Mulch Calculator
See the depth guide below for typical uses.
Mulch needed
1.85 yd³
- Bed area
- 200 ft²
- Volume
- 50 ft³
- In 2 cu ft bags
- 25 bags
Cost comparison
$143.33 bulk vs $100.00 bagged
- Bulk delivered
- $143.33
- Bagged (25 bags)
- $100.00
- Verdict
- Bags are cheaper here
How deep should mulch be?
| Where | Depth | Note |
|---|---|---|
| Flower beds & borders | 2 in | Suppresses weeds, still lets water through |
| Around trees & shrubs | 3 in | Keep several inches off the trunk |
| Vegetable garden paths | 4 in | Heavier layer for traffic |
| Refreshing an existing bed | 1 in | Top-up only — old mulch still counts |
Volumes assume rectangular beds — curved or irregular borders need you to eyeball the square footage first. Bulk suppliers usually have a minimum order, which isn't included here. Laying stone instead of mulch? The gravel calculator quotes it by the ton the way suppliers sell it.
A 20 × 10 ft bed at 3 inches deep needs 1.85 cubic yards of mulch — 50 cubic feet, or 25 bags of the common 2 ft³ size. With the placeholder prices here, that's $100 in bags against $143.33 delivered in bulk ($45 per cubic yard plus a $60 flat delivery fee), so bags win on this job. The delivery fee is flat, which is exactly why small orders favor bags and large ones don't.
How much mulch do I need?
Mulch is sold by volume, and the unit to think in is the cubic yard:
area (ft²) = length (ft) × width (ft)
depth (ft) = depth in ÷ 12
volume (ft³) = area × depth
cubic yards = volume ÷ 27 ← 1 yd³ = 27 ft³ (a 3 × 3 × 3 ft cube)
bags = volume ÷ cubic feet per bag, rounded up
Worked example — the page default, a 20 × 10 ft bed at 3 inches:
- Area: 20 × 10 = 200 ft²
- Depth: 3 ÷ 12 = 0.25 ft → volume 50 ft³
- Cubic yards: 50 ÷ 27 = 1.85 yd³
- Bags: 50 ÷ 2 = 25 bags (2 ft³ bags)
Bulk delivery or bags?
| Job | Size & depth | Volume | Cubic yards | 2 ft³ bags | Bulk vs bagged |
|---|---|---|---|---|---|
| Flower bed (default) | 20 × 10 ft, 3 in | 50 ft³ | 1.85 | 25 | $143.33 vs $100 |
| Seasonal top-up | 20 × 10 ft, 1 in | 16.67 ft³ | 0.62 | 9 | $87.78 vs $36 |
| Border | 4 × 12 ft, 2 in | 8 ft³ | 0.30 | 4 | $73.33 vs $16 |
| Whole yard, deep | 30 × 19 ft, 4 in | 190 ft³ | 7.04 | 95 | $376.67 vs $380 |
The last row is the turning point. With a flat $60 delivery fee and $45 per cubic yard, bulk only starts to win at roughly 7 cubic yards — about 570 ft² at 4 inches deep. Below that you're mostly paying to have a truck show up. Change any of the three prices and the crossover moves, which is why the calculator shows both lines side by side instead of declaring a winner from a national average.
How deep should mulch be?
Deeper isn't better — too much mulch sheds water and can suffocate roots. The working guidance most extension services give:
- 1 inch — refreshing a bed that still has last year's mulch; old mulch still counts toward the total.
- 2 inches — flower beds and borders; enough to suppress weeds while still letting rain through.
- 3 inches — around trees and shrubs, kept several inches away from the trunk (mulch piled against bark is a common way to kill a tree).
- 4 inches — paths and vegetable-garden walkways that take foot traffic.
The depth field is where most estimating errors happen: going from 2 to 3 inches on the default bed is 1.23 → 1.85 yd³, a 50% jump in material for one inch.
The inputs people get wrong
- Shape. This page measures rectangles. For a circular bed, work out π × radius² yourself and enter the equivalent rectangle — a 10 ft circle is 78.5 ft², not 100 ft².
- Bag size. Garden centers sell 2 ft³ and 3 ft³ bags; the 3 ft³ bag on the default job is 17 bags instead of 25. Check the bag, not the price tag alone.
- Existing mulch. Topping up only needs the difference. If you already have 2 inches and want 3, set the depth to 1 inch.
How to use this calculator
- Enter bed length and width in feet.
- Set the depth in inches (3 is the default; see the guidance above).
- Pick your bag size — 2 ft³ or 3 ft³.
- Enter your supplier's price per cubic yard, the delivery fee, and the price per bag.
- Compare the two totals; remember bulk is quoted by the yard and bags by the bag.
Frequently asked questions
How much mulch do I need for 200 square feet?
1.85 cubic yards at 3 inches deep (50 ft³), or 25 bags of 2 ft³ mulch. At 2 inches it's 1.23 yd³ (17 bags); at 1 inch, 0.62 yd³ (9 bags).
How many bags of mulch are in a cubic yard?
13.5 bags of 2 ft³ mulch per cubic yard (27 ÷ 2), so 14 bags to cover a full yard — or 9 bags of 3 ft³ mulch.
How many square feet does a cubic yard of mulch cover?
108 ft² at 3 inches, 162 ft² at 2 inches, and 81 ft² at 4 inches — one cubic yard is 27 cubic feet, and coverage falls as depth rises.
Is bulk mulch cheaper than bagged?
Not automatically. Bulk carries a flat delivery fee, so on the default job bags cost $100 vs $143.33 delivered. With these placeholder prices bulk only wins past roughly 7 cubic yards; enter your own prices to find your crossover.
How deep should mulch be around trees?
About 3 inches, kept several inches clear of the trunk. Mulch heaped against the bark keeps it wet, invites rot and pests, and is one of the most common ways established trees get damaged.
Can I use this for a circular bed or an irregular border?
Not directly — this calculator measures rectangles. Work out the area first (π × radius² for a circle) and enter a rectangle of the same area, then add a little for the irregular edge.
Data sources: Volumes are pure geometry from the dimensions you enter (27 ft³ = 1 yd³). Bag sizes of 2 ft³ and 3 ft³ are the standard US garden-center offerings. Depth guidance (1 in to refresh, 2 in for beds, 3 in around trees kept off the trunk) reflects common cooperative-extension recommendations, not a rule written into the math. $45 per cubic yard, $60 delivery, and $4 per 2 ft³ bag are placeholders, not market quotes — replace them with your supplier's numbers, since the bulk-vs-bagged verdict depends entirely on them. Every figure on this page was produced by this calculator and can be reproduced with the same inputs. Related tools: gravel calculator, concrete calculator, all home project calculators, percentage calculator.