A 2–3 inch layer of mulch holds moisture, keeps roots cool and suppresses weeds. Too thin and weeds grow through; too thick and roots can suffocate. Mulch is sold in 2 or 3 ft³ bags or in bulk by the cubic yard, and bulk is usually much cheaper above about 3 yd³ – this calculator shows both prices so you can compare.
How to use the Mulch Calculator
- Bed shape
- Length (or diameter)
- Width
- Depth
- Bag size
- Price per bag
- Bulk price per cubic yard
- Every result field is editable: type into Mulch needed and Depth plus every other field update to match.
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the bed area (or length and width), the depth and the bag size. The volume is the area times the depth; the number of bags is that volume divided by the bