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Mulch Calculator

Area 1

Sample shape, not to scale.

No result yet. Enter length, width and depth.

Buying options

Starts at 0%. We found no authoritative figure for how much extra mulch to buy, so none is added. Enter your own percentage if you want a margin.

Bag size

Optional. The volume printed on your bag, in cubic feet. When entered, it is used instead of the sizes above.

Embed this calculator

Paste this code into your page. The calculator works inside the frame, with a link back to this page under it.

How to calculate mulch

Mulch is bought by volume, so the sum is the area of the bed times the depth of the layer.

Start with the area of each bed in square feet. Then multiply by the depth in feet, which is the depth in inches divided by 12. A 3 in layer is 0.25 ft. The answer is in cubic feet.

Bulk mulch is delivered by the cubic yard, so divide the cubic feet by 27. The calculator rounds that up to the next hundredth of a yard. Bags are sold by the cubic foot, so divide by the bag volume and round up to a whole bag.

Clemson Extension gives a shortcut that reaches the same place: square feet × depth in inches ÷ 324 = cubic yards. It works because one cubic yard, spread an inch deep, covers 324 sq ft.

Examples

Front bed: 20 ft × 4 ft × 3 in

  1. Area: 20 ft × 4 ft = 80 sq ft = 7.43 m²
  2. Volume: 80 sq ft × 3 in = 20.0 cu ft = 0.74 cu yd
  3. With 0% waste: 20.0 cu ft + 0% = 20.0 cu ft = 0.74 cu yd
  4. Bulk order: 20.0 cu ft ÷ 27, rounded up to 0.01 cu yd = 0.75 cu yd
  5. Bags: 20.0 cu ft ÷ 2.00 cu ft per bag, rounded up = 10
  6. Cost: 10 bags × $3.97 = $39.70

10 2 cu ft bags no waste added. Bulk order: 0.75 cu yd. Estimated cost: $39.70.

Round bed: 6 ft × 3 in

  1. Area: π × (6 ft ÷ 2)² = 28.3 sq ft = 2.63 m²
  2. Volume: π × (6 ft ÷ 2)² × 3 in = 7.1 cu ft = 0.26 cu yd
  3. With 0% waste: 7.1 cu ft + 0% = 7.1 cu ft = 0.26 cu yd
  4. Bulk order: 7.1 cu ft ÷ 27, rounded up to 0.01 cu yd = 0.27 cu yd
  5. Bags: 7.1 cu ft ÷ 2.00 cu ft per bag, rounded up = 4

4 2 cu ft bags no waste added. Bulk order: 0.27 cu yd.

Three beds in one trip: Area 1: 20 ft × 4 ft × 3 in; Area 2: 6 ft × 3 in; Area 3: 8 ft × 6 ft × 3 in

  1. Area 1: 20 ft × 4 ft = 80 sq ft = 7.43 m²
  2. Area 1 volume: 80 sq ft × 3 in = 20.0 cu ft = 0.74 cu yd
  3. Area 2: π × (6 ft ÷ 2)² = 28.3 sq ft = 2.63 m²
  4. Area 2 volume: π × (6 ft ÷ 2)² × 3 in = 7.1 cu ft = 0.26 cu yd
  5. Area 3: 8 ft × 6 ft ÷ 2 = 24 sq ft = 2.23 m²
  6. Area 3 volume: 24 sq ft × 3 in = 6.0 cu ft = 0.22 cu yd
  7. Total volume: 20.0 cu ft + 7.1 cu ft + 6.0 cu ft = 33.1 cu ft = 1.22 cu yd
  8. With 0% waste: 33.1 cu ft + 0% = 33.1 cu ft = 1.22 cu yd
  9. Bulk order: 33.1 cu ft ÷ 27, rounded up to 0.01 cu yd = 1.23 cu yd
  10. Bags: 33.1 cu ft ÷ 2.00 cu ft per bag, rounded up = 17

17 2 cu ft bags no waste added. Bulk order: 1.23 cu yd.

Ring around a tree: Outer diameter 6 ft, inner diameter 1 ft, depth 3 in

  1. Area: π × ((6 ft ÷ 2)² − (1 ft ÷ 2)²) = 27.5 sq ft = 2.55 m²
  2. Volume: 27.5 sq ft × 3 in = 6.9 cu ft = 0.25 cu yd
  3. With 0% waste: 6.9 cu ft + 0% = 6.9 cu ft = 0.25 cu yd
  4. Bulk order: 6.9 cu ft ÷ 27, rounded up to 0.01 cu yd = 0.26 cu yd
  5. Bags: 6.9 cu ft ÷ 2.00 cu ft per bag, rounded up = 4

4 2 cu ft bags no waste added. Bulk order: 0.26 cu yd.

Mulch by bed size and depth

Shape and sizeVolume1.5 cu ft2 cu ft3 cu ft
Rectangle: 10 ft × 10 ft × 2 in0.62 cu yd1296
Rectangle: 10 ft × 10 ft × 3 in0.93 cu yd17139
Rectangle: 10 ft × 10 ft × 4 in1.24 cu yd231712
Rectangle: 20 ft × 10 ft × 3 in1.86 cu yd342517
Rectangle: 18 ft × 18 ft × 1 in1.00 cu yd18149
Triangle: 12 ft × 8 ft × 3 in0.45 cu yd864

Bags needed for each bag size, no waste added. The volume includes the waste.

Recommended mulch depth

Questions

How deep should I spread mulch?

University extension services agree on 2 to 4 in for organic mulch around trees and shrubs, and on not going past 4 in. Fine mulches sit at the low end, 2 to 3 in, and coarse bark nuggets at 3 to 4 in. The list above this section names who says what.

How many bags of mulch make a cubic yard?

A cubic yard is 27 cu ft, so it takes 13.5 bags of 2 cu ft. Bags come whole, which makes it 14.

My bags are a size that isn't listed. Can I still use this?

Yes. The 1.5, 2 and 3 cu ft sizes are offered because each is sold as such by at least two stores we checked. For any other bag, type the cubic feet printed on it into "Your own bag size" and the count uses that instead.

Why does the calculator add no extra?

Because we found no authoritative figure for it. Mulch settles and beds are never perfectly even, but no extension service or manufacturer we read puts a percentage on that. The waste field starts at 0 and is there for your own allowance.

Is bulk mulch or bagged mulch the better buy?

The sources behind this site give no cut-off, so compare the two prices. The "Buy as" switch under Buying options flips the result between bags and bulk. Each side keeps its own price, per bag or per cubic yard, so you can enter both and switch back and forth. Delivery is not included.

How much area does one bag cover?

A 2 cu ft bag covers 24 sq ft at 1 in deep. Divide 24 by your depth in inches. That is 12 sq ft at 2 in and 8 sq ft at 3 in.

My bed is a ring, a trapezoid or an odd shape. Which shape do I pick?

Ring is for a bed around a tree trunk or a round feature. Enter the outer and inner diameters, each measured straight across through the centre. Trapezoid is for a bed with two parallel sides. Enter both sides and the distance between them, measured at a right angle. If you already know the area in square feet, choose Known area and type it in with the depth. Any other outline can be split into pieces, each added with "Add another area".

Related tools

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Sources

The volume of a bed is plain geometry, area × depth. Clemson Extension publishes the same sum as a rule of thumb, square feet × inches ÷ 324 = cubic yards. Each bag size offered is stated on at least two product pages (1.5 cu ft by Scotts, Do it Best and True Value; 2 cu ft by Scotts and Patuxent Nursery; 3 cu ft by two garden centres). Each depth recommendation comes from at least two university extension services. No source gives an allowance for waste or settling.

Methodology and sources

Last reviewed: October 8, 2026