How much mulch do I need?
One cubic yard of mulch covers about 108 square feet at 3 inches deep, 162 square feet at 2 inches, or 81 square feet at 4 inches. That single number does most of the work.
In bags: a 2 cubic foot bag covers roughly 8 square feet at 3 inches deep. There are 13.5 of those bags in a cubic yard.
Worked example: a bed 20 ft × 4 ft is 80 square feet. At 3 inches deep that is 80 × 0.25 = 20 cubic feet, which is 0.74 cubic yards or 10 bags.
How the calculation works
Cubic feet = bed area (sq ft) × depth (in) ÷ 12. Cubic yards = cubic feet ÷ 27. Bags = cubic feet ÷ bag size, rounded up.
For curved or irregular beds, break the shape into rectangles and add them, or measure the average width across several points and multiply by length. Mulch is forgiving — a 10% error is invisible.
The calculator does not subtract space for existing plants. Established shrubs displace less mulch than people expect, and the extra gives you the ring depth you want around each plant.
Typical mulch cost, mid-2026
| Material | Unit | Typical range |
|---|---|---|
| Hardwood / bark mulch (bulk) | per yd³ | $30.00 – $50.00 |
| Dyed mulch — black, brown, red (bulk) | per yd³ | $35.00 – $55.00 |
| Cedar / cypress (bulk) | per yd³ | $40.00 – $70.00 |
| Bagged mulch | per 2 cu ft bag | $3.50 – $5.50 |
| DeliveryFlat fee — same for 1 yard or 10 | per trip | $50.00 – $150 |
| Spreading labourIf you are hiring it out | per yd³ | $25.00 – $50.00 |
Bulk becomes cheaper than bagged at roughly 1 cubic yard once delivery is included, and dramatically cheaper above 3 yards.
What goes wrong on this job
- Three inches is the target. Two inches lets weeds through; five inches suffocates roots and creates a hydrophobic crust that sheds water instead of absorbing it.
- Never pile mulch against trunks or stems. The "mulch volcano" traps moisture against bark, invites rot and girdling roots, and is the single most common landscaping mistake.
- Buy mulch by volume, never by weight. Wet mulch can weigh twice as much as dry mulch for the same coverage, so a per-ton price tells you nothing useful.
- Refreshing an existing bed? Measure only the depth you are adding. Most beds only need an inch or so to look new again, which cuts the order by two-thirds.
Frequently asked questions
How many bags of mulch are in a cubic yard?
13.5 bags at the standard 2 cubic foot size, 18 bags if they are 1.5 cubic feet, or 9 bags at 3 cubic feet.
How much area does a yard of mulch cover?
About 108 square feet at 3 inches deep. At 2 inches it stretches to 162 square feet; at 4 inches it only covers 81.
Is bulk mulch cheaper than bags?
Above about one cubic yard, yes — usually by 30–50% even after the delivery fee. Below a yard the flat delivery charge wipes out the saving and bags win.
How deep should mulch be?
Three inches for most beds. Go to 4 inches only for aggressive weed pressure in open beds with no shallow-rooted plants, and stay at 2 inches around annuals and perennials.
How often should mulch be replaced?
Top it up annually with an inch or so. A full replacement every 3–4 years is enough unless the mulch has matted into a water-shedding crust, in which case break it up before adding more.