Mulch Bag Calculator
How many bags of mulch your beds need at 2, 3 or 4 inches, and what one bag covers.
Quick estimating rule of thumb
For mulch bags: area (sq ft) × depth (in) ÷ 12 = cubic feet, then divide by the bag size. A cubic yard is 13.5 bags of 2 cubic feet, 18 bags of 1.5, or 27 bags of 1. One 2 cubic foot bag covers about 12 sq ft at 2 inches. Past roughly ten bags, bulk delivered is usually cheaper.
This mulch bag calculator turns your bed size and the depth you want into a straight bag count, so you know what to load before you get to the garden centre. The default is the standard 2 cubic foot bag; 1.5, 1 and 0.75 cubic foot bags are all one tap away.
Switch to Bags I have to work the other way: enter the bags already in the boot and it tells you how much bed they will actually cover at your chosen depth.
For bulk yardage, delivery and depth guidance, see the mulch calculator. Playground rubber is denser and priced differently, so use the rubber mulch calculator.
What one bag of mulch covers
A standard 2 cubic foot bag covers 12 square feet at 2 inches deep, 8 square feet at 3 inches, and 6 square feet at 4 inches. Those three numbers cover most of what people need: 2 inches for an annual top-up, 3 inches for a proper weed-suppressing layer, 4 inches around shrubs and trees where you want to smother growth.
Put differently, a 2 cubic foot bag spread 3 inches deep covers a patch a little under 3 feet square. A 10 ft × 4 ft border at 3 inches takes 5 bags. A wraparound foundation bed of 300 square feet at 3 inches takes about 38.
Bags per cubic yard, and when bulk wins
It takes 13.5 bags of 2 cubic feet to make one cubic yard, 18 bags of 1.5 cubic feet, or 27 bags of 1 cubic foot. Landscape yards quote in cubic yards, so that conversion is what lets you compare the two prices honestly. The bags per cubic yard page has the same figure for every material and bag size.
Bulk usually pulls ahead somewhere between 8 and 10 bags, often sooner once delivery is spread across a larger order. Bulk also spares you a boot full of plastic. Against that, you need somewhere to dump the pile, a wheelbarrow, and the willingness to move it all in one weekend. Under about 15 bags, most people are better off with bags.
Topping up rather than starting fresh
Beds that were mulched last year rarely need a full layer. Wood mulch breaks down roughly an inch a year, so measure what is left and add only the difference. Rake the old surface first to break any matted crust. A hard cap sheds water rather than letting it through, which does the plants no favours.
Because a top-up is often just one inch, the bag count halves or better against a fresh bed. Set the depth to 1 inch in the calculator and a 2 cubic foot bag covers 24 square feet.
Frequently asked questions
How many bags of mulch do I need?
Multiply the bed area in square feet by the depth in inches, then divide by 24 for 2 cubic foot bags. A 100 square foot bed at 3 inches needs about 13 bags.
How many bags of mulch are in a cubic yard?
13.5 bags of 2 cubic feet, 18 bags of 1.5 cubic feet, or 27 bags of 1 cubic foot. A cubic yard is 27 cubic feet.
How much does a 2 cubic foot bag of mulch cover?
12 square feet at 2 inches deep, 8 square feet at 3 inches, and 6 square feet at 4 inches.
How many bags of mulch for a 200 square foot bed?
About 17 bags of 2 cubic feet at 2 inches deep, or about 25 bags at 3 inches.
Is it cheaper to buy mulch in bags or bulk?
Bulk is usually cheaper once you need more than about 8 to 10 bags, and cheaper still on larger orders where delivery is spread further. Below that, bags win on convenience and there is no delivery fee.
How deep should mulch be?
Two to three inches for most beds, three to four around shrubs and trees for weed control. Keep it pulled back a few inches from trunks and stems. Piled against bark it traps moisture and invites rot.
How much does a bag of mulch weigh?
A 2 cubic foot bag of dry wood mulch weighs about 20 lb, but a bag that has sat out in the rain can be 40 lb or more. Wet bags are also harder to spread evenly.
How many bags of mulch fit in a car?
A sedan boot holds about 6 to 8 bags, an SUV with seats down about 15 to 20, and a pickup bed 30 or more. Past that it is usually a second trip or a bulk delivery.
How many bags of mulch are on a pallet?
Typically 60 to 65 bags of 2 cubic feet, which is roughly 4.5 cubic yards. Many garden centres discount by the pallet.
Do I need to remove old mulch before adding new?
Usually not. Rake it to break up any crust, then top up by the difference to reach your finished depth. Remove it only if it is compacted, mouldy, or harbouring pests.
How much mulch do I need to top up an existing bed?
Usually one inch, since wood mulch breaks down about that much a year. At 1 inch, a 2 cubic foot bag covers 24 square feet, half the bags of a fresh layer.
How many bags of mulch for a tree ring?
A 4-foot-diameter ring is about 12.5 square feet, so roughly 2 bags at 3 inches. A 6-foot ring is about 28 square feet, or 4 bags. Keep mulch off the trunk itself.
Should I buy extra bags of mulch?
Add about 10%. Beds are rarely the neat rectangles you measured, edges lose material, and running one bag short across a whole border is a frustrating second trip.