Mulch bag coverage guide (how many bags do you need?)
How to plan bagged mulch: bag sizes, how depth changes coverage, and why settling matters.
Bag size is the first check
Bagged mulch is sold by volume (often 2 cu ft or 3 cu ft). Convert your bed volume to cubic feet, then divide by bag size and round up.
Bag size consistency
Bag volumes vary by brand. Use the volume on the bag (cu ft or liters) and do not assume all bags are the same size.
- Mixing bag sizes can skew totals; track each size separately.
- Round up to full bags; partial bags are not sold.
Quick coverage chart (bags per 100 sq ft)
A quick way to plan bags is to convert depth to feet and use: bags = (area × depth in feet) ÷ bag cubic feet, then round up.
| Depth | 2 cu ft bags | 3 cu ft bags |
|---|---|---|
| 1" (0.083 ft) | ≈ 5 bags | ≈ 3–4 bags |
| 2" (0.167 ft) | ≈ 9 bags | ≈ 6 bags |
| 3" (0.25 ft) | ≈ 13 bags | ≈ 9 bags |
2 cu ft vs 3 cu ft bags (what changes)
The math is the same—only the bag volume changes. The practical difference is handling and rounding: you often end up buying one extra bag because you can’t buy partial bags.
- 3 cu ft bags reduce total bag count, but each bag is heavier to carry and spread.
- If color matching matters, buy enough in one batch; mixing lots can look uneven.
Depth selection (1 vs 2 vs 3 inches)
| Depth | Common use | Reminder |
|---|---|---|
| 1" | Top-up/refresh | May not suppress weeds by itself |
| 2" | Most beds (general) | A common balance of coverage and cost |
| 3"+ | Deeper mulch look / erosion control (project dependent) | Avoid piling against trunks; watch drainage near foundations |
Worked example
Example: 300 sq ft bed at 2 inches needs volume = 300 × (2/12) = 50 cu ft. If you use 2 cu ft bags: 50/2 = 25 bags (then add a small buffer for uneven edges).
Settling and top-ups
- Fresh mulch often settles after watering or rain.
- A light buffer prevents thin spots after the first week.
Bulk vs bags (when to switch)
Bagged mulch is convenient for small projects. For larger beds, bulk delivery is often cheaper per cubic foot and saves carrying time. The tradeoff is delivery access and the need to move material from a pile.
- Compare total cubic feet: 1 cubic yard = 27 cubic feet (bags add up fast).
- Plan space for delivery and tarps/wheelbarrow paths to protect lawns and driveways.
- Confirm mulch type and moisture—coverage claims vary by product.
How to measure beds (fast method)
- Break the bed into rectangles/triangles and add areas together.
- For curved edges, measure an average width and multiply by length as a planning estimate.
- Use multiple depth checks if the bed isn’t uniform (edges are often thinner).
Bags vs cubic yards (delivery comparison)
If you are comparing bag totals to bulk delivery, convert to cubic yards: cubic yards = cubic feet ÷ 27. Example: 54 cu ft is 2 cu yd. This makes price comparisons much easier.
- Bag coverage claims vary by brand; volume math is more reliable.
- Plan edging and cleanup: mulch migrates without a defined border.
- Avoid “mulch volcano” around trunks; keep mulch away from bark.
Planning notes
- Mulch settles after spreading and watering. A small buffer helps.
- If color matching matters, buy enough at once.
- Avoid piling mulch against trunks (keep it away from bark).