Landscaping calculators
Mulch Calculator
Work out how much mulch you need for garden beds, borders and tree rings. Calculate cubic yards, whole bags and optional material costs.
- Multiple beds
- New layer or top-up
- Imperial & metric
Coverage
How much area does one cubic yard of mulch cover?
One cubic yard is 27 cubic feet — enough for 324 square feet at 1 inch deep. Coverage falls as depth rises.
| Depth | Area covered by 1 yd³ | 2 ft³ bags per yd³ |
|---|---|---|
| 1 in (25 mm) | 324 sq ft | 13.5 (buy 14) |
| 2 in (51 mm) | 162 sq ft | 13.5 (buy 14) |
| 3 in (76 mm) | 108 sq ft | 13.5 (buy 14) |
| 4 in (102 mm) | 81 sq ft | 13.5 (buy 14) |
Geometric coverage before any allowance or settling. These depths illustrate the arithmetic; they are not planting recommendations.
Measuring
Measure your mulch beds in three steps
- 1 · Shape and area
Measure the area
For straight borders measure length and width. Break curved or irregular beds into rectangles, circles and triangles, and add each as a separate bed.
- 2 · Depth
Decide the depth to add
For an existing bed, measure what is left with a ruler. If 1.5 in remains and you want 3 in, you are adding 1.5 in — or use the top-up mode.
- 3 · Buying
Check the buying quantity
Bags round up to whole bags. Bulk suppliers may have a minimum order and sell in steps such as half-yards — ask before you order.
Formula
How the mulch calculation works
The worked example below is a 20 ft × 10 ft bed with 3 inches of mulch and an optional 10% allowance. The numbers are produced by the same code as the calculator.
Core equation (imperial)
Cubic yards = Area (sq ft) × Depth (in) ÷ 324
324 = 27 cubic feet per cubic yard × 12 inches per foot.
- Step 1 Convert depth to feet 3 in ÷ 12 = 0.25 ft
- Step 2 Cubic feet 20 × 10 × 0.25 = 50.00 ft³
- Step 3 Cubic yards 50.00 ÷ 27 = 1.85 yd³
- Step 4 Optional 10% allowance 50.00 × 1.10 = 55.00 ft³ (2.04 yd³)
- Step 5 Whole 2 ft³ bags 55.00 ÷ 2 = 27.5 → 28 bags
Buying
Bags or bulk delivery?
The volume is the same either way; what changes is how it is packaged, priced and delivered.
Bagged mulch
- Easy to carry to back gardens and to store until you are ready.
- You buy whole bags, so small jobs waste little.
- Usually a higher price per cubic yard — compare using your local prices.
Bulk delivery
- No packaging to dispose of.
- Delivered in one pile, so plan where it can be tipped and how you will move it.
- Delivery fees, minimum orders and sales increments can outweigh a lower yard price on small jobs.
Next steps
Related tools and measurement guides
Calculators
Questions
Mulch estimation questions
How do I calculate how much mulch I need?
Find the bed's area in square feet, multiply by the depth of mulch you are adding in inches, and divide by 324 to get cubic yards. A 20 ft × 10 ft bed (200 sq ft) at 3 in is 200 × 3 ÷ 324 = 1.85 cubic yards.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it takes 13.5 bags of 2 ft³ (buy 14) or 9 bags of 3 ft³. Always use the volume printed on the bag. If you are covering several beds with the same mulch, add them together first and round up once — that avoids buying a spare part-bag for every bed.
How do I calculate a top-up over existing mulch?
Choose Top up existing mulch. Push a ruler down to bare soil to measure the depth that is left, then enter your target depth and the existing depth. The calculator uses target − existing. If the existing layer is already as deep as your target, the result is zero and nothing needs to be bought.
How deep should mulch be?
That depends on the plants and the mulch, so the calculator does not assume a depth. For mulching trees and shrubs, the University of Maryland Extension advises keeping mulch shallow, one to three inches, and keeping it about 3 inches away from the base of tree trunks.
How do I measure a tree ring?
Choose the Tree ring shape. Enter the outer diameter of the mulched ring and the inner diameter of the area you will leave bare around the trunk. The calculator subtracts the inner circle: area = π × (outer radius² − inner radius²).
Should I add an extra allowance?
It is optional and set to 0% by default. You might add a little for uneven ground or for measuring uncertainty. The calculator shows the allowance on its own line and applies it only once.
Is bulk mulch cheaper than bags?
It depends on your quotes. Bulk is often priced lower per cubic yard, but delivery fees, minimum orders and the supplier’s sales increments can outweigh that on small jobs. Enter your actual prices in the bulk vs bags calculator to compare.