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Last updated: 3 October 2026
Bark mulch calculator
Work out mulch to cover your beds and borders. UK units: metres, centimetres and litres. Results update as you type.
How to use this calculator
Measure the length and width of the area in metres, then decide how deep you want the bark mulch in centimetres. For odd shapes, split the area into rectangles and add them up using the number of areas box.
A typical depth is 5–8 cm on beds, kept clear of stems. These are common guidelines, not rules. Follow the advice for your project or product.
How it's calculated
Volume = length × width × depth. Depth is converted to metres (cm ÷ 100). Weight uses a typical density of 0.35 tonnes per cubic metre. Real products vary with moisture and type, so treat weight as a guide.
Worked example
An area 4 m long and 1.5 m wide, filled 7 cm deep: 4 × 1.5 × 0.07 = 0.42 m³, about 0.15 tonnes at a typical 0.35 t/m³. That's 6 bags of 70 litres, or about 5 loads in an 85 litre barrow.
Common questions
Should I order extra?
Adding around 10% is sensible. Loose material settles and compacts once it's spread and watered, and uneven ground uses more than a flat measurement suggests.
How many bags are in a bulk bag?
It depends on the bulk bag. A 0.7 m³ bulk bag holds 700 litres, which is the same as 10 bags of 70 litres. Bulk bag sizes vary between suppliers, so check the listing.
How much does bark mulch weigh?
We use a typical 0.35 tonnes per cubic metre. Wet material can weigh noticeably more. If weight matters for delivery or a trailer, ask your supplier for their figure.