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Mulch Calculator

Use this mulch calculator to find how many cubic yards or bags of mulch a bed takes, and how many square feet one yard covers at the depth you choose.

  • Instant answer as you type
  • Nothing you type is sent anywhere
  • Worked example with clear steps

Your measurements

ft
ft
in
Clemson Extension says fine mulches should not be more than 2 to 3 inches deep, and coarse ones can be as deep as 4. 3 is an example value, not a recommendation. The limit of 48 is ours.
%
We found no source for an extra on mulch, so it starts at 0. The limits are ours.
Bag size and price (optional)

Your bag's size is printed on it, and bags differ. The price is yours: we state none, and we store and show no prices.

ft³
$ per bag

Result

Calculated live
Mulch to order 16 ft³, 0% extra
0.59 yd³
Bags to order of 2 ft³ each
8 bags
Volume as measured 0.59 yd³
16 ft³
Area 3 in deep
64 ft²
One cubic yard covers at 3 in deep
108 ft²

Based on NIST SP 811 Clemson Extension Full list of sources

Assumptions and constants

You can change

Fixed values (exact definitions and references)

These are exact definitions and cannot be edited.

Cubic feet in a cubic yard Reference [1]

27 ft³ per yd³

3 ft × 3 ft × 3 ft.

Inches in a foot Reference [1]

12 in per ft

The foot is 0.3048 m and the inch is 0.0254 m, both exact, so 12 inches make a foot.

How to use the mulch calculator

  1. Pick Rectangle, Circle or Triangle, then enter the bed's size in feet.
  2. Enter the Depth you want, in inches.
  3. Check Extra to order. Open Bag size and price (optional) and enter the Size of one bag.
  4. Read Mulch to order and Bags to order.
  5. Use Copy result or Print, and confirm the amount with your supplier.

How many cubic yards of mulch do I need?

Volume in cubic feet = area in square feet x depth in inches / 12. A cubic yard is 27 cubic feet, so cubic yards = cubic feet / 27. [1]

Clemson Extension says one cubic yard will cover a 324-square-foot area with an inch of mulch. [2] That agrees with the arithmetic: 27 x 12 = 324.

The formula

Put the two together: cubic yards = area in square feet x depth in inches / 324.

We found no source for an extra on mulch, so Extra to order starts at 0. Ask your supplier how much to add for settling and uneven spreading.

Worked example

A bed 4 ft wide and 16 ft long is 4 x 16 = 64 square feet. At 3 in deep, 64 x 3 / 12 = 16.00 cubic feet, and 16.00 / 27 = 0.59 cubic yards. With bags of 2 cubic feet, 16.00 / 2 = 8 bags.

Mulch bed: length 16 ft, width 4 ft A mulch bed seen from above, a long narrow rectangle four times as long as it is wide. Its length, 16 ft, is marked under it and its width, 4 ft, along the right side. From above Length 16 ft Width 4 ft
Drawn to scale for a bed 16 ft long and 4 ft wide. The depth, 3 in, goes into the page. The calculator turns the area and the depth into cubic yards and bags.

How many square feet does a yard of mulch cover?

One cubic yard covers 324 / depth in inches square feet. Per square foot, mulch 3 in deep is 3 / 12 = 0.25 cubic feet. The depths are examples to show the sum, not recommendations.

Coverage of one cubic yard, by depth
Depth (in) Square feet one yard covers Cubic feet per 100 ft²
1 3248.33
2 16216.67
3 10825.00
4 8133.33

How many bags of mulch are in a yard?

A yard is 27 cubic feet, so the bags in a yard = 27 / the size of one bag, rounded up. Bag sizes differ, so read the size on your bag. The sizes below are examples.

Bags in one cubic yard, by size of bag
Bag size (ft³) Bags before rounding Bags
1 2727
1.5 1818
2 13.514
3 99

How many bags of mulch do I need?

Bags = the cubic feet to order / the size of one bag, rounded up. For the example, 16.00 / 2 = 8 bags. Enter your bag's size under Size of one bag, in the section Bag size and price (optional) above.

How deep should mulch be?

Clemson Extension says many wood and bark mulches are composed of fine particles and should not be more than 2 to 3 inches deep, and that coarse-textured mulches such as pine bark nuggets can be as deep as 4 inches. [2]

We found no source that says whether 2 inches is enough for your bed. Ask your local extension service, and enter the depth you choose under Depth.

How much does mulch cost?

We state no price. Ask local suppliers for the price of one bag, then enter it under Price per bag, in the section Bag size and price (optional) above, to see the total for the bags to order. The site does not store the prices you type.

Common mistakes and limits

  • Mixing units. Enter the length and width in feet and the depth in inches.
  • Counting bags as yards. A yard is 27 cubic feet, so bags of 2 cubic feet take 13.5 bags to make a yard, which is 14 when rounded up.
  • Piling mulch against stems. Clemson Extension says to keep mulch 2 to 3 inches away from the stems of woody plants. [2]
  • What this tool does not cover: delivery, landscape fabric, edging and the weight of the mulch.

Frequently asked questions

How much mulch should I add to existing beds?

Enter the depth you want to add, not the total depth. For the example bed, adding 1 in takes 64 x 1 / 12 = 5.33 cubic feet, or 0.20 cubic yards. We found no source for how much to add.

What does 20 cubic yards of mulch look like?

20 cubic yards is 20 x 27 = 540 cubic feet, for example a pile 10 ft by 10 ft by 5.4 ft. Spread 3 in deep, it covers 20 x 108 = 2,160 square feet.

How close should mulch be to a plant?

Clemson Extension says to keep mulch 2 to 3 inches away from the stems of woody plants, and not to pile mulch against a trunk. [2]

Does rubber mulch or bark mulch change the amount?

We found no source that gives a different coverage for rubber or bark mulch. This calculator counts the volume you spread, so the same volume covers the same area at the same depth. Ask your supplier for the volume of a bag or a load.

Sources and references

  1. National Institute of Standards and Technology (NIST). NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically (SP 811, accessed November 2026). Used for: the inch and foot relationship and the 27 cubic feet in a cubic yard.
  2. Clemson Cooperative Extension, Home and Garden Information Center. Mulch, HGIC 1604 (Revised June 2016, accessed November 2026). Used for: the 324 square feet one cubic yard covers at 1 inch, and the depth advice.

How we use sources: methodology.

Estimates only. Confirm quantities with your supplier. See the disclaimer. Found a wrong result? Report an error.