Nothing kills the “curb appeal” high faster than realizing you’re five bags short of a finished garden bed—or worse, having a mountain of leftover mulch rotting on your driveway. In the landscaping world, mulch is sold by the cubic yard, and getting the math right is simpler than it looks.

One cubic yard covers 324 square feet at 1 inch deep. However, for weed suppression and moisture retention, the golden rule is a 3-inch depth. At that thickness, one yard covers approximately 100 square feet.

The 3-Step “Bulk” Formula

1. Calculate Square Footage: Measure the length and width of your beds ($L \times W$).
2. Determine Depth: Choose your depth in inches (usually 3″).
3. The “324” Rule: Multiply your square footage by your desired depth, then divide by 324.
   • Example: A 200 sq. ft. garden at 3 inches deep:
   • $200 \times 3 = 600$
   • $600 / 324 = 1.85 \text{ yards}$. Round up to 2 yards for safety.

Mulch Coverage Quick Reference

Use this table to estimate how many cubic yards you need based on a standard 3-inch depth:

Frequently Asked Questions

Is it cheaper to buy bulk or bagged? Generally, if you need more than 2 yards, bulk delivery is significantly cheaper. However, bagged mulch is easier to transport if you don’t have a truck or a spot to dump a “mulch mountain.”

Does mulch settle over time? Yes. Cedar and hardwood mulch can settle by 20%–30% after the first few rains. Always round your calculation up to the nearest half-yard to account for settling.

Can I mulch over old mulch? Only if the old layer has decomposed. If you have a “mulch volcano” building up, rake out the old material first to prevent root rot and allow oxygen to reach the soil.