Yards and tons for gravel beds, paths and driveways.
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Mulch Calculator
Yard & gardenQuick answer: mulch is depth times area — and depth is where most people go wrong. This calculator turns your bed size and chosen depth into cubic yards and bag counts, with bag-vs-bulk costs side by side. A 10×10 ft bed at 3 inches deep needs 0.93 cubic yards — 13 bags of standard 2 cu ft mulch.
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Cubic yards
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Bags (2 cu ft)
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Bags (1.5 cu ft)
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Bags (3 cu ft)
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Est. cost in bags
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Est. cost in bulk
Bulk mulch is usually far cheaper per yard once you pass about 2 yards — but you need somewhere for the pile to land. Bag counts are rounded up to whole bags.
How it works — the formula
For a rectangular bed:
Volume (ft³) = Length (ft) × Width (ft) × Depth (in) ÷ 12For a round bed:
Volume (ft³) = π × (Diameter (ft) ÷ 2)² × Depth (in) ÷ 12 Cubic yards = ft³ ÷ 27 · Bags = ⌈ ft³ ÷ bag size (ft³) ⌉| Depth | Coverage per cubic yard | Coverage per 2 cu ft bag | Best for |
|---|---|---|---|
| 2 in | 162 ft² | 12 ft² | Refreshing existing beds |
| 3 in | 108 ft² | 8 ft² | Standard weed suppression |
| 4 in | 81 ft² | 6 ft² | New beds, heavy weed pressure |
Three inches is the depth most extension services recommend: enough to block light from weed seeds without smothering plant roots. Deeper is not better around tree trunks — keep mulch pulled back from bark.
Worked examples
| Bed | Volume | Cubic yards | 2 cu ft bags |
|---|---|---|---|
| 10 × 10 ft, 3 in deep | 25.0 ft³ | 0.93 yd³ | 13 |
| 20 × 5 ft, 2 in deep, 10% extra | 18.3 ft³ | 0.68 yd³ | 10 |
| Round bed, 10 ft diameter, 2 in deep | 13.1 ft³ | 0.48 yd³ | 7 |
Check the first row: 10 × 10 × (3 ÷ 12) = 25 ft³. Divide by 27 → 0.93 yd³. Divide 25 by the 2 ft³ in a standard bag → 12.5, rounded up to 13 bags.
Frequently asked questions
How many bags of mulch are in a cubic yard?
13.5 × 2 cu ft bags, 18 × 1.5 cu ft bags, or 9 × 3 cu ft bags — 27 ft³ either way. Per project, fractions round up.
How deep should mulch be?
2–3 in to refresh, 3–4 in for a new bed. More than 4 in wastes money and can smother roots.
Is bulk mulch cheaper than bags?
Usually much cheaper per yard ($30–$50 bulk vs $55–$70 bagged), plus delivery. Bags win for small or hard-to-reach beds.
How much area does one bag of mulch cover?
A 2 cu ft bag covers ≈12 ft² at 2 in, 8 ft² at 3 in, or 6 ft² at 4 in deep.
Should I remove old mulch first?
Usually no — rake it loose and top up to depth. Remove only matted, sour-smelling layers.
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See the full list on the Home & DIY Calculators page.
Estimates only. Bag sizes and bulk densities vary by product and supplier; confirm the bag volume printed on the bag and your supplier's yard measure before ordering.