ConstructionCalc

Mulch Calculator: Bags, Yards & Coverage

How much mulch you need in bags and cubic yards for your beds at the depth you choose, with a top-up mode so you only buy the difference.

By Marko VisicBSc Physics, University of Ljubljana

2.00yd³

cubic yards (yd³) of mulch at 3 in over 216 sq ft

or 27 bags of 2 ft³

1 yd³3 ft3 ft3 ft
Cubic meters
1.529 m³
Cubic feet
54 ft³
One bag covers
8 sq ft

Weight (EPA wood chips, dry to green): 18–35 lb per bag, 243–473 lb per yard.

Bed 1

You need 2.00 yd³, or 27 bags

An 18 by 12 ft bed at 3 inches deep needs 2.00 cubic yards, or 27 two-cubic-foot bags. Most beds already hold some mulch, so switch on top-up mode and the tool buys only enough to bring them back to 2 to 3 inches, not a full fresh layer.

Mulch is sold both ways, so this gives bags and bulk yards together. For the soil underneath, the topsoil calculator handles beds the same way, and the cubic yard calculator does any bulk material by volume.

Estimate only: bag sizes vary by brand, so confirm the printed cubic feet. Weights use the EPA wood-chip density; bark and dyed products differ.

How deep to spread mulch

For garden beds, 2 to 3 inches is the sweet spot: enough to hold moisture and block weeds, not so deep it smothers roots. Replenish as needed to keep 2 to 3 inches. Keep mulch 12 to 18 inches back from tree trunks and 1 to 2 inches off shrub stems, and never pile it against a trunk. Volcano mulching rots bark and invites pests. Pine straw is sold in bales, and rubber mulch goes deeper under play equipment, so each has its own calculator: the pine straw calculator and the rubber mulch calculator.

Mulch depth and the gaps around trunks and stems2–3 in layer12–18 in from trunk1–2 in off shrubs
Keep mulch off trunks and stems, with no volcano mulching.

How much mulch is in a cubic yard

A cubic yard is 27 cubic feet, so the bag count depends only on the bag’s printed volume. These are common example sizes, so check your bag.

Two cubic feet is a common bag size (the Scotts example); your bag may differ.
Bag size (ft³)Bags per cubic yard
1.518
213.5
2.510.8
39

Topping up an existing bed

Most beds already carry mulch from last year, so a full fresh layer over-buys. UF/IFAS says to replenish to keep 2 to 3 inches, not to re-mulch from bare soil. Enter the depth already there and the tool subtracts it, buying only the difference, never a negative amount if the bed is already deep enough.

Worked example and scenarios

Three beds at once, then a quick lookup for common bed sizes at two depths, in two-cubic-foot bags.

A 20 × 6 ft border, a 10 × 8 ft bed and a 6 ft tree ring, all 3 in deep: 120 + 80 + 28 = 228 sq ft × 0.25 ft = 57 ft³ ÷ 27 = 2.11 cubic yards, or 29 bags.

Two-cubic-foot bags, no top-up. Round up, since you cannot buy part of a bag.
Bed area (sq ft)Bags at 2 inBags at 3 in
5057
100913
2001725
5004263

What mulch weighs

Wood-chip mulch is light compared with soil or stone. The EPA puts wood chips at 243 lb per cubic yard dry and 473 lb green, so a two-cubic-foot bag runs about 18 lb to 35 lb. Bark and dyed-hardwood mulches have no single published weight, so treat these wood-chip figures as the guide and weigh a bag if it matters.

Mulch calculator FAQ

How much mulch do I need?

Measure each bed’s area, pick a depth (2 to 3 inches for garden beds), and the tool returns cubic yards and bags. For a top-up, enter the mulch already there and it buys only the difference.

How many bags of mulch are in a cubic yard?

A cubic yard is 27 cubic feet, so it is 13.5 of the common two-cubic-foot bags, 9 three-cubic-foot bags, or 18 of the smaller 1.5-cubic-foot bags. Check your bag’s printed volume.

How deep should mulch be?

Keep garden beds at 2 to 3 inches and replenish to hold that depth. Deeper smothers roots; shallower lets weeds through. Keep it 12 to 18 inches off trunks and 1 to 2 inches off shrub stems.

How much does a bag of mulch weigh?

A two-cubic-foot bag of wood chips weighs about 18 lb dry and up to 35 lb green. The EPA puts wood chips at 243 to 473 lb per cubic yard. Bark and dyed mulches vary; weigh one if it matters.

How many quarts are in a 2-cubic-foot bag?

A two-cubic-foot bag holds 3,456 cubic inches. A US dry quart is 67.2006 cubic inches, so that bag works out to about 51 dry quarts, or 60 liquid quarts in the smaller liquid quart. Bagged soil and mulch are sold by dry measure, so read a bag labeled in quarts as dry quarts.

Sources

  1. University of Florida IFAS Extension — Florida-Friendly Landscaping Program. Principle 4 Guidance: Mulch. page as retrieved Nov 2026
  2. The Scotts Miracle-Gro Company. Scotts Nature Scapes Color Enhanced Mulch, 2 cu. ft. — product page. page as retrieved Nov 2026
  3. U.S. Environmental Protection Agency (EPA), Office of Resource Conservation and Recovery. Volume-to-Weight Conversion Factors (April 2016). Apr 2016
  4. National Institute of Standards and Technology (NIST). NIST Handbook 44 (2026), Appendix C. General Tables of Units of Measurement. 2026 edition