How Much Mulch Do You Need for 100 Square Feet?
100 square feet of mulch spread 3 inches deep needs 0.93 cubic yards, which is 13 bags of 2 cubic feet or 9 bags of 3 cubic feet. At 2 inches it is 0.62 yards and at 4 inches 1.23 yards.
Mulch for 100 square feet
Mulch is sold by the cubic yard in bulk and by the cubic foot in bags, so the answer depends on how deep you spread it. Multiply the bed area by the depth in feet to get cubic feet, then divide by 27 for yards.
cubic yards = cubic feet ÷ 27
At 3 inches deep: 100 × 0.25 = 25.0 cubic feet, which is 0.93 cubic yards. One cubic yard covers 108 square feet at 3 inches, so 100 ÷ 108 gives the same 0.93.
100 sq ft mulch chart
| Depth | Cubic feet | Cubic yards | 2 cu ft bags | 3 cu ft bags | Wheelbarrow loads |
|---|---|---|---|---|---|
| 2 in | 16.7 | 0.62 | 9 | 6 | 3 |
| 3 in | 25.0 | 0.93 | 13 | 9 | 5 |
| 4 in | 33.3 | 1.23 | 17 | 12 | 6 |
Bag counts are rounded up. A standard wheelbarrow holds roughly 6 cubic feet when heaped.
How deep should the mulch be?
Extension services generally recommend about 2 to 4 inches on beds: enough to suppress weeds and hold moisture, not so much that it smothers roots. Fine-textured mulch should stay toward 2 inches because it packs down, while coarse bark can go to 3 or 4. If last year's mulch is still there, measure what remains and only top up the difference.
Bulk or bags for 100 sq ft?
At 0.93 cubic yards this is a small job where bags are convenient: 13 two-cubic-foot bags. Compare the per-yard price once you pass about a yard, because bulk is usually cheaper. A pickup truck bed holds roughly 1 to 2 cubic yards of mulch depending on the sides, so bulk may need more than one trip.
Keep mulch off the trunk
Pull mulch back a few inches from tree trunks and the base of shrubs. Mulch piled against the bark holds moisture on it and can cause rot, the so-called mulch volcano.
For a different area or depth, use the mulch calculator; for odd-shaped beds, measure with the square footage calculator.
What 100 square feet looks like
A 100 sq ft bed is about a 10 × 10 ft square, or a 20 ft long border 5 ft wide: the size of a typical front-yard foundation bed or a small tree-and-shrub island.
Rough cost: bulk or bags
Using example prices of $38 per cubic yard for bulk and $4.50 per 2 cubic foot bag (check your local prices): bulk mulch for 0.93 yards is about $35 before delivery, and 13 bags is about $59. Bulk is cheaper even before you count the time spent carrying bags; add delivery for bulk, which is often $30 to $100 depending on distance.
Common mistakes
- Spreading mulch over weeds without removing or smothering them first.
- Piling it 6 inches deep, which can suffocate roots.
- Burying the trunk base or the crown of perennials.
- Ordering the exact amount: mulch settles and edges need extra.
Other sizes
How Much Mulch for 200 Square Feet · How Much Mulch for 500 Square Feet
Calculators for this guide
Frequently asked questions
How many bags of mulch for 100 square feet?
At 3 inches deep you need 13 bags of 2 cubic feet or 9 bags of 3 cubic feet.
How many yards of mulch for 100 sq ft?
0.62 cubic yards at 2 inches, 0.93 at 3 inches and 1.23 at 4 inches.
How much area does a cubic yard of mulch cover?
324 divided by the depth in inches: 162 sq ft at 2 inches, 108 at 3 inches and 81 at 4 inches.
How deep should mulch be?
About 2 to 4 inches on garden beds, kept a few inches clear of trunks.
Is bulk mulch cheaper than bags?
Usually, once you need around a cubic yard or more, though delivery fees and dump space matter.
Sources and further reading
- Mulching trees and shrubs — University of Maryland Extension
- Mulching landscape trees — Penn State Extension
- NIST Special Publication 811: conversion factors — National Institute of Standards and Technology
More guides
Estimates only. Always confirm quantities with your supplier or a qualified contractor before ordering, and add extra for waste and site conditions.