How to calculate mulch and soil
Mulch, soil, and compost are sold by volume, so the math is straightforward:
Cubic yards = area (sq ft) × depth (ft) ÷ 27
Since depth is usually measured in inches, divide it by 12 first. The calculator handles that and shows the volume in cubic yards (for bulk delivery), cubic feet, and bags (for smaller jobs).
How much does a yard of mulch cover?
One cubic yard is 27 cubic feet — about 13–14 of the standard 2-cubic-foot bags. Here's how far a cubic yard spreads at common depths:
| Depth | Coverage per cubic yard |
|---|---|
| 1 in | ~324 sq ft |
| 2 in | ~162 sq ft |
| 3 in | ~108 sq ft |
| 4 in | ~81 sq ft |
Recommended depths
| Use | Recommended depth |
|---|---|
| Refreshing existing mulch | 1–2 in |
| Standard garden beds | 2–3 in |
| New beds / weed suppression | 3–4 in |
| Topsoil for new lawns | 3–6 in |
Which mulch should you choose?
Different mulches trade off price, looks, and how long they last:
- Shredded hardwood. The most common, economical mulch. It knits together so it stays put on slopes and breaks down to feed the soil — which also means it needs topping up each year.
- Bark mulch (pine, fir). Chunkier nuggets that last longer and float less than fine bark; good around shrubs and trees.
- Pine straw. Lightweight, easy to spread, and slightly acidic — a favorite around azaleas, hydrangeas, and other acid-loving plants.
- Cedar or cypress. Aromatic, rot-resistant, and slow to break down; cedar's natural oils also help deter some insects.
- Dyed mulch. Hardwood colored black, brown, or red for a uniform look. Choose a reputable source so the dye is safe and the wood isn't recycled construction debris.
- Rubber mulch. Long-lasting and springy — common under playsets — but it doesn't improve soil and is hard to remove later.
- Stone or gravel. A permanent "mulch" for paths and xeriscapes; use the same volume math, but remember stone is sold by weight.
Bags vs. bulk: which is cheaper?
Bulk mulch runs about $20–$50 per cubic yard plus a delivery fee; bagged mulch is roughly $3–$6 for a 2-cubic-foot bag. Since it takes about 13–14 bags to equal a cubic yard, bags cost noticeably more per yard once you add them up — bulk delivery wins as soon as you need more than about a cubic yard, even after the delivery charge. Bags are still handy for small beds, tight access, or when you can't take a whole truckload.
Tips for mulching
- Don't overdo the depth. More than 3–4 inches can suffocate roots and trap moisture against stems.
- Keep mulch off trunks. Piling it against trunks ("mulch volcanoes") rots bark and invites pests — leave a few inches of clear space.
- Fluff before you add. Old mulch can be raked and turned to refresh its color before you decide you need more.
- Weed and edge first. Mulch suppresses new weeds but won't smother established ones — clear them and define the bed edge before you spread.