How to use this mulch calculator
- Choose the shape of your bed. Use Circle for rings around trees, and set How many? if you have several identical beds or tree rings.
- Enter the length and width (or diameter) and the depth of mulch you want. Each measurement has its own unit, so feet and inches or metres and centimetres both work.
- Optionally add a few percent extra for settling. Fresh, fluffy mulch settles after the first rain.
- Open Cost estimate to compare bagged mulch with a bulk delivery.
For odd-shaped beds, split them into rectangles, circles and triangles and run each one, or measure the total area with our square footage calculator and enter it as a rectangle with width 1. Filling a new or raised bed first? Use the topsoil calculator.
Mulch formula
Mulch is sold by volume, so you multiply the area of the bed by the depth. Convert the depth to the same unit as the area first.
Cubic feet = Square feet × (Depth in inches ÷ 12)
Cubic yards = Cubic feet ÷ 27
Litres = Square metres × Depth in cm × 10
Worked example: a 20 × 10 ft flower bed, 3 inches deep
- Area: 20 × 10 = 200 sq ft
- Depth: 3 in ÷ 12 = 0.25 ft
- Volume: 200 × 0.25 = 50 cu ft, which is 50 ÷ 27 = 1.85 yd³ (1.42 m³)
- Bags: 50 ÷ 2 = 25 bags of 2 cu ft, or 50 ÷ 3 = 16.7, so 17 bags of 3 cu ft
In metric: a 5 × 2 m border at 7.5 cm deep needs 10 m² × 0.075 m = 0.75 m³ (750 litres). That is15 bags of 50 L, 13 bags of 60 L or 10 bags of 80 L.
How much area mulch covers
| Depth | 1 cubic yard covers | 2 cu ft bag covers | 3 cu ft bag covers |
|---|---|---|---|
| 1 in | 324 sq ft | 24 sq ft | 36 sq ft |
| 2 in | 162 sq ft | 12 sq ft | 18 sq ft |
| 3 in | 108 sq ft | 8 sq ft | 12 sq ft |
| 4 in | 81 sq ft | 6 sq ft | 9 sq ft |
| Depth | 1 m³ covers | 50 L bag covers | 60 L bag covers | 80 L bag covers |
|---|---|---|---|---|
| 5 cm | 20 m² | 1.0 m² | 1.2 m² | 1.6 m² |
| 7.5 cm | 13.3 m² | 0.67 m² | 0.8 m² | 1.07 m² |
| 10 cm | 10 m² | 0.5 m² | 0.6 m² | 0.8 m² |
Recommended mulch depth
| Where | Typical depth |
|---|---|
| Flower beds and borders | 2–3 in (5–8 cm) |
| Around trees and shrubs | 2–3 in (5–8 cm), kept clear of the trunk |
| Vegetable beds (fine mulch or straw) | 1–3 in (2–8 cm) |
| Heavy weed suppression | 3–4 in (8–10 cm) |
| Wood-chip paths | 3–4 in (8–10 cm) |
| Topping up last year’s mulch | About 1 in (2–3 cm) |
These are common garden guidelines. Fine mulches can be applied a little thinner than coarse bark or wood chips.
Tips for mulching
- Weed and water first. Mulch holds in moisture, so lay it on damp, weed-free soil.
- Don’t build “mulch volcanoes”. Piling mulch against tree trunks keeps the bark wet and invites rot and pests. Leave a gap of a few inches around trunks and stems.
- Edge the bed. A clean edge stops mulch washing onto lawns and paths, so you lose less of it.
- Spread from piles. Tip bags or barrow loads in small piles across the bed, then rake level. It is much easier than spreading from one big heap.
- Check bag sizes. Bags are labelled in cubic feet in the US and in litres in the UK and Europe. One 2 cu ft bag holds about 57 litres.
Frequently asked questions
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cu ft mulch (buy 14) or 9 bags of 3 cu ft mulch.
How much area does a cubic yard of mulch cover?
One cubic yard covers about 324 sq ft at 1 inch deep, 162 sq ft at 2 inches, 108 sq ft at 3 inches and 81 sq ft at 4 inches.
How much does a 2 cubic foot bag of mulch cover?
A 2 cu ft bag covers about 12 sq ft at 2 inches deep or 8 sq ft at 3 inches deep. A 3 cu ft bag covers about 18 sq ft at 2 inches or 12 sq ft at 3 inches.
How deep should mulch be?
For most flower beds and borders, 2–3 inches (5–8 cm) is the usual recommendation. Thinner layers let weeds through, and very thick layers (over about 4 inches) can keep water and air from reaching the soil. Keep mulch a few inches away from tree trunks and plant stems.
How many litres of mulch do I need per square metre?
Depth in centimetres × 10 gives litres per square metre. At 5 cm you need 50 L per m², and at 7.5 cm you need 75 L per m².
Is it cheaper to buy mulch in bags or in bulk?
For small beds, bags are convenient and avoid delivery fees. For larger jobs, bulk mulch is usually cheaper per cubic yard, but suppliers often charge delivery. Enter both prices in the cost section above to compare for your job.
Should I remove old mulch before adding new mulch?
Not usually. If the old layer is still thin, rake it to loosen it and top up with about 1 inch (2–3 cm) of fresh mulch. If the total would end up deeper than about 4 inches, remove some of the old material first.
Last reviewed November 5, 2026.