# Mulch Calculator: Cubic Yards & Bags Needed

> Work out how many cubic yards or bags of mulch you need for rectangular beds, round beds and tree rings, and compare bulk delivery with bags.

**Quick answer:** To cover 100 square feet with 3 inches of mulch you need about 0.93 cubic yards, or 13 bags of 2 cu ft. One cubic yard covers 108 square feet at 3 inches deep. Formula: area × depth (inches ÷ 12) ÷ 27 = cubic yards.

_Last updated: October 4, 2026. Estimates only; confirm quantities with your supplier._

## How much mulch do I need?

Mulch is sold by the **cubic yard** in bulk and by the **cubic foot** in bags. Multiply the bed's area by the depth you want, then convert to the unit you are buying.

```
cubic feet = area (sq ft) × depth (in ÷ 12)
cubic yards = cubic feet ÷ 27
2 cu ft bags = cubic feet ÷ 2
```

For a round bed or tree ring, area = π × (outer radius² − trunk radius²). A 6-foot ring around a 1-foot trunk at 3 inches deep takes about 6.9 cubic feet — 4 bags.

### Worked example: three beds and a tree ring

A front yard has a 20 × 4 ft border (80 sq ft), a 10 × 6 ft bed (60 sq ft) and a 5 ft ring around a tree with a 6-inch trunk (π × (2.5² − 0.25²) ≈ 19.4 sq ft). The total is about 159 sq ft. At 3 inches deep that is 159 × 0.25 = 39.9 cubic feet, or **1.48 cubic yards**: 20 bags of 2 cu ft, or one bulk delivery. At $38 a yard that's about $56 in bulk, against about $90 for 20 bags at $4.50 — if you can accept a delivery fee under the savings.

### Mulch needed by area

| Bed area | 2 in deep | 3 in deep | 4 in deep |
| --- | --- | --- | --- |
| 50 sq ft | 0.31 yd³ | 0.46 yd³ | 0.62 yd³ |
| 100 sq ft | 0.62 yd³ | 0.93 yd³ | 1.23 yd³ |
| 250 sq ft | 1.54 yd³ | 2.31 yd³ | 3.09 yd³ |
| 500 sq ft | 3.09 yd³ | 4.63 yd³ | 6.17 yd³ |
| 1.000 sq ft | 6.17 yd³ | 9.26 yd³ | 12.35 yd³ |
| 2.000 sq ft | 12.35 yd³ | 18.52 yd³ | 24.69 yd³ |

### Mulch coverage chart

| Depth | 1 cubic yard 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 |

### How deep should mulch be?

Two to three inches suits most flower beds and shrub borders: enough to suppress weeds and hold moisture without smothering roots. Around trees, keep mulch a few inches away from the trunk — piling it against the bark (a "mulch volcano") invites rot and pests. For playground surfaces use 6–12 inches of engineered wood fiber or rubber mulch to meet safety guidelines.

### Which type of mulch?

| Type | Best for | Notes |
| --- | --- | --- |
| Hardwood bark | General beds | Breaks down in 1–2 years, improves soil |
| Cedar / cypress | Beds near the house | Naturally resists insects, lasts longer |
| Pine straw | Acid-loving plants | Light, easy to spread |
| Dyed mulch | Curb appeal | Color fades in about a year |
| Rubber | Playgrounds | Doesn't decompose; costly |

### How to spread mulch well

- Edge the bed and pull weeds first; a thin layer of cardboard under mulch smothers persistent weeds.
- Spread it evenly at the target depth. Keep it 2–3 inches away from stems and several inches from tree trunks.
- Water after spreading to settle it, and refresh with a thin top-up each spring rather than piling on a new thick layer.

### Bulk or bagged?

One cubic yard equals 13.5 two-cubic-foot bags. At typical prices bulk mulch is cheaper once you need about 2 cubic yards or more, but it requires delivery and somewhere to dump the pile. Bags are easier to carry and store for small beds.

### Bags or bulk: an example cost comparison

Prices below are examples only; use your local numbers. Assume a 2 cubic foot bag at $4.50 and bulk mulch at $38 per cubic yard.

| Mulch needed | Bags (2 cu ft) | Bag cost | Bulk cost |
| --- | --- | --- | --- |
| 1 yd³ | 14 | $63 | $38 |
| 2 yd³ | 27 | $122 | $76 |
| 3 yd³ | 41 | $185 | $114 |
| 5 yd³ | 68 | $306 | $190 |
| 8 yd³ | 108 | $486 | $304 |

At these example prices a cubic yard costs $60.75 in bags versus $38 in bulk, which is why bulk wins for larger jobs. Add any delivery fee to the bulk price before comparing.

### Mulch needed for common bed sizes

| Bed | Area | 2 in deep | 3 in deep |
| --- | --- | --- | --- |
| 4 × 8 ft | 32 sq ft | 0.20 yd³ | 0.30 yd³ |
| 5 × 20 ft | 100 sq ft | 0.62 yd³ | 0.93 yd³ |
| 10 × 10 ft | 100 sq ft | 0.62 yd³ | 0.93 yd³ |
| 10 × 30 ft | 300 sq ft | 1.85 yd³ | 2.78 yd³ |
| Tree ring, 6 ft wide | 28 sq ft | 0.17 yd³ | 0.26 yd³ |

### Mistakes that waste mulch

- **Too deep.** More than about 3 inches can hold too much moisture around roots.
- **Against the trunk.** Pull mulch back a few inches from tree trunks and stems so the bark can dry.
- **Not raking the old layer.** Loosen last year's mulch and add only what brings it back to depth.
- **Skipping the measurement.** Measure once, round up, and keep the number for next year.

## Frequently asked questions

### How many 2 cu ft bags of mulch are in a cubic yard?

A cubic yard contains 27 cubic feet, which is 13.5 bags of 2 cu ft mulch.

### How much area does one yard of mulch cover?

About 108 square feet at 3 inches deep, 162 square feet at 2 inches, or 81 square feet at 4 inches.

### How much mulch do I need for a 10×10 bed?

A 10 × 10 ft bed (100 sq ft) at 3 inches deep needs 25 cubic feet — about 0.93 cubic yards or 13 bags of 2 cu ft.

### How deep should mulch be around trees?

Two to four inches, spread in a wide ring, and pulled back a few inches from the trunk.

### How often should I replace mulch?

Top up with an inch or two each spring or every other year. Rake the old layer first so the total depth doesn't exceed 3–4 inches.

### Can mulch be too thick?

Yes. More than 4 inches can block water and oxygen and encourage fungus and rodents. Keep it 2–3 inches deep around plants.

### Is mulch cheaper by the bag or in bulk?

Bulk is usually cheaper per cubic foot once you need around 2 yards or more. Compare delivery fees — they can erase the savings on small orders.

### How do I measure an irregular bed?

Break it into rectangles and circles, calculate each, and add the results, or use the square footage calculator.

## Sources and further reading

- [Mulching trees and shrubs](https://extension.umd.edu/resource/mulching-trees-and-shrubs) — University of Maryland Extension
- [Mulching landscape trees](https://extension.psu.edu/mulching-landscape-trees) — Penn State Extension
- [Too much of a good thing: mulch volcanoes slowly kill trees](https://extension.illinois.edu/news-releases/too-much-good-thing-mulch-volcanoes-slowly-kill-trees) — University of Illinois Extension
- [NIST Special Publication 811: conversion factors](https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors) — National Institute of Standards and Technology