Plot No. 65 · Home & Garden
Mulch Calculator
Work out how much mulch a bed needs. It multiplies bed length by width by the spread depth to get the volume in cubic metres, then converts that to litres, to standard 50 litre bags, and to cubic yards so you can order in whatever unit your supplier uses.
Bag counts are rounded up to whole bags. A spread depth of 5 to 8 cm suits most ornamental beds.
The link saves your inputs so you can bookmark or share this exact result.
How the mulch quantity is worked out
The calculator multiplies the bed length by width by the spread depth to get the volume in cubic metres, with the depth converted from centimetres to metres. That single volume is then shown four ways so it matches whatever unit your supplier quotes.
Cubic metres are multiplied by 1,000 to give litres, divided by 50 and rounded up for bagged mulch, and multiplied by 1.30795 to give cubic yards for loose deliveries. Showing all four lets you compare bagged against bulk pricing at a glance.
How to use the mulch calculator
- Enter the bed length and width in metres.
- Set the spread depth in centimetres, with 5 to 8 cm suiting most ornamental beds.
- Compare the litres, 50 litre bags and cubic yards to decide whether bagged or loose mulch is cheaper.
Worked examples
Long border bed
Inputs: 5 m by 1.5 m bed, 7 cm deep
Result: 0.525 cubic metres, which is 525 litres, eleven 50 litre bags, or about 0.69 cubic yards loose.
Deeper weed-suppressing layer
Inputs: Same bed mulched 10 cm deep
Result: 0.75 cubic metres, 750 litres, fifteen bags or about 0.98 cubic yards, close to the point where loose delivery wins on price.
Limitations and common mistakes
Edge cases and limitations
- Bags are rounded up to whole 50 litre sacks, so the litres figure is the more precise number for loose orders.
- Bagged volumes are nominal and settle in the bag, so a 50 litre bag may spread slightly less than 50 litres.
- It assumes an even depth across a rectangular bed. Mound mulch around shrubs by eye rather than relying on the average.
Common mistakes
- Spreading mulch too deep against stems, which traps damp and can rot the plant rather than help it.
- Ordering by bag for a large bed when loose mulch by the cubic yard would have been far cheaper per litre.
Frequently asked questions
How much mulch do I need?
Multiply area by depth. A 5 m by 1.5 m bed mulched 7 cm deep is 0.525 cubic metres, which is 525 litres or eleven 50 litre bags. In cubic yards that is about 0.69.
How deep should mulch be?
Around 5 to 8 cm suppresses weeds and holds moisture without smothering roots. Going much deeper wastes material and can starve the soil of air, so 7 cm is a sensible default for most ornamental beds.
Should I order in bags or loose by the cubic yard?
Bags suit small beds and are easy to carry. Once you need more than about 1 cubic metre, loose mulch by the cubic yard is usually cheaper per litre, which is why this tool shows both bags and cubic yards.
Related calculators
Paint Calculator
Work out litres of paint and 2.5 litre tins from room size, coats and coverage.
Tile Calculator
Find how many tiles to buy from the area and tile size, including a waste allowance.
Concrete Calculator
Estimate concrete volume and 25 kg bags for a slab, with a 10 percent waste buffer.
Raised Bed Soil Calculator
Work out the soil to fill a raised bed in cubic metres, litres and 50 litre bags.
See all home & garden calculators.