Mulch Calculator · Practical guide
How Much Mulch Do I Need for 100 Square Feet?
Exact mulch volumes for a 100 sq ft bed at every common depth — in yards and bags.
At a glance
The Quick Answer
For 100 square feet at the most common 3-inch depth, you need 25 cubic feet of mulch — that is about 0.93 cubic yards, or 13 standard 2-cubic-foot bags (rounded up). At 2 inches deep you need 9 bags; at 4 inches deep you need 17 bags.
Interactive tool
Mulch Calculator
Enter your own values, then compare the result with the examples below.
Mulch Estimate
Consider adding 5-10% extra to account for settling and uneven surfaces.
Mulch Needed per 100 Sq Ft by Depth
| Depth | Cubic Feet | Cubic Yards | Bags (2 cu ft) |
|---|---|---|---|
| 2 inches | 16.7 ft³ | 0.62 yd³ | 9 bags |
| 3 inches | 25.0 ft³ | 0.93 yd³ | 13 bags |
| 4 inches | 33.3 ft³ | 1.23 yd³ | 17 bags |
The Math Behind It
The calculator multiplies length × width × depth (converted from inches to feet). For 100 square feet at 3 inches: 100 × (3 ÷ 12) = 25 cubic feet. Divide by 27 to get cubic yards, or divide by 2 to get standard bag counts. For 200 square feet, simply double every figure — so a 3-inch layer needs 50 cubic feet, about 1.85 cubic yards, or 25 bags.
Bags or Bulk?
At under 1 cubic yard, 100 square feet of mulching is a comfortable bagged project — 13 bags fit in a couple of car trips. Once you pass 2 cubic yards (roughly 215 sq ft at 3 inches), bulk delivery usually works out cheaper per yard. Add 5–10% extra either way to cover settling and uneven ground.
Frequently Asked Questions
Is 2 inches of mulch enough for 100 square feet?
Two inches is enough to refresh an existing mulch layer, but for a new bed or bare soil, 3 inches gives better weed suppression and moisture retention for the same area.
How much does 100 square feet of mulch cost?
At roughly $4 per 2-cubic-foot bag, 13 bags run about $52. Bulk mulch at $30–$50 per cubic yard would be cheaper, but 0.93 yards is below most suppliers' minimum delivery quantity.
How many wheelbarrows is 100 square feet of mulch?
A standard wheelbarrow holds about 3 cubic feet, so the 25 cubic feet needed at 3 inches works out to roughly 8 to 9 wheelbarrow loads.
Do I need to remove old mulch before adding new?
No, as long as the total layer stays under 4 inches. Simply top up to the target depth — the old mulch keeps decomposing into the soil.