You need mulch. You don't know how much to order. You either overbuy and waste money or underbuy and have to make a second trip. This guide fixes that.
The mulch calculator at LandscapeCalculator.net handles the math instantly — but understanding the formula yourself means you can adjust on the fly without pulling out your phone every time.
The Formula
Mulch is sold by the cubic yard. One cubic yard is 3 feet × 3 feet × 3 feet — 27 cubic feet of material. Here's the calculation:
If your bed is 20 feet long and 8 feet wide and you want 3 inches of mulch:
(20 × 8 × 3 ÷ 12) ÷ 27 = 40 ÷ 27 = 1.48 cubic yards
Round up. Order 1.5 or 2 yards. Mulch settles after rain and you're better off with a little extra than coming up short around the edges.
What Depth Should You Use?
This is where most people get it wrong. They eyeball it or just do what they did last time. Here's the actual guidance:
| Situation | Recommended Depth | Notes |
|---|---|---|
| General flower beds | 2–3 inches | Sweet spot for weed control + moisture |
| Tree rings | 2–3 inches | Keep away from trunk — no volcano mulching |
| Slopes or hillsides | 3–4 inches | Thicker to prevent washout |
| Playgrounds / paths | 4–6 inches | Cushion requirement changes the math |
| Weed suppression priority | 3–4 inches | Under 2 inches and most weeds push through |
| Over existing mulch | 1 inch top-dress | If old layer is under 2 inches total |
Don't go over 4 inches on most plants. Thick mulch can create a moisture barrier that actually prevents rain from reaching roots and encourages fungal rot at the crown.
Bag vs. Bulk: What Actually Makes Sense
Bags are convenient. Bulk is almost always cheaper once you go over 2–3 cubic yards.
📦 Bagged Mulch
- 2 cu ft bags ≈ $5–$8 each
- 13.5 bags = 1 cubic yard
- 1 yard via bags ≈ $70–$110
- Good for small, tight spots
- Easy to store leftover bags
🚛 Bulk Delivery
- $25–$55 per cubic yard
- Delivery usually $50–$80 flat
- Best for 3+ cubic yards
- Faster to spread on large areas
- Much better price-per-yard
The break-even point is roughly 3 yards. Below that, bags are fine. Above that, call a landscape supplier and ask about bulk delivery minimums — most start at 2–3 yards anyway.
How Much Does Mulch Cost?
| Mulch Type | Bulk (per cu yd) | Installed w/ Labor |
|---|---|---|
| Shredded Hardwood | $25–$45 | $65–$110/yd |
| Dyed Black or Red | $30–$50 | $70–$120/yd |
| Cedar / Cypress | $35–$60 | $75–$130/yd |
| Pine Bark Nuggets | $22–$40 | $60–$100/yd |
| Rubber Mulch | $80–$130 | $150–$220/yd |
Common Mistakes
- Volcano mulching around trees — piling mulch against the trunk traps moisture and causes rot. Keep a 2–3 inch gap.
- Not edging first — mulch without defined edges spreads onto lawn and looks messy within a month.
- Ordering by bags for large areas — 8 cubic yards via bags costs 2× what bulk costs. Do the math before you go to the store.
- Skipping old mulch removal when it's compacted — if your existing layer is matted, water won't penetrate. Pull it out before adding fresh mulch.
- Using colored mulch near light-colored houses — dye bleeds when wet and can stain siding and concrete.
One More Thing on Mulch Depth
If you're refreshing existing beds, you don't always need a full 3-inch application. Measure what's there first. If it's already 2 inches of good material, a 1-inch top-dress is enough to refresh the color and surface coverage. That's a third of the material cost compared to a full re-application.
Use the free mulch calculator to run the numbers for your specific beds before ordering. It takes 30 seconds and beats guessing every time.
📖 For deeper guidance on mulch types and plant compatibility, the Utah State University Extension mulch guide is one of the most thorough free resources available.
Related Calculators
Once your mulch is sorted, you might also need to figure out how much topsoil to add to new beds, or check whether you need landscape rock for low-maintenance areas. Both calculators are free on this site.