Coverage by depth
| Depth | One cubic yard covers | Bags per 100 sq ft | When to use it |
|---|---|---|---|
| 1" | 324 sq ft | 4.2 bags | Topping up an established bed |
| 1.5" | 216 sq ft | 6.3 bags | Light refresh |
| 2" | 162 sq ft | 8.3 bags | Minimum for any weed suppression |
| 2.5" | 130 sq ft | 10.4 bags | Around shallow-rooted perennials |
| 3"common | 108 sq ft | 12.5 bags | The standard target for most beds |
| 3.5" | 93 sq ft | 14.6 bags | Heavier weed pressure |
| 4" | 81 sq ft | 16.7 bags | Maximum for planted beds |
| 5" | 65 sq ft | 20.8 bags | Open beds and pathways only |
| 6" | 54 sq ft | 25.0 bags | Playground and pathway depth |
Bag figures assume the standard 2 cubic foot bag. Divide by 0.75 for 1.5 cu ft bags, or multiply by 0.667 for 3 cu ft bags.
Bags per cubic yard
| Bag size | Bags per cubic yard | Coverage per bag at 3" |
|---|---|---|
| 1.5 cu ft | 18 bags | 6 sq ft |
| 2 cu ft (most common)common | 13.5 bags | 8 sq ft |
| 3 cu ft | 9 bags | 12 sq ft |
When bulk beats bagged
The crossover sits at about one cubic yard. Below that, the flat delivery fee — usually $50–150 per trip regardless of quantity — cancels out the lower per-yard price.
Above one yard, bulk wins clearly. A cubic yard of mulch is 13.5 two-cubic-foot bags. At $4 a bag that is $54 in bags against $30–55 delivered in bulk, and the gap widens with every additional yard because delivery stays flat.
There is a handling cost too. Thirteen bags is thirteen trips from the car, thirteen bags to cut open and thirteen empty plastic bags to dispose of. One bulk pile is one wheelbarrow route.
Getting the depth right
- Three inches is the target for almost every planted bed. It blocks light to weed seeds while still letting water and air through to the root zone.
- Two inches is the floor. Below that, weeds find the light and you will be doing the job again by midsummer.
- Four inches is the ceiling around plants. Deeper mulch stays saturated, starves roots of oxygen, and forms a hydrophobic crust that sheds water instead of absorbing it.
- Never pile mulch against trunks or stems at any depth. The "mulch volcano" traps moisture against bark and causes rot and girdling roots — it is the most common and most expensive landscaping mistake.
- Refreshing rather than replacing? Measure only the depth you are adding. Most beds look new again with a single inch, which cuts the order by two-thirds.
Frequently asked questions
How many square feet does a yard of mulch cover?
108 square feet at 3 inches deep. At 2 inches it stretches to 162 square feet, and at 4 inches it only covers 81.
How many bags of mulch are in a cubic yard?
13.5 bags at the standard 2 cubic foot size, 18 bags at 1.5 cubic feet, or 9 bags at 3 cubic feet.
How much mulch do I need for a 100 square foot bed?
About 0.93 cubic yards at 3 inches deep, which is roughly 12.5 standard bags. At 2 inches you need 0.62 yards or about 8 bags.
How deep should mulch be to stop weeds?
Three inches. Two is the absolute minimum and lets persistent weeds through; going past four inches starts damaging the plants you are mulching around.