Enter your garden bed size and depth — get an instant bag count, cubic yards, and a bulk vs bag recommendation.
⚡ Quick Answer
At 3 inches deep using standard 2 cu ft bags:
a 4×8 raised bed needs 4 bags,
a 10×10 area needs 13 bags,
and a 20×20 area needs 50 bags.
Not sure about your size? Use the calculator below — it handles any dimensions and any bag size.
🟢 2 inches — Minimum, light moisture retention
🟢 3 inches — Ideal for most garden beds
🟡 4 inches — Maximum recommended
🔴 5+ inches — Too deep, can harm roots
When in doubt, go with 3 inches.
Bags vs Bulk — Which to Choose?
Buy bags if you need fewer than 40 bags — easier to handle and no delivery to schedule.
Consider bulk if you need more than 3 cubic yards — sold by the yard at landscape suppliers, and delivery cost varies by location.
Get a bulk quote from your local supplier and compare. Our calculator shows cubic yards to make that easy.
How Far Does One Bag Go?
One 2 cu ft bag covers:
• 12 sq ft at 2 inches deep
• 8 sq ft at 3 inches deep
• 6 sq ft at 4 inches deep
One cubic yard covers:
• 162 sq ft at 2 inches
• 108 sq ft at 3 inches
• 81 sq ft at 4 inches
Bags Needed for Every Common Garden Size
Standard 2 cu ft bags · Rounded up so you never run short · Cubic yards shown at 3″ depth for bulk comparison
Garden Bed Size
2″ Deep
3″ Deep
4″ Deep
Cu Yds (3″)
4 × 4
2
2
3
0.15
4 × 8 (raised bed)
3
4
6
0.30
4 × 12
4
6
8
0.44
6 × 10
5
8
10
0.56
8 × 10
7
10
14
0.74
10 × 10
9
13
17
0.93
10 × 20
17
25
34
1.85
15 × 20
25
38
50
2.78
20 × 20
34
50
67
3.70
20 × 30
50
75
100
5.56
25 × 40
84
125
167
9.26
Bag counts are rounded up to the nearest whole bag. Based on 2 cu ft bags. Use the calculator above for other bag sizes or irregular shapes.
Frequently Asked Questions
How many bags of mulch do I need for a 10×10 area?
A 10×10 garden bed at 3 inches deep needs 13 bags of standard 2 cu ft mulch. At 2 inches deep you need 9 bags. At 4 inches deep you need 17 bags. Find your exact size in the table above or enter your dimensions in the calculator.
How many bags of mulch do I need for a 20×20 area?
A 20×20 garden area at 3 inches deep needs 50 bags of 2 cu ft mulch — that’s 3.70 cubic yards. At that volume, it’s worth calling a local landscape supplier for a bulk price before buying bags. Delivery fees vary, so compare both options.
How many bags of mulch are in a cubic yard?
One cubic yard of mulch equals 27 cubic feet. A standard 2 cu ft bag covers 2/27 of a cubic yard, so you need 14 bags to fill one cubic yard (always round up). One cubic yard covers 108 square feet at 3 inches deep — useful when comparing bulk pricing.
Is it cheaper to buy mulch in bags or bulk?
For smaller projects under 40 bags, bagged mulch is easy and the difference is often small. For larger projects, bulk mulch by the cubic yard can be less expensive — but delivery costs vary widely. Our calculator shows cubic yards so you can get a quote from your local supplier and compare directly.
How deep should mulch be?
Three inches is the sweet spot for most garden beds — enough to keep weeds down and hold moisture without causing problems. Two inches works for light coverage. Four inches is the maximum: going deeper can repel water and suffocate shallow roots.
Should I remove old mulch before adding new?
Usually no. Adding 1 to 2 inches on top each spring is the standard approach — old mulch breaks down over time and adds organic matter to your soil. Remove it only if it has gone moldy, developed a sour smell, or become water-repellent.