Mulch & Topsoil Calculator
Calculate cubic yards or bags of mulch, topsoil, compost, or gravel for your landscaping project.
Area Measurements
Mulch: 2-4". Topsoil: 3-6". Gravel: 2-4"
Your Estimate
Bags Required
0
bags of material
Volume
The Math Behind the Calculator
Landscape Material Formula
Cubic Yards = (L x W x D/12) / 27
27 cubic feet = 1 cubic yard. Depth in inches is converted to feet.
Bags vs. Bulk Delivery
| Quantity | Recommendation | Why |
|---|---|---|
| < 2 cubic yards | Bags | Convenient, no minimum |
| 2-4 cubic yards | Either | Compare prices, delivery fees |
| > 4 cubic yards | Bulk delivery | Much cheaper per yard |
Cost Comparison Example
For 3 cubic yards of mulch:
- Bags: ~40 bags @ $4 each = $160
- Bulk: 3 yards @ $35/yard + $50 delivery = $155
At 3+ yards, bulk is cheaper AND saves hours of loading/unloading bags.
Recommended Depths by Material
Mulch
- 2-3 inches: Annual flower beds, refreshing existing mulch
- 3-4 inches: Perennial beds, trees, shrubs
- 4+ inches: Play areas, pathways (use wood chips)
Warning: Too deep mulch (6"+) can harm plants and attract rodents.
Topsoil
- 2-4 inches: Lawn overseeding, light amendment
- 4-6 inches: New garden beds, lawn installation
- 8-12 inches: Raised bed fill, major grading
Gravel/Stone
- 2 inches: Decorative top dressing
- 3-4 inches: Walkways, driveways (over base)
- 4-6 inches: French drain fill
Compost
- 1-2 inches: Top dressing existing beds
- 2-4 inches: Amendment for new beds (till in)
- 25-50%: Mix ratio for container soil
Types of Mulch Compared
| Type | Lifespan | Best For | Notes |
|---|---|---|---|
| Hardwood bark | 1-2 years | General landscaping | Most common |
| Cedar mulch | 2-3 years | Insect-prone areas | Natural pest repellent |
| Pine bark | 1-2 years | Acid-loving plants | Lowers soil pH |
| Dyed mulch | 2-3 years | Color consistency | May contain recycled wood |
| Rubber mulch | 10+ years | Playgrounds | Doesn't decompose |
| Pine straw | 6-12 months | Slopes, acidic soil | Interlocks on hills |
Pro Tips for Mulch Application
Clear the Area First
Remove weeds and old decomposed mulch. Consider laying landscape fabric for weed control (optional but helpful around shrubs).
Keep Mulch Away from Stems
Leave a 2-3 inch gap around tree trunks and plant stems. "Volcano mulching" (piling mulch against trunks) causes rot and disease.
Edge Before Mulching
Create a clean edge between lawn and beds (use a spade or edger). A 3-4" trench keeps mulch contained.
Timing Matters
Apply mulch in spring after soil warms, or fall before frost. Mid-summer application can keep soil too cool. Water beds before and after mulching.
Frequently Asked Questions
How often should I replace mulch?
Most organic mulches need refreshing annually. Add 1-2 inches on top of existing decomposed mulch. Every 3-4 years, remove old mulch completely to prevent buildup.
Can I put new mulch over old mulch?
Yes, but first loosen the old layer with a rake. If old mulch is more than 3-4 inches deep after settling, remove some before adding new. Total depth shouldn't exceed 4 inches.
Does mulch attract termites?
Mulch doesn't attract termites, but provides habitat if they're already present. Keep mulch 6-12 inches away from your home's foundation to reduce risk. Cedar mulch may deter them slightly.