Mulch Calculator
Enter the size of your bed and get the number of whole bags of mulch for each bag size, with the working shown. A bed that is not a rectangle can be drawn with Draw a shape.
Estimates for planning, not professional advice. Read the full notice.
The drawing did not open. Length and width are still here.
Bed: shape and size
Skip the drawingDrag a round corner to move it. The small hollow diamond on a side is its curve handle: drag it across the side to curve the side (it is not a corner). To add a corner (a new point), tap the side itself, then choose Add a point here. Tapping a corner or a side opens its actions. Drag empty space to move the view; pinch, or Ctrl and the mouse wheel, to zoom. The keys are listed under Keys.
Keys
- Tab
- next corner; each says how far it is from corner 1
- Arrow keys on a corner
- move it one square; ten with Shift; 1/16 in with Alt
- Delete or Backspace
- remove the corner; its two sides join in one straight side
- + on a corner
- add a corner halfway along the next side
- Arrow keys on the drawing
- move the view; farther with Shift
- + and - on the drawing
- zoom in and out
- 0 on the drawing
- show the whole shape
- Ctrl+Z (Cmd+Z on a Mac)
- undo, except inside a typed field (it keeps its own)
- Ctrl+Shift+Z or Ctrl+Y
- redo
- Escape while dragging
- put it back where it was
- Enter on a corner or side
- go to its actions
- Escape in the actions
- close them and go back to the drawing
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- Area
- 120 ft²
- Perimeter
- 44 ft
- Cut-out edges
No area until the shape is fixed.
Estimate for planning, from what you entered and the product data shown. Check product labels and your supplier before you buy.
Shape: Rectangle Change
Sides
Corners
Cut-outs
Feet and inches, like 12' 6"
Example: a mulch bed
15 2 ft³ bags
- In 0.5 ft³ bags 60 × 0.5 ft³ bags
- In 0.75 ft³ bags 40 × 0.75 ft³ bags
- In 1 ft³ bags 30 × 1 ft³ bags
- In 1.5 ft³ bags 20 × 1.5 ft³ bags
- In 3 ft³ bags 10 × 3 ft³ bags
Your project
Enter a size to see your total.
Each product is rounded up once for the whole project, so the total can be less than the items bought alone added together. A line counted from a cut layout (sheets, boards or tiles laid out piece by piece) is counted for each item and added.
Shopping list
| Item | Size | Buy |
|---|---|---|
| Mulch in bags | 2 ft³ bag | 15 |
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Saved projects
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Worked example: a mulch bed
Show the working
- Bed area 12 ft × 10 ft = 120 ft²
- Mulch volume at the depth 120 ft² × 3 in = 30 ft³
- Add the waste allowance, once 30 ft³ + 0 % waste = 30 ft³
- Divide by the bag size 30 ft³ ÷ 2 ft³ = 15 bags
- Round up once, to whole bags 15 bags = 15 bags
Assumptions
The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.
| Assumption | Value | Details and changes |
|---|---|---|
| Mulch depth | 3 in[1] | |
| Default Iowa State Extension: 3 to 4 in around trees and shrubs, 2 to 3 in on heavy soils. Other extensions differ. | ||
| Mulch bag size | 2 ft³ | |
| Default Bag sizes are on the label. Check your label or supplier. | ||
| Landscape waste or overage | 0% | |
| Default No silent overage. Check your label or supplier. | ||
| Supplier's smallest yard step | 0.5 yd³ | |
| Default Suppliers sell bulk in steps. Check your label or supplier. | ||
| Weight of green wood chips (the source does not say loose or compacted) | 473 lb/yd³[2] | |
| EPA's volume-to-weight factors for wood chips: 473 lb per cubic yard green and 243 lb per cubic yard dry. The table does not say whether the yard is loose or compacted. | ||
| Weight of dry wood chips (the source does not say loose or compacted) | 243 lb/yd³[2] | |
| EPA's volume-to-weight factors for wood chips: 473 lb per cubic yard green and 243 lb per cubic yard dry. The table does not say whether the yard is loose or compacted. | ||
Feet and inches, like 12' 6"
Common jobs
Mulch in cubic yards and in bags of each size for common beds
| Bed (size × depth) | Cubic yards | Cubic yards at the step | 0.5 ft³ bags | 0.75 ft³ bags | 1 ft³ bags | 1.5 ft³ bags | 2 ft³ bags | 3 ft³ bags |
|---|---|---|---|---|---|---|---|---|
| 12 ft 6 in × 3 ft 4 in × 3 in | 0.39 yd³ | 0.5 yd³ | 21 | 14 | 11 | 7 | 6 | 4 |
| Round bed 8 ft across × 2 in | 0.31 yd³ | 0.5 yd³ | 17 | 12 | 9 | 6 | 5 | 3 |
| Tree ring 6 ft across, 12 in trunk × 3 in | 0.25 yd³ | 0.5 yd³ | 14 | 10 | 7 | 5 | 4 | 3 |
Each row is worked out on its own: the exact yards, the yards at the supplier's step in the assumptions above, and a whole number of bags of each size.
