How Much Mulch for a 15×20 bed?
This calculator is pre-filled to estimate the mulch for a 15×20 bed. Change any field to match your project, and enter your local price for a precise cost.
Quick answer: A 15×20 bed at a 3 in depth needs about 2.78 cubic yards of mulch (75 cu ft) — roughly 38 2 cu ft bags.
Mulch calculator
How it's calculated: Bed length ft × width ft × (depth in ÷ 12) = cubic feet; divide by 27 for cubic yards, or by 2 for the number of 2 cu ft bags.
How to estimate mulch
- 2-3 inches suppresses weeds and holds moisture without smothering roots. Keep mulch off plant stems and trunks.
- One cubic yard equals about 13.5 bags of 2 cu ft mulch and covers ~100 sq ft at 3 inches.
- Bulk delivery is cheaper than bags once you need more than ~10-15 bags.
- Rake old mulch loose and break up any matted crust before topping up - a crusted layer sheds water instead of soaking it in.
- Have bulk mulch dumped onto a tarp - cleanup is faster and the driveway stays clean.
Frequently asked questions
How Much Mulch for a 15×20 bed?
A 15×20 bed at a 3 in depth needs about 2.78 cubic yards of mulch (75 cu ft) — roughly 38 2 cu ft bags.
How many bags of mulch in a cubic yard?
About 13.5 bags of the common 2 cubic foot size.
How deep should mulch be?
2-3 inches for most beds. Refresh annually to keep it near 3 inches.
How much area does a cubic yard of mulch cover?
About 100 sq ft at 3 inches deep, or around 160 sq ft at 2 inches.
When should I mulch?
Late spring after the soil warms, with an optional thinner top-up in fall. Mulching cold, soggy soil in early spring slows beds down.
Is bulk mulch cheaper than bagged?
Once a project passes 10-15 bags, bulk delivery is almost always cheaper per yard. Bags win for small beds, tight access, or when you need to haul it yourself.