Enter each raised bed length, width and fill depth to get the soil volume in litres, cubic feet or cubic yards - plus how many bags to buy. Add a bed for each one you are filling. Works in feet/inches or metres/centimetres.
Typical depths: 50–75 mm (2–3 in) for mulch, 40–50 mm for decorative gravel, 100 mm (4 in)+ for new topsoil, deeper again to fill a raised bed. Each area can take its own depth.
Enter the delivered price per m³ of bulk material to get the total.
Total bed area
10.00 m²
In litres
500 L
A raised bed is filled to a depth, so the soil you need is the bed area times the fill depth:
volume = length × width × fill depth
Filling several beds? Add a bed for each one - the calculator totals the volume and rounds the bag count once for the whole order, and it shows a per-bed breakdown so you can see where the soil is going. All math runs in exact metric internally, so switching units never changes the answer.
This example follows the unit system you pick in the calculator above.
One 1.2 m × 2.4 m raised bed filled 300 mm deep, from 50-litre bags:
Split the total volume from the calculator by your chosen mix:
| Mix | Ratio | Good for |
|---|---|---|
| Standard veg mix | 60% topsoil · 30% compost · 10% aeration | General beds |
| Mel’s Mix | ⅓ compost · ⅓ coir/peat · ⅓ vermiculite | Square-foot gardening |
| Budget deep bed | bulky fill at the base, soil mix on top | Tall beds (hugelkultur) |
Multiply the bed area by the fill depth. A 1.2 m × 2.4 m bed filled 300 mm deep needs about 0.86 m³ (roughly 860 litres). At 150 mm deep it is half that, around 430 litres. Enter your exact bed size and depth above - and add a bed for each one you are filling.
A common, reliable mix is about 60% topsoil, 30% compost and 10% potting or aeration material (such as perlite or composted bark). The popular "Mel's Mix" uses equal thirds of compost, peat or coir, and vermiculite. Work out your total volume here, then split it by your chosen ratio to know how much of each to buy.
Most vegetables and flowers are happy in 250–300 mm of soil. Root crops like carrots and parsnips prefer 300 mm+. If the bed sits on open ground, roots can grow down further, so you can fill the upper portion with good soil. Set your fill depth in the calculator to match.
For tall beds, fill the bottom third with bulky low-cost material - logs, branches, leaves or coarse compost (a method called hugelkultur) - then top with your good soil mix. To use this, set the calculator depth to only the soil layer you are actually buying, not the full height of the bed.
It depends on bag size: a 1.2 m × 2.4 m bed filled 300 mm deep (about 860 litres) is roughly eighteen 50-litre bags. For more than about ten bags, buying topsoil and compost in bulk and mixing your own is usually much cheaper. The calculator gives the bag count for the size you pick.
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