Mulch Calculator: Cubic Yards & Bags Needed
Work out how many cubic yards or bags of mulch you need for rectangular beds, round beds and tree rings, and compare bulk delivery with bags.
To cover 100 square feet with 3 inches of mulch you need about 0.93 cubic yards, or 13 bags of 2 cu ft. One cubic yard covers 108 square feet at 3 inches deep. Formula: area × depth (inches ÷ 12) ÷ 27 = cubic yards.
Your numbers
Result
How much mulch do I need?
Mulch is sold by the cubic yard in bulk and by the cubic foot in bags. Multiply the bed's area by the depth you want, then convert to the unit you are buying.
cubic yards = cubic feet ÷ 27
2 cu ft bags = cubic feet ÷ 2
For a round bed or tree ring, area = π × (outer radius² − trunk radius²). A 6-foot ring around a 1-foot trunk at 3 inches deep takes about 6.9 cubic feet — 4 bags.
Worked example: three beds and a tree ring
A front yard has a 20 × 4 ft border (80 sq ft), a 10 × 6 ft bed (60 sq ft) and a 5 ft ring around a tree with a 6-inch trunk (π × (2.5² − 0.25²) ≈ 19.4 sq ft). The total is about 159 sq ft. At 3 inches deep that is 159 × 0.25 = 39.9 cubic feet, or 1.48 cubic yards: 20 bags of 2 cu ft, or one bulk delivery. At $38 a yard that's about $56 in bulk, against about $90 for 20 bags at $4.50 — if you can accept a delivery fee under the savings.
Mulch needed by area
| Bed area | 2 in deep | 3 in deep | 4 in deep |
|---|---|---|---|
| 50 sq ft | 0.31 yd³ | 0.46 yd³ | 0.62 yd³ |
| 100 sq ft | 0.62 yd³ | 0.93 yd³ | 1.23 yd³ |
| 250 sq ft | 1.54 yd³ | 2.31 yd³ | 3.09 yd³ |
| 500 sq ft | 3.09 yd³ | 4.63 yd³ | 6.17 yd³ |
| 1.000 sq ft | 6.17 yd³ | 9.26 yd³ | 12.35 yd³ |
| 2.000 sq ft | 12.35 yd³ | 18.52 yd³ | 24.69 yd³ |
Mulch coverage chart
| Depth | 1 cubic yard covers | One 2 cu ft bag covers |
|---|---|---|
| 1 in | 324 sq ft | 24 sq ft |
| 2 in | 162 sq ft | 12 sq ft |
| 3 in | 108 sq ft | 8 sq ft |
| 4 in | 81 sq ft | 6 sq ft |
How deep should mulch be?
Two to three inches suits most flower beds and shrub borders: enough to suppress weeds and hold moisture without smothering roots. Around trees, keep mulch a few inches away from the trunk — piling it against the bark (a "mulch volcano") invites rot and pests. For playground surfaces use 6–12 inches of engineered wood fiber or rubber mulch to meet safety guidelines.
Which type of mulch?
| Type | Best for | Notes |
|---|---|---|
| Hardwood bark | General beds | Breaks down in 1–2 years, improves soil |
| Cedar / cypress | Beds near the house | Naturally resists insects, lasts longer |
| Pine straw | Acid-loving plants | Light, easy to spread |
| Dyed mulch | Curb appeal | Color fades in about a year |
| Rubber | Playgrounds | Doesn't decompose; costly |
How to spread mulch well
- Edge the bed and pull weeds first; a thin layer of cardboard under mulch smothers persistent weeds.
- Spread it evenly at the target depth. Keep it 2–3 inches away from stems and several inches from tree trunks.
- Water after spreading to settle it, and refresh with a thin top-up each spring rather than piling on a new thick layer.
Bulk or bagged?
One cubic yard equals 13.5 two-cubic-foot bags. At typical prices bulk mulch is cheaper once you need about 2 cubic yards or more, but it requires delivery and somewhere to dump the pile. Bags are easier to carry and store for small beds.
Frequently asked questions
How many 2 cu ft bags of mulch are in a cubic yard?
A cubic yard contains 27 cubic feet, which is 13.5 bags of 2 cu ft mulch.
How much area does one yard of mulch cover?
About 108 square feet at 3 inches deep, 162 square feet at 2 inches, or 81 square feet at 4 inches.
How much mulch do I need for a 10×10 bed?
A 10 × 10 ft bed (100 sq ft) at 3 inches deep needs 25 cubic feet — about 0.93 cubic yards or 13 bags of 2 cu ft.
How deep should mulch be around trees?
Two to four inches, spread in a wide ring, and pulled back a few inches from the trunk.
How often should I replace mulch?
Top up with an inch or two each spring or every other year. Rake the old layer first so the total depth doesn't exceed 3–4 inches.
Can mulch be too thick?
Yes. More than 4 inches can block water and oxygen and encourage fungus and rodents. Keep it 2–3 inches deep around plants.
Is mulch cheaper by the bag or in bulk?
Bulk is usually cheaper per cubic foot once you need around 2 yards or more. Compare delivery fees — they can erase the savings on small orders.
How do I measure an irregular bed?
Break it into rectangles and circles, calculate each, and add the results, or use the square footage calculator.
Sources and further reading
- Mulching trees and shrubs — University of Maryland Extension
- Mulching landscape trees — Penn State Extension
- Too much of a good thing: mulch volcanoes slowly kill trees — University of Illinois Extension
- NIST Special Publication 811: conversion factors — National Institute of Standards and Technology
These references support the general guidance on this page. The calculator applies the standard formulas shown above to the numbers you enter.
Related calculators
. Estimates only. Always confirm quantities with your supplier or a qualified contractor before ordering, and add extra for waste and site conditions.