How Much Mulch Do I Need?

Quick answer: Multiply your bed's square footage by the desired depth (in feet), then divide by 27 to get cubic yards. For a 200 sq ft garden bed at 3 inches deep, you need about 1.85 cubic yards — roughly 25 bags (2 cu ft each).

Skip the math — use our free Mulch Calculator →

The Formula (Step by Step)

Measure your bed area — length × width in feet (for irregular shapes, break into rectangles)
Choose your depth — 2 to 4 inches is standard
Convert depth to feet — divide inches by 12 (3 inches = 0.25 ft)
Calculate cubic feet — area × depth in feet
Convert to cubic yards — divide by 27

Real Example: 10×20 Garden Bed, 3 Inches Deep

200 sq ft × 0.25 ft = 50 cubic feet
50 ÷ 27 = 1.85 cubic yards

Mulch Coverage Chart

One cubic yard of mulch covers:

2 inches deep: 162 sq ft
3 inches deep: 108 sq ft
4 inches deep: 81 sq ft

One bag (2 cu ft) covers:

2 inches deep: 12 sq ft
3 inches deep: 8 sq ft
4 inches deep: 6 sq ft

How Deep Should Mulch Be?

2 inches: Minimum for weed suppression. Fine for decorative beds with few weeds.
3 inches: The sweet spot. Good weed control, moisture retention, and insulation. Most landscapers recommend this.
4 inches: Maximum for most beds. Deeper than this can suffocate roots and trap too much moisture.
Around trees: 2–3 inches, starting 6 inches away from the trunk. Never volcano-mulch (piling mulch against the trunk).

Bags vs. Bulk: Which Is Cheaper?

Bulk is almost always cheaper for larger areas.

Bags (2 cu ft): $3–$5 each = roughly $40–$67 per cubic yard
Bulk delivery: $25–$45 per cubic yard + delivery fee ($30–$75)

Rule of thumb: If you need 3+ cubic yards, buy bulk. The delivery fee pays for itself quickly. Below 2 cubic yards, bags are more convenient.

Common Mistakes to Avoid

❌ Volcano mulching

Piling mulch up against tree trunks traps moisture and causes rot, disease, and pest problems. Keep mulch 6 inches away from trunks and 1 inch away from plant stems.

❌ Mulching too deep

More than 4 inches restricts oxygen and can cause root suffocation. It also creates a cozy home for rodents.

❌ Not refreshing old mulch

If existing mulch has decomposed to less than 1 inch, top it up. If it's matted and water-resistant, break it up with a rake before adding new mulch on top.

❌ Using the wrong type

Cedar and cypress are great for weed suppression. Pine straw works for slopes. Rubber mulch doesn't break down (good and bad). Don't use dyed mulch near edible gardens.

Pro Tips

Spring is mulch season. Apply after soil warms up in spring for best weed prevention.
Weed first. Mulch suppresses weeds — it doesn't kill existing ones.
Landscape fabric under mulch is optional. It helps short-term but degrades and becomes a maintenance headache. For most beds, 3 inches of mulch alone does the job.
Measure existing depth before adding more. You may only need 1 inch to top up.

Frequently Asked Questions

How many bags of mulch are in a cubic yard?

13.5 bags of 2 cu ft mulch = 1 cubic yard. Round up to 14 bags.

How often should I replace mulch?

Organic mulch (wood, bark) decomposes and should be topped up yearly. Full replacement every 2–3 years is typical. Inorganic mulch (rubber, rock) lasts much longer.

Does mulch attract termites?

Mulch doesn't attract termites, but it can provide a moist environment they like. Keep mulch 12 inches away from your foundation and you'll be fine. Cedar mulch is naturally termite-resistant.

How much does a cubic yard of mulch weigh?

About 400–800 lbs depending on moisture content and type. Dry pine bark is lighter; wet hardwood mulch is heavier. Plan your vehicle accordingly.

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