Topping up old mulch
Mulch to add over a layer already in the bed
| Bed (size, depth wanted, depth there) | Depth to add | Volume to add | Cubic yards | 2 ft³ bags |
|---|---|---|---|---|
| 12 ft × 10 ft, 3 in wanted, 1 in there | 2 in | 20 ft³ | 0.74 yd³ | 10 |
The depth to add is the depth you want minus the depth already there, and the volume is worked out for that difference only.
Depths from the sources
Mulch depths as three university extension services give them
| Source and case | Depth |
|---|---|
| Iowa State, trees and shrubs on well-drained sites: from | 3 in |
| Iowa State, trees and shrubs on well-drained sites: to | 4 in |
| Iowa State, heavy soils: from | 2 in |
| Iowa State, heavy soils: to | 3 in |
| Clemson, fine wood and bark mulches, no deeper than: low end | 2 in |
| Clemson, fine wood and bark mulches, no deeper than: high end | 3 in |
| Clemson, coarse mulches, as deep as | 4 in |
| Maryland, wood chips: from | 1 in |
| Maryland, wood chips: to | 3 in |
| Maryland, gap to keep at a tree trunk | 3 in |
The calculator starts from the Iowa State depth for trees and shrubs. The sources differ, so each depth is listed with its own wording.
Questions
Should I buy mulch in bags or in bulk?
The calculator shows whole bags of each size for the same bed. Bulk is sold by the cubic yard and your supplier sets the step it is ordered in. Prices, delivery charges and what fits your site are yours to weigh, so this page gives no price.
How do I add new mulch over old mulch?
Work out the depth to add yourself, as the depth you want minus the depth of the old layer, and enter that as the depth. The calculator works out the volume and the bags for the depth you enter, and the topping-up table on this page shows one bed worked that way.
How deep should mulch be?
Iowa State Extension gives a depth for trees and shrubs on well-drained sites and a shallower one for heavy soils. Clemson Extension limits fine mulches and allows coarse mulches to go deeper, and the University of Maryland Extension gives its own range and a gap to keep at the trunk. The depths table lists each one, and the calculator starts from the Iowa State depth.
How much does a yard of mulch weigh?
The calculator does not give a weight; it gives whole bags for the size of your bed. The weight of a yard depends on the kind of mulch and how wet it is, so ask your supplier for the weight of your product.
Sources (4)
-
How deep should the mulch layer be around trees and shrubs? (Yard and Garden FAQ) (opens in new tab), Iowa State University Extension and Outreach, last updated March 3, 2022.
Code or government.
“A 3- to 4-inch-layer of wood chips or shredded bark would be appropriate for well-drained sites around trees and shrubs. On heavy soils, a 2- to 3-inch-layer would be suitable.”
Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 1) -
Volume-to-Weight Conversion Factors (opens in new tab), U.S. Environmental Protection Agency, Office of Resource Conservation and Recovery, April 2016; table on PDF p. 5.
Code or government.
“Wood Chips, green cubic yard 473 ... Wood Chips, dry cubic yard 243”
Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 2) -
Mulch (HGIC 1604) (opens in new tab), Clemson Cooperative Extension, Home & Garden Information Center, revised June 20, 2016.
Code or government.
“Many wood and bark mulches are composed of fine particles and should not be more than 2 to 3 inches deep. ... Coarse-textured mulches such as pine bark nuggets ... can be as deep as 4 inches. ... One cubic yard will cover a 324-square-foot area with an inch of mulch.”
Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 3) -
Mulching Trees and Shrubs (opens in new tab), University of Maryland Extension, updated December 6, 2023.
Code or government.
“Always keep mulch shallow, from one to three inches. Keep mulch about 3 inches away from the base of tree trunks. ... Apply wood chips 1-3 inches deep and sawdust 1 inch deep.”
Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 4)
These are summaries of what the sources say, not professional advice. Codes and product data change. Check with your building department and the product label about your own project.
Sources
- [1] Iowa State University Extension and Outreach, How deep should the mulch layer be around trees and shrubs? (Yard and Garden FAQ). Checked November 12, 2026. https://yardandgarden.extension.iastate.edu/faq/how-deep-should-mulch-layer-be-around-trees-and-shrubs
- [2] U.S. Environmental Protection Agency, Office of Resource Conservation and Recovery, Volume-to-Weight Conversion Factors. Checked November 12, 2026. https://www.epa.gov/sites/default/files/2016-04/documents/volume_to_weight_conversion_factors_memorandum_04192016_508fnl.pdf
- [3] Clemson Cooperative Extension, Home & Garden Information Center, Mulch (HGIC 1604). Checked November 12, 2026. https://hgic.clemson.edu/factsheet/mulch/
- [4] University of Maryland Extension, Mulching Trees and Shrubs. Checked November 12, 2026. https://extension.umd.edu/resource/mulching-trees-and-shrubs