Quick lookup
Mulch needed for common bed sizes (3 inches deep)
Most garden beds use a 3 inch layer of mulch. Bags are 2 cubic feet, cubic yards are 27 cubic feet. Cost estimate assumes $4 per bag or $35 per yard for hardwood mulch.
| Bed size | Sq ft | Cu yards | Cu feet | 2 cu ft bags | Est. cost |
|---|---|---|---|---|---|
| 4 × 8 ft (small bed) | 32 | 0.3 | 8 | 4 bags | $16 |
| 6 × 10 ft | 60 | 0.6 | 15 | 8 bags | $32 |
| 10 × 10 ft | 100 | 0.9 | 25 | 13 bags | $52 |
| 10 × 20 ft (foundation strip) | 200 | 1.9 | 50 | 25 bags | $100 |
| 12 × 15 ft | 180 | 1.7 | 45 | 23 bags | $92 |
| 15 × 20 ft (large garden) | 300 | 2.8 | 75 | 38 bags | $98 (yards) |
| 20 × 30 ft (whole yard) | 600 | 5.6 | 150 | 75 bags | $195 (yards) |
| 8 ft diameter tree ring | 50 | 0.5 | 13 | 7 bags | $28 |
Switch to bulk delivery once you pass roughly 1.5 cubic yards (40-50 bags) — bagged mulch costs twice as much per cubic foot at that scale.
Quick answer
How much mulch do I need?
Mulch is sold by volume: cubic yards (loose, in truck loads) or cubic feet (in bags, usually 2 cu ft). To know how much to buy, multiply your bed's area by the mulch depth you want, then convert to whichever unit your supplier uses. A 3 inch deep layer is the standard recommendation for most garden beds — deep enough to suppress weeds and retain moisture, shallow enough not to smother plants.
Our mulch calculator handles rectangular and circular beds, switches between imperial and metric, and shows you cubic yards, cubic feet, standard 2 cubic foot bag count, and a cost estimate. Use the numbers at the garden center or call your local landscape supply.
The math
The formula explained
Step 1: Calculate area
Rectangle: length × width. Circle: π × radius². For an L-shaped bed, split it into two rectangles, calculate each, and add them together.
Step 2: Convert depth to feet
Mulch depth is usually given in inches but the area is in square feet. Divide depth by 12. So 3 inches becomes 3 / 12 = 0.25 ft.
Step 3: Multiply for cubic feet
volume = area × depth. A 10 ft × 4 ft bed at 3 in deep is 10 × 4 × 0.25 = 10 cu ft. That is 5 bags of 2 cu ft mulch.
Step 4: Convert to cubic yards (if buying loose)
Divide cubic feet by 27. The same 10 cu ft is 10 / 27 = 0.37 cu yd. Most suppliers will not deliver less than a full cubic yard, so order 1 cubic yard if buying in bulk.
Decision guide
Bag vs bulk: which way to buy?
| Bagged (2 cu ft) | Bulk (cu yd) | |
|---|---|---|
| Cost per cu yd | $60–100 | $30–60 |
| Best for | Under 2 cu yd | 2 cu yd or more |
| Transport | Fits in any car | Needs a truck or delivery |
| Cleanup | Easy (just bags) | Driveway dust, tarp needed |
| Delivery fee | Free (pickup) or shipped | $50–100 |
| Selection | 10+ types and colors | Whatever your local yard has |
Math: 1 cu yd = 13.5 bags of 2 cu ft each. At Home Depot, that is about $70–80 in bags vs $40–60 from a bulk supplier. The break-even including delivery fees is typically 3 cubic yards.
Reference
How deep should mulch be?
- 2 inches — minimum for established beds with no weed pressure
- 3 inches — standard recommendation for most garden beds and trees
- 4 inches — new beds, weed-prone areas, or for moisture retention in dry climates
- 6 inches or more — avoid; can suffocate roots and create a 'mulch volcano' that rots tree bark
Do not 'volcano' trees
Use cases
Common bed sizes and mulch amounts
Small flower bed (3' × 8' × 3")
6 cu ft. 3 bags of 2 cu ft mulch.
Foundation bed (4' × 30' × 3")
30 cu ft = 1.1 cu yd. Bulk territory.
Around a tree (6' diameter × 3")
7.1 cu ft. 4 bags of 2 cu ft mulch.
Backyard playground (15' × 15' × 6")
112.5 cu ft = 4.2 cu yd. Always bulk.
Vegetable garden path (3' × 20' × 4")
20 cu ft = 0.74 cu yd. 10 bags or 1 cu yd loose.
Front yard refresh (20 trees, doughnut each)
Roughly 1.5 cu yd for refresh, 3 cu yd for new install.
Choose your material
Types of mulch compared
| Material | Lifespan + notes | |
|---|---|---|
| Hardwood (shredded bark) | Classic look | 1–2 years. Best all-purpose. |
| Cypress | Natural brown | 1–2 years. Bug-resistant. |
| Dyed mulch (red, black) | Vivid color | 1 year. Color fades; dye can leach. |
| Pine bark nuggets | Larger pieces | 2–3 years. Floats away in heavy rain. |
| Pine straw | Long, fine needles | 6–12 months. Common in the US South. |
| Cedar | Strong scent | 2–4 years. Natural pest repellent. |
| Rubber mulch | Tire chips | 10+ years. Heat-retaining. Not for plants. |
Common questions
How many bags of mulch in a cubic yard?
13.5 bags of 2 cubic foot mulch make one cubic yard. Some bags are 3 cubic feet — those are 9 per yard.
When should I apply mulch?
Late spring after the soil has warmed (mulching while soil is still cold keeps it cold longer). Refresh in early fall to insulate roots over winter.
Do I need to remove old mulch before adding new?
No, just rake the old mulch to break up any matted top layer and add 1–2 inches of new on top to refresh the color. Strip and replace entirely only every 3–4 years.
Will mulch hurt my plants?
Mulch helps almost every plant in a garden bed. Two situations where it can hurt: piled directly against stems or trunks (causes rot), or applied too thick (suffocates roots). Keep it under 4 inches and away from stems.
Is dyed mulch safe?
Most modern mulch dyes are iron oxide or carbon-based and considered safe. Older mulch (pre-2010 or no-name brands) sometimes used chromated copper arsenate-treated wood — avoid for vegetable gardens and play areas.
Related calculators
Mulch usually goes in with other landscape work. Here are the calculators most often used alongside it.
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Last reviewed: · Methodology based on US building code standards, contractor pricing surveys, and manufacturer specifications.