Free mulch bag calculator. Enter bed area and mulch depth to find the mulch volume in litres and the 50 litre bags you need for the bed.
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Enter bed area in square metres and mulch depth in centimetres. This mulch bag calculator multiplies area by depth to find the mulch volume in litres, then divides by 50 to find the 50 litre bags you need. A 10 square metre bed at 5 centimetres deep needs 500 litres, which is 10 bags. At 5 centimetres deep you need 50 litres per square metre.
Mulch litres equal bed area in square metres times depth in centimetres times 10. A 10 square metre bed at 5 centimetres deep needs 10 times 5 times 10, which is 500 litres, and 500 divided by 50 gives 10 bags of 50 litres. In feet, the same math is area in square feet times depth in inches divided by 12 for cubic feet, then divided by 27 for cubic yards.
Two to three inches, about 5 to 7.5 centimetres, suits most garden beds. Use about 2 inches for vegetable beds and fine mulch, 3 inches for flower beds, and up to 4 inches around trees and shrubs or for heavy weed suppression. Below 2 inches, weeds come through and the moisture benefit largely disappears. Above 4 inches, mulch can suffocate roots and hold too much moisture against stems.
One cubic yard holds 27 cubic feet. It covers about 324 square feet at 1 inch deep, 162 square feet at 2 inches, 108 square feet at 3 inches, and 81 square feet at 4 inches. In bags, one cubic yard equals about 13.5 bags of 2 cubic feet, 9 bags of 3 cubic feet, or 18 bags of 1.5 cubic feet. Always round bag counts up, because partial bags are not sold.
At 5 centimetres deep you need 50 litres of mulch per square metre. A standard 50 litre bag therefore covers 1 square metre at that depth, and a 100 litre bag covers 2 square metres. At 7.5 centimetres deep the figure rises to 75 litres per square metre, so a 10 square metre border needs 750 litres, or 15 bags of 50 litres. Use the calculator above with your exact area and depth for a precise figure.
Bags win on convenience for small beds and for storing leftovers. Bulk delivery by the cubic yard is usually cheaper per litre once you need about 1 to 2 cubic yards or more, even after a delivery fee. As a guide, bagged mulch often costs about twice as much per cubic foot as bulk. For one small bed, bags are simpler; for a whole garden border, price a bulk delivery before you buy dozens of bags.
Bark mulch suits most garden beds: it suppresses weeds, holds moisture, looks tidy, and lasts 2 to 3 years before a top up. Wood chip suits paths and larger areas and breaks down more slowly. Straw suits vegetable beds but breaks down fast. Decorative gravel is a permanent option for low maintenance gardens but adds no nutrients. Match the type to the bed, not just to the price.
Never pile mulch against a tree trunk. Keep a gap of about 15 centimetres, roughly 6 inches, between mulch and bark, and keep mulch a couple of inches away from plant stems and wooden siding. A mulch volcano traps moisture against bark, invites rot and pests, and can kill a young tree. Spread mulch in an even layer and leave the root flare visible.
For a circular area such as a tree ring, area is pi times radius squared, where radius is half the diameter. A 3 metre diameter circle has an area of about 7 square metres, so at 5 centimetres deep it needs about 350 litres, or 7 bags of 50 litres. For a ring, work out the outer circle, subtract the inner no mulch circle around the trunk, then multiply by depth.
Organic mulch settles and decomposes, losing roughly an inch a year, so a bed usually needs a top up of about 2 centimetres each spring rather than a full replacement. Add about 10 percent extra to your first order for settling and uneven ground, and rake the old layer before topping up so water can reach the soil. If you are between bag numbers, round up rather than down.
Divide your mulch litres by the bag size. A 10 square metre bed at 5 centimetres deep needs 500 litres, which is 10 bags of 50 litres.
Two to three inches suits most beds. Use 2 inches for vegetable beds, 3 inches for flower beds, and up to 4 inches around trees and shrubs.
One cubic yard equals 27 cubic feet: about 13.5 bags of 2 cubic feet, 9 bags of 3 cubic feet, or 18 bags of 1.5 cubic feet.
At 5 centimetres deep you need 50 litres per square metre. At 7.5 centimetres deep you need 75 litres per square metre.
Bags suit small beds and easy storage. Bulk delivery by the cubic yard is usually cheaper once you need about 1 to 2 cubic yards or more.
A mulch volcano is mulch piled against a tree trunk. It traps moisture against bark and invites rot and pests. Leave a 15 centimetre gap around the trunk.
Area is pi times radius squared. Multiply that area by depth for volume, then divide by bag size for bags. For a ring, subtract the inner circle first.
Yes. Add about 10 percent extra for settling and uneven ground, and plan a top up of about 2 centimetres each spring.
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