Mulch Calculator

How to use this mulch calculator

1. Choose the shape that matches your bed: rectangle, circle, triangle, trapezoid, or a circle border for a ring around a tree. Curved or irregular beds are easiest if you split them into simple shapes, calculate each and add the results.
2. Enter the measurements and pick a unit (feet, inches, yards, meters or centimeters).
3. Set the depth. Use the quick buttons for common depths of 1, 2, 3, 4 and 6 inches.
4. Add the size of the bags you plan to buy and, if you like, the price to see how many bags and what it will cost.

How much mulch do I need?

Volume is area times depth. A 10 ft × 10 ft bed at 3 inches deep is 100 square feet × 0.25 ft = 25 cubic feet. Divide by 27 to get 0.93 cubic yards, or divide by the bag size: 13 bags of 2 cubic feet.

How much mulch do I need for 100 square feet?

Depth	Sq ft per cubic yard	Sq ft per 2 cu ft bag	Bags (2 cu ft) per 100 sq ft	Cubic yards per 100 sq ft
1 in	324	24	5	0.31
2 in	162	12	9	0.62
3 in	108	8	13	0.93
4 in	81	6	17	1.23
6 in	54	4	25	1.85

For example, 100 square feet at 2 inches deep needs 16.7 cubic feet: 9 bags, or 0.62 cubic yards.

How many bags of mulch are in a cubic yard?

Bag size	Bags per cubic yard
1 cubic foot	27
1.5 cubic feet	18
2 cubic feet	13.5
3 cubic feet	9

How deep should mulch be?

A layer of about 2 to 3 inches is a common target for most beds. Fine or shredded mulch can be thinner, while coarse bark is often used at 3 to 4 inches. Too little lets weeds through and dries out quickly. Too much can hold water against stems and keep air from roots. When topping up an existing bed, a 1 inch refresh is often enough.

Types of mulch

• Shredded hardwood or bark: knits together, stays put on slopes and breaks down slowly into the soil.
• Wood chips: coarse, often inexpensive and good for paths and around trees.
• Pine needles or straw: light and easy to spread, but they break down or blow away faster.
• Cedar and cypress: popular for their look and scent, usually priced above basic bark.
• Rubber mulch: long-lasting and often used for play areas, but it does not feed the soil.
• Gravel or stone: permanent and good for drainage, but heavier and warmer. You can use the gravel calculator for these.

Bulk or bagged mulch?

Bags are easy to carry and good for small jobs. For larger beds, compare the total cost. A 2 cubic foot bag price times 13.5 gives the cost of a cubic yard in bags. Compare that with the bulk price per yard plus any delivery fee.

Before you buy

Mulch settles and breaks down, so a little extra in the first year is rarely wasted. Check the bag size before you divide, because 1.5, 2 and 3 cubic foot bags all sit on the same shelf. On a slope, a shredded mulch holds better than large bark nuggets. Around trees, keep the mulch a few inches back from the trunk: the circle border shape counts only the ring, so you do not pay for the part you leave clear. Measure the bed itself, not the whole garden.