one checked total instead of a pile of scribbled sums.
How is the soil volume calculated?
Each bed uses length × width × soil depth in the unit you chose. In feet that gives cubic feet directly; in metres it gives cubic metres, which the tool converts at 1 m³ = 35.3147 cu ft = 1,000 litres. Litres for feet-based beds use 1 cu ft = 28.3168 litres. The formula is shown beside every bed so you can verify the maths.
What if I measured some beds in feet and others in metres?
The tool applies one unit to every bed, so convert your measurements to a single unit before typing them in. Multiply metres by 3.28084 to get feet, or multiply feet by 0.3048 to get metres, then enter all beds in the unit you picked.
How does the tool count the bags?
It divides the grand total in litres by the bag size you enter and rounds up to the next whole bag, because you cannot buy part of a bag. The bag size box starts at 50 litres — set it to whatever your local bags hold before you read the number.
Does the tool include compost or drainage layers?
No — it totals soil volume only. If you plan a drainage layer of gravel or a top dressing of compost, work those out separately and add or subtract them from the soil figure yourself.