Step by step
- Measure. Get the length and width of the bed in feet. For a circle, measure the radius. Split odd shapes into rectangles and add them up.
- Calculate the area. Length x width gives square feet.
- Choose a depth. Two to three inches is typical. Divide by 12 to get feet.
- Get cubic feet. Area x depth in feet.
- Convert. Divide cubic feet by 27 for cubic yards, or by the bag size for bags.
- Add 10% and round up. Mulch settles, so a small buffer saves a second trip.
Tools for measuring and spreading
Spreading mulch goes faster with the right kit.
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Worked example
A 10 ft by 10 ft bed at 3 in deep is 100 sq ft. Depth in feet is 3 / 12 = 0.25, so the volume is 100 x 0.25 = 25 cubic feet. Adding 10% for settling gives 27.5 cubic feet, which is 1.02 cubic yards (27.5 / 27). In 2 cu ft bags that is 14 bags (27.5 / 2 = 13.75, rounded up).
Buy it by the bag
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Buy it delivered in bulk
For bigger jobs, Bulk mulch is sold by the cubic yard and delivered loose. Local landscape suppliers usually quote a delivery fee, so ask for the total before you order.
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Frequently asked questions
- What is the formula for mulch?
- Area in square feet x depth in feet = cubic feet. Divide by 27 for cubic yards.
- Do I add extra for waste?
- Adding 10% is a common allowance for settling and uneven ground.