Mulch Calculator
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What Your Result Means
- Cubic Feet: The total volume of mulch you need. This is the most precise measurement for comparing bag sizes or mixing different depths.
- Cubic Yards: The volume in yards, which is how bulk mulch is typically sold by landscape supply yards. One cubic yard equals 27 cubic feet and generally covers about 100–160 sq ft at a 2–3 inch depth.
- Bags (2 cu ft): The number of standard retail bags (2 cubic feet each) to buy, rounded up. Bags are convenient for small projects but more expensive per yard than bulk delivery.
How This Calculator Works
You enter the bed length and width in feet and the desired mulch depth in inches. The tool converts depth to feet, multiplies length × width × depth to get cubic feet, divides by 27 for cubic yards, and divides by 2 for bag count (rounded up). It assumes a uniform rectangular area and does not account for existing mulch depth or irregular bed shapes.
Quick Questions
How deep should I spread mulch?
Two to three inches is the standard recommendation for most ornamental beds. Going deeper than four inches can suffocate plant roots and trap too much moisture, while less than two inches breaks down quickly and may not suppress weeds effectively.
Should I buy bags or order bulk mulch?
For projects under about 3 cubic yards, bagged mulch from a garden center is convenient and easy to transport. For larger areas, bulk delivery is significantly cheaper per cubic yard and saves trips, though you will need a place to dump and stage it.
How often should mulch be replaced?
Organic mulches like wood chips and bark generally need refreshing once a year — typically in spring. Over time they decompose and thin out, losing their weed-suppression and moisture-retention benefits.
Does mulch type matter?
Yes. Hardwood bark lasts longer but decomposes slowly. Pine straw is lighter and works well on slopes. Rubber mulch does not decompose but is not suitable for edible gardens. Choose based on your bed type, aesthetics, and maintenance preferences.
Sources
- University of Minnesota Extension — Mulching Around Trees and Shrubs (depth recommendations, mulch types)
- Clemson HGIC — Mulch (application rates, mulch selection)
- Penn State Extension — Mulching Landscape Trees (proper mulch depth and placement)
Method & review
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.