Mulch Calculator
Find how much mulch you need for your beds, how many bags that is, and whether bags or a bulk delivery works out cheaper at your local prices.
How to measure garden beds for mulch
Measure the length and width of each bed. Long, narrow borders are easy: length times average width. For beds with curves, imagine them as a few rectangles, or measure the widest and narrowest points and use the average. Tree rings and round beds can use the circle option; enter the full diameter of the ring. If you have several beds, calculate each and add them up, or add the areas yourself and enter the total as the length with a width of 1.
Then choose a depth. Around 2 to 3 inches (5 to 7.5 cm) is a common depth for new beds. If you are topping up existing mulch, measure what is left and add only the difference. Mulch piled too deep can keep the soil too wet, and mulch heaped against tree trunks ("volcano mulching") can harm the bark, so keep a gap around stems and trunks.
The mulch formula
Cubic feet = length (ft) × width (ft) × depth (in) ÷ 12Cubic yards = cubic feet ÷ 27Bags = cubic feet ÷ bag size (cu ft), rounded upBagged mulch in the US is commonly sold in 2 cu ft and 3 cu ft bags; in the UK, Australia and much of Europe bags are labelled in litres, such as 50, 60 or 75 L. Bulk mulch is sold by the cubic yard or cubic metre. A few handy conversions:
- 1 cubic yard = 27 cubic feet = 13.5 bags of 2 cu ft = 9 bags of 3 cu ft.
- 1 cubic metre = 1,000 litres = 20 bags of 50 L.
- 1 cubic yard covers about 324 sq ft at 1 inch, 162 sq ft at 2 inches and 108 sq ft at 3 inches.
Worked example
A border along a fence is 40 ft long and 5 ft wide, mulched 3 inches deep.
- Area: 40 × 5 = 200 sq ft.
- Volume: 200 × (3 ÷ 12) = 50 cu ft, which is 50 ÷ 27 = 1.85 yd³.
- In 2 cu ft bags: 50 ÷ 2 = 25 bags.
- With the example prices of $4 a bag and $40 a yard in bulk (no delivery fee), bags cost $100 and bulk about $74.
Once a delivery fee is added, the answer can change. With a $30 fee the bulk total would be about $104, slightly more than the bags. That is why the calculator asks for the delivery fee and tells you which option is cheaper. A metric example: a 12 × 1.5 m border at 7.5 cm needs 1.35 m³, or 27 bags of 50 L.
Settling and extra
Fresh organic mulch is fluffy and settles after watering and rain, and it breaks down over the season. Many gardeners buy 5% to 10% extra, or round bulk orders up to the next half or whole yard. Bagged mulch is often slightly compressed, so an opened bag can spread a little further than its label suggests, but it is safer to plan on the stated volume.
Bags or bulk: estimating cost
The calculator compares two ways of buying:
- Bags: bag count × price per bag. Convenient for small jobs, easy to transport, and tidy to store, but usually more expensive per cubic yard.
- Bulk: cubic yards (or cubic metres) × bulk price, plus delivery. Usually cheaper per yard for larger jobs, but you need somewhere for the pile and a way to move it, and delivery may have a minimum.
The default prices are examples only. Enter what your garden centre or landscape yard charges. Prices differ by mulch type, from shredded hardwood and bark to dyed mulch and pine straw. If you are pricing a long-lasting alternative, try the rubber mulch calculator.
Mulching tips
- Weed and water the bed before mulching; mulch helps suppress new weeds rather than removing existing ones.
- Keep mulch a few inches away from tree trunks, plant stems and house siding.
- Use edging to keep mulch out of the lawn and paths.
- For a tree ring, a wider, shallower ring is generally better than a deep, narrow pile.
Frequently asked questions
How many bags of mulch are in a yard?
One cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cu ft (buy 14) or 9 bags of 3 cu ft. In metric, one cubic metre is 1,000 litres, or 20 bags of 50 L.
How much area does a yard of mulch cover?
One cubic yard covers about 324 sq ft at 1 inch deep, 162 sq ft at 2 inches and 108 sq ft at 3 inches.
How deep should mulch be?
Around 2 to 3 inches is a common depth for planting beds. Keep mulch pulled back a few inches from tree trunks and plant stems so they can stay dry.
Is it cheaper to buy mulch in bags or bulk?
It depends on your local prices and the delivery fee. Small jobs are often cheaper in bags, while larger jobs are often cheaper in bulk once the delivery fee is spread over several yards. Enter both prices and the fee, and the calculator shows which option is cheaper.
Why does my mulch look thinner after a few weeks?
Organic mulch settles and breaks down over time, so beds usually need a top-up. Adding an extra 5% to 10% when you buy can help with initial settling.