Mulch calculator
Spreading bark, wood chips, straw or compost? Enter the area you want to cover and how thick you want the layer — GrowGuide returns the mulch to buy in cubic feet, cubic yards, litres and bags.
Area to cover
Mulch needed
One cubic yard spreads about 100 ft² at 3 inches deep, or 160 ft² at 2 inches.
How to measure for mulch
Outline the area
Measure the bed as a rectangle, a circle, or type in a total area you already know. Odd shapes? Break them into simple rectangles and add the results.
Choose a depth
Two to three inches is the sweet spot for most gardens — enough to lock in moisture and block weeds without smothering roots. Go a little deeper on bare, weedy ground.
Get the count
See the volume in every common unit plus the number of bags for the size you buy, so you can weigh bagged against a bulk load in seconds.
Why mulch depth is worth getting right
Too thin does nothing
A dusting under an inch lets light through and weeds punch straight past it. The moisture and weed-suppressing benefits really begin at around two inches.
Too thick suffocates
Pile mulch much beyond four inches, or heap it against stems, and you trap damp air, starve roots of oxygen and invite rot. Depth control protects the plants you are trying to help.
Buy once
An accurate estimate means a single delivery or trolley load. No half-covered bed, no bags hardening in the shed until next spring.
Working out how much mulch to buy
Mulch is sold by volume but spread by area, which is where people trip up. The volume you need is simply the area of the bed multiplied by how deep you want the layer. A thin two-inch layer over a big area can still add up to more than a cubic yard, so it always pays to run the numbers before loading the car.
What depth for what job?
For ornamental beds and around established shrubs, two to three inches (5–8 cm) is ideal. To knock back persistent weeds on open ground, go to three or four inches. Around trees, keep the same depth but pull the mulch back a few centimetres from the trunk — a volcano of mulch piled against bark traps moisture and causes rot.
Bags or bulk?
Bagged mulch is convenient for a bed or two and typically comes in 2-cubic-foot bags, or roughly 50–70 litres. Once you are covering a large area the maths turns quickly: a single cubic yard equals thirteen and a half of those 2-cubic-foot bags, so bulk delivery usually costs far less per litre and saves a stack of plastic.
Coverage rule of thumb
A cubic yard of mulch covers about 100 square feet at three inches deep, 160 square feet at two inches, or 325 square feet as a light one-inch topping. If you prefer metric, a cubic metre covers roughly 20 square metres at 5 cm. This calculator does the exact figure for your bed, but those rules are handy for a quick gut check.
Frequently asked questions
How much mulch do I need?
Multiply the area you are covering by the depth of the layer. This calculator does it for you and shows the total in cubic feet, cubic yards, cubic metres, litres and the number of bags for the size you buy.
How deep should mulch be?
Two to three inches (5–8 cm) suits most beds. Increase to three or four inches to suppress stubborn weeds, and keep it clear of plant stems and tree trunks to avoid rot.
How many bags are in a cubic yard?
A cubic yard is 27 cubic feet, so it equals thirteen and a half standard 2-cubic-foot bags. Above roughly a cubic yard, bulk delivery is usually cheaper.
My bed is an odd shape — what do I do?
Split it into simple rectangles or circles, calculate each part, and add the volumes. Alternatively, estimate the total area and use the total-area option directly.
Does the type of mulch change the amount?
No — volume depends only on area and depth. Bark, wood chips, straw and compost fill the same space. They differ in how fast they break down and how often you top up, not in the volume for a given depth.
Is anything uploaded or stored?
No. The tool runs entirely in your browser, with no account and no server, and it keeps working offline once the page has loaded.