How deep should mulch be? (The 2-3 inch rule)
Most landscaping projects work best with 2-3 inches of mulch. Here's what each depth gets you:
- 2 inches: looks clean, handles light weed control, fine for refresh jobs
- 3 inches: better weed blocking, holds moisture longer, standard for most beds
- 4 inches: heavy-duty but risky - can smother plants if you're not careful
What depth for different areas
- Flower beds and shrubs: 2-3 inches works every time
- Vegetable gardens: 1-2 inches, depends on what you're growing
- Pathways: 3-4 inches so it doesn't compact down to nothing
- Tree rings: 2-3 inches, but never pile it against the trunk
When in doubt, go with 3 inches. That's what most landscapers use for a standard mulch job.
Step 1: Measure your area in square feet
You probably know the length and width of your beds, but you need square footage for the math to work. Here's how to get it:
Rectangle or square beds
Area = length × width
Example: 10 ft long × 15 ft wide = 150 square feet
Circle (like a tree ring)
Area = π × r² (π is about 3.14)
Example: If your ring has a 3 ft radius → 3.14 × 3 × 3 = 28.3 square feet
Weird curvy shapes
Break them into smaller rectangles or triangles, calculate each piece, then add everything together. Good enough beats perfect here.
Step 2: Turn that into cubic yards
Bulk mulch gets sold by the cubic yard. That's a 3×3×3 foot cube, which equals 27 cubic feet.
1 cubic yard = 27 cubic feet
The formula that actually works
Cubic yards = (Square feet × Depth in inches) ÷ 324
Why 324? Because 27 cubic feet per yard times 12 inches per foot gives you 324. The math checks out, and this is way easier than converting inches to feet first.
One formula, that's it:
✅ cubic yards = (sq ft × inches) ÷ 324
Quick reference table (bookmark this)
At 3 inches deep:
- 100 sq ft ≈ 0.93 yards (call it 1 yard)
- 200 sq ft ≈ 1.85 yards (call it 2 yards)
- 300 sq ft ≈ 2.78 yards (call it 3 yards)
- 500 sq ft ≈ 4.63 yards (call it 5 yards)
At 2 inches deep:
- 100 sq ft ≈ 0.62 yards
- 200 sq ft ≈ 1.23 yards
- 300 sq ft ≈ 1.85 yards
- 500 sq ft ≈ 3.09 yards
Most homeowners end up ordering 2-6 yards for typical yard projects. Anything more means you have a bigger property or you're doing serious landscaping.
Step 3: If you're buying bags instead of bulk
Most bagged mulch comes in 2 cubic foot bags. Sometimes you'll see 1.5 or 3 cubic foot bags, but 2 is standard at most stores.
Here's the conversion math you actually need:
How many bags equal a yard?
Since 1 cubic yard = 27 cubic feet:
- 2 cu ft bags: 27 ÷ 2 = 13.5 bags, so call it 14 bags per yard
- 1.5 cu ft bags: 27 ÷ 1.5 = 18 bags per yard
- 3 cu ft bags: 27 ÷ 3 = 9 bags per yard
The bag formula
Bags needed = (Cubic yards × 27) ÷ Bag size in cu ft
Example: You need 2 yards and you're buying 2 cu ft bags → (2 × 27) ÷ 2 = 27 bags
Real example: Standard garden bed
Your bed: 20 feet long × 6 feet wide = 120 square feet
Depth you want: 3 inches
Cubic yards = (120 × 3) ÷ 324 = 360 ÷ 324 = 1.11 yards
So you need about 1.1 cubic yards.
If you're buying bags (2 cu ft)
1.11 yards × 14 bags per yard ≈ 15.5 bags
Always round up → 16 bags
✅ What to order:
- Bulk: order 1.5 yards (a bit extra never hurts)
- Bags: buy 16 bags of 2 cu ft size
Why 1.5 yards instead of 1.1? Most suppliers round to half-yard increments anyway, and running short halfway through a mulch job is annoying.
Real example: Backyard playground
Your play area: 15 ft × 15 ft = 225 square feet
Depth you want: 4 inches (playgrounds need thicker coverage for safety)
Cubic yards = (225 × 4) ÷ 324 = 900 ÷ 324 = 2.78 yards
That's about 2.8 cubic yards.
Bags (2 cu ft)
2.78 yards × 14 bags per yard ≈ 38.9 bags
Round up → 40 bags
✅ What to order:
- Bulk: order 3 yards
- Bags: buy 40 bags
For playground areas, bulk delivery makes way more sense than hauling 40 bags yourself. That's a lot of trips to the car.
Real example: Mulch ring around a tree
Say you want a nice mulch ring around a tree in your front yard:
Ring radius: 4 feet from the trunk
Area = 3.14 × 4² = 3.14 × 16 = 50.2 square feet
Depth you want: 3 inches
Cubic yards = (50.2 × 3) ÷ 324 = 150.6 ÷ 324 = 0.46 yards
That's about half a cubic yard.
Bags (2 cu ft)
0.46 yards × 14 bags per yard = 6.4 bags
Round up → 7 bags
✅ What to order:
- Bulk: ~0.5 yard (but most suppliers have minimums higher than this)
- Bags: 7 bags and you're done
Tree rings are perfect for bags. Grab 7-8 bags at the store, toss them in the car, done in 20 minutes. Way easier than dealing with bulk delivery minimums for such a small job.
Mistakes everyone makes (learn from them)
Forgetting that depth matters
People measure their beds but forget that depth is the multiplier. Going from 2 inches to 3 inches means 50% more mulch. That's not a rounding error, that's a whole extra trip or another yard you need to order.
Fix: Decide on 2-3 inches for beds, 3-4 inches for paths or play areas, then stick to it when you calculate.
Ordering the exact amount you calculated
Mulch isn't perfectly even. Your beds aren't perfect rectangles. The ground isn't level everywhere. If you order exactly what the math says, you're going to come up short and have thin spots.
Fix: Add 10% extra. If you calculated 3 yards, order 3.5. You'll thank yourself later.
Mixing up "yard" and "square yard"
This trips up so many people. They're completely different things:
- Cubic yard = volume, what mulch is sold in
- Square yard = area measurement, not how mulch works
Fix: When someone says "mulch by the yard," they always mean cubic yards. If they meant square yards, they'd say "square yards."
Ignoring slopes and curves
Sloped beds hold way more mulch than flat ones. Curved edges and irregular borders eat up more than you'd think. The formula assumes flat, straight beds.
Fix: Round up to the next half-yard or grab a few extra bags if your beds have slopes or curves.
Creating mulch volcanoes around trees
Piling mulch right up against the trunk looks tidy but it traps moisture, invites rot, and can kill the tree over time. This is called "mulch volcano" and every arborist hates it.
Fix: Keep mulch a few inches away from the trunk. Spread it evenly in a donut shape, not a volcano.
Should you buy bulk or bags?
Once you know how much you need, here's the simple decision tree:
Less than 1 yard
Go with bags. Easier, no delivery minimums, you can fit them in your car.
Between 1-2 yards
Could go either way. Check prices and delivery costs in your area. If the supplier offers free delivery and you don't want to haul 14-28 bags, get bulk delivered.
3 yards or more
Bulk wins on price and time. You don't want to move 40+ bags by hand.
Finding suppliers once you know how much you need
You've done the math. Now you need to find a place that can actually deliver or sell what you need:
- Want bulk delivered? Find a supplier that delivers to your area and check their minimum order size.
- Want bulk pickup? Make sure they sell by the yard and ask if they load it or you do.
- Want bags? Garden centers and hardware stores both work, compare prices.
This is exactly what MulchMap solves. Search by your city or zip code, filter by delivery or pickup, see what types they carry, and compare your options without calling 10 different places.
The whole workflow in order
- Measure your area in square feet
- Pick your depth (2-3 inches for most beds)
- Calculate cubic yards: (sq ft × inches) ÷ 324
- Convert to bags if that's how you're buying
- Find a supplier, check delivery fees and minimums, place your order