Mulch Calculator
Calculate exact mulch volume in cubic yards, cubic meters, and bag counts for rectangular or circular garden beds.
Total Volume Needed
How to Use This Mulch Calculator
Calculating garden mulch prevents buying excess bulk mulch or shortchanging flower beds. Use this tool with simple steps:
- Bed Shape: Select rectangular for standard landscape borders or circular for tree rings and round planters.
- Bed Dimensions: Enter garden length and width (or diameter) in feet or meters.
- Mulch Layer Depth: Select desired depth in inches or centimeters (standard recommended depth is 3 inches).
- Bag Size: Choose your local store bag size (standard retail bags contain 2.0 cubic feet of wood mulch).
Mulch Formulas & Conversion Standards
Landscape calculations convert surface area square footage and layer depth inches into cubic yards or bag counts:
Cubic Yards Formula
Area in square feet multiplied by depth in feet divided by 27:
Cubic Yards = (Square Feet x (Depth / 12)) / 27
Mulch Bag Conversion
One cubic yard contains 27 cubic feet. That equals 13.5 two-cubic-foot bags:
Bags = Cubic Feet / Bag Size (cu ft)
Mulch Depth & Quantity Quick Reference Table
Estimated mulch quantities required to cover a 100 square foot garden bed at various layer depths.
| Layer Depth | Recommended Application | Cubic Feet | Cubic Yards | Bags (2.0 cu ft) |
|---|---|---|---|---|
| 1 Inch (2.5 cm) | Topdressing existing mulch | 8.3 cu ft | 0.31 Yards | 5 Bags |
| 2 Inches (5.0 cm) | Light weed suppression | 16.7 cu ft | 0.62 Yards | 9 Bags |
| 3 Inches (7.5 cm) | Standard new garden bed | 25.0 cu ft | 0.93 Yards | 13 Bags |
| 4 Inches (10.0 cm) | Heavy weed barrier & walkways | 33.3 cu ft | 1.23 Yards | 17 Bags |
Frequently Asked Questions
How many bags of mulch equal one cubic yard?
One cubic yard equals 27 cubic feet. If you buy standard 2.0 cubic foot bags, you need 13.5 bags (14 full bags) to equal one cubic yard of bulk mulch.
How deep should mulch be laid in flower beds?
A depth of 3 inches is optimal for suppressing weeds and conserving moisture. Laying mulch deeper than 4 inches can smother plant root systems and block water penetration.
When is buying bulk mulch cheaper than buying bagged mulch?
Buying bulk mulch delivered by dump truck is generally more cost efficient when your project requires more than 2 to 3 cubic yards (27 to 40 bags). For small garden beds, bagged mulch offers easier transport.
Does wood mulch settle over time?
Yes. Organic wood mulch compresses and decomposes by approximately 15 to 20 percent over the first season. Adding a light 1-inch topdressing layer each spring maintains proper soil protection.
