Mulch & Soil Calculator
Calculate exactly how many bags or cubic yards of mulch, soil, or compost you need for your garden beds.
Garden Bed Size
You Will Need
Standard 2 cu ft bags (Home Depot/Lowe's)
Bulk delivery from nursery
When to buy bulk:
If you need more than 13 bags, it is usually cheaper to buy a full cubic yard delivered in bulk.
Last updated: August 2026
Stop Guessing Bags at the Garden Center
Buying mulch or soil without measuring first usually leads to multiple frustrating trips to the home improvement store. Whether you're top-dressing a small garden bed or laying down a deep layer for weed suppression, calculating your exact cubic yardage saves time, money, and back-breaking labor.
How to Use This Tool
Enter the length and width of your garden beds and your desired depth (3 inches is standard for mulch). The tool will output your total volume in cubic yards and tell you exactly how many standard 2-cubic-foot bags you need to buy if you aren't ordering in bulk.
The Formula
Length (ft) × Width (ft) × (Depth in inches ÷ 12) = Cubic Feet
From there: Cubic Feet ÷ 27 = Cubic Yards, and Cubic Feet ÷ 2 = Number of Standard Bags (each standard bag holds 2 cubic feet).
Worked Example
Say you have a garden bed 20 ft long and 5 ft wide, and you want a 3-inch layer of mulch:
- Cubic feet: 20 × 5 × (3 ÷ 12) = 20 × 5 × 0.25 = 25 cubic feet
- Cubic yards: 25 ÷ 27 ≈ 0.93 cubic yards (rounded up to be safe)
- Bags needed: 25 ÷ 2 = 12.5, rounded up to 13 bags
Since 13 bags is right at the bulk-buying threshold (1 cubic yard = 13.5 bags), this particular project is a toss-up — either a bulk delivery or a stack of bags at the store would work out to a similar cost, so convenience can be the deciding factor.