Mulch Calculator
Find how much mulch to buy for your beds and tree rings: the right depth for your mulch, cubic yards or litres, how many bags, and whether bags or bulk is cheaper.
Wood chips: usually 2–4 in (5–10 cm) deep; settle about 10%.
Keep mulch a few inches off the trunk.
For curvy beds: we use the average of the three widths.
Keep mulch a few inches off the trunk.
For curvy beds: we use the average of the three widths.
Keep mulch a few inches off the trunk.
For curvy beds: we use the average of the three widths.
Keep mulch a few inches off the trunk.
For curvy beds: we use the average of the three widths.
Keep mulch a few inches off the trunk.
For curvy beds: we use the average of the three widths.
Keep mulch a few inches off the trunk.
For curvy beds: we use the average of the three widths.
Recommended for wood chips: 2–4 in.
Push a finger or ruler down to the soil to measure what is left.
Fresh mulch packs down. Changes with the mulch until you type your own.
Leave empty to use the typical dry weight. Wet mulch can weigh twice as much.
Follows the usual bag for the mulch until you pick one yourself.
Some yards sell at least 1 cu yd (or 1 m³).
How your mulch is worked out
Bed area × the depth you add = volume, plus a little for settling, then ÷ the bag size.
- 1
Add up the beds
10 × 10 ft= 100 sq ft
- 2
Times the depth
3 in = 0.25 ft100 × 0.25= 25 cu ft
- 3
Add 10% for settling
25 × 1.1= 27.5 cu ft= 1.02 cu yd
- 4
Count the bags
27.5 ÷ 2 cu ft= 13.75= 14 bags
Read more: the formula, a worked example, depths for each mulch and how far a yard goes
Mulch is sold by volume: cubic yards or cubic metres in bulk, and cubic feet or litres in bags. So the job is to find the area of your beds, multiply by the depth you want to add, add a little because fresh mulch settles, then turn that into bags or a bulk order. For gravel, sand and topsoil by the ton use the gravel calculator; for odd-shaped areas the square footage calculator has more shapes.
The formula
rectangle = length × width
circle = π × (diameter ÷ 2)²
ring round a tree = π ÷ 4 × (outside² − trunk²)
oval = π ÷ 4 × length × width
free-form = length × (width 1 + width 2 + width 3) ÷ 3
triangle (sides a, b, c) = √(s × (s − a) × (s − b) × (s − c)), where s = (a + b + c) ÷ 2
area = each bed × how many like it, added up
depth to add = depth you want − mulch already there (0 for a new bed)
volume = area × depth to add
to order = volume × (1 + (settling % + waste %) ÷ 100)
bags = to order ÷ what one bag holds, rounded up
bags cost = bags × price per bag · bulk cost = larger of (to order, smallest order) × bulk price + delivery
bulk starts to win at about delivery ÷ (bag price per cu yd − bulk price per cu yd)
1 cu yd = 27 cu ft = 764.55 L · 1 m³ = 1,000 L · 1 cu yd covers 324 ÷ depth in inches sq ft
Worked example
A bed 10 ft long and 10 ft wide, with wood chips 3 in deep. The area is 10 × 10 = 100 sq ft. 3 in is 3 ÷ 12 = 0.25 ft, so the volume is 100 × 0.25 = 25 cu ft. Wood chips settle about 10%, so order 25 × 1.10 = 27.5 cu ft, which is 27.5 ÷ 27 = 1.02 cu yd (0.779 m³ or 779 litres). In 2 cu ft bags that is 27.5 ÷ 2 = 13.75, rounded up to 14 bags. At a typical 400 kg per m³ it weighs about 0.7787 × 400 = 311 kg (687 lb).
Cost, with the example prices: 14 bags × 4 = 56. Bulk is 1.0185 × 40 = 40.74, plus 60 delivery = 100.74. So bags are cheaper by 44.74. A 2 cu ft bag at 4 is 2 per cu ft, or 54 per cu yd, so bulk only wins above about 60 ÷ (54 − 40) = 4.29 cu yd.
How deep to spread each mulch
| Mulch | Usual depth | Settles about | Typical weight |
|---|---|---|---|
| Wood chips (arborist or wood chips) | 2–4 in (5–10 cm) | 10% | 674 lb/cu yd (400 kg/m³) |
| Shredded bark (shredded hardwood or bark) | 2–3 in (5–7.5 cm) | 15% | 674 lb/cu yd (400 kg/m³) |
| Bark nuggets (pine bark chunks) | 2–4 in (5–10 cm) | 5% | 506 lb/cu yd (300 kg/m³) |
| Straw or pine needles (loose; packs down a lot) | 3–6 in (7.5–15 cm) | 30% | 101 lb/cu yd (60 kg/m³) |
| Compost or leaf mould (fine, feeds the soil) | 1–3 in (2.5–7.5 cm) | 10% | 1,011 lb/cu yd (600 kg/m³) |
| Rubber mulch (shredded tyres; does not rot) | 1.5–3 in (4–7.5 cm) | 0% | 758 lb/cu yd (450 kg/m³) |
| Stone or gravel (decorative stone, pea gravel) | 2–3 in (5–7.5 cm) | 0% | 2,697 lb/cu yd (1600 kg/m³) |
| Lava rock (light, porous stone) | 2–3 in (5–7.5 cm) | 0% | 1,079 lb/cu yd (640 kg/m³) |
| Playground, wood chips (US CPSC) | at least 9 in | about 25% | — |
| Playground, shredded rubber (US CPSC) | at least 6 in | — | — |
Garden depths, settling and weights are common rules of thumb, not rules: they vary with how coarse and how wet the mulch is. The playground rows are minimum depths from the US Consumer Product Safety Commission's Public Playground Safety Handbook, which says loose fill can pack down by about a quarter, so lay it deeper; check the rules where you live. The US CPSC playground depths are summarised from the CPSC handbook and have not yet been checked line by line against it (12 October 2026).
How far 1 cubic yard and 1 m³ go
| Depth | 1 cu yd covers | One 2 cu ft bag covers |
|---|---|---|
| 1 in | 324 sq ft | 24 sq ft |
| 2 in | 162 sq ft | 12 sq ft |
| 3 in | 108 sq ft | 8 sq ft |
| 4 in | 81 sq ft | 6 sq ft |
| 6 in | 54 sq ft | 4 sq ft |
| Depth | 1 m³ covers | One 50 L bag covers |
|---|---|---|
| 2.5 cm | 40 m² | 2 m² |
| 5 cm | 20 m² | 1 m² |
| 7.5 cm | 13.3 m² | 0.67 m² |
| 10 cm | 10 m² | 0.5 m² |
| 15 cm | 6.7 m² | 0.33 m² |
Tips for spreading mulch
- Pull mulch a few inches away from tree trunks and plant stems. Piling it against the bark ("mulch volcanoes") can rot it.
- Check last year's mulch before you buy. If 1–2 in is left, a top-up of an inch or two is usually enough.
- Bulk mulch is often sold in half or whole yards. Ask about the smallest order and the delivery fee, then put both in Advanced.
Common questions
How much mulch do I need?
Multiply the bed area by the depth, then add a little for settling. A bed 10 ft by 10 ft is 100 sq ft. At 3 in deep (0.25 ft) that is 25 cu ft. Wood chips settle about 10%, so order 27.5 cu ft: 1.02 cubic yards, 0.78 m³ or 14 bags of 2 cu ft.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cu ft, so it fills 13.5 bags of 2 cu ft (buy 14) or 9 bags of 3 cu ft. A cubic metre is 1,000 litres: 20 bags of 50 L, 16.7 bags of 60 L (buy 17) or 13.3 bags of 75 L (buy 14). One cubic yard is about 765 litres.
How deep should mulch be?
As a rule of thumb, wood chips and bark go on 2–4 in (5–10 cm) deep, compost 1–3 in, rubber mulch 1.5–3 in and stone 2–3 in. Loose straw or pine needles need 3–6 in because they pack down a lot. Too deep can starve roots of air, so stay in the range.
How much does a yard of mulch cover?
One cubic yard covers 324 ÷ the depth in inches square feet: 162 sq ft at 2 in, 108 sq ft at 3 in and 81 sq ft at 4 in. A 2 cu ft bag covers 8 sq ft at 3 in. In metric, 1 m³ covers 20 m² at 5 cm and 10 m² at 10 cm.
Is it cheaper to buy mulch in bags or in bulk?
For small beds bags usually win, because bulk has a delivery fee. With example prices of 4 for a 2 cu ft bag (54 a cubic yard) and bulk at 40 a cubic yard plus 60 delivery, bulk only becomes cheaper above about 4.3 cubic yards. Put in your own prices to see your answer.
How much mulch do I need to top up a bed?
Old mulch rots down, so measure what is left and add only the difference. If 1 in is left and you want 3 in, add 2 in. On a 100 sq ft bed that is 16.7 cu ft, or 18.3 cu ft with 10% for settling: 10 bags of 2 cu ft. Pick "Top up" in Advanced.
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Made by Zulu Calculator, part of AlphaZulu LLC. Formulas are shown in full and rule figures are checked against official sources; see how we build calculators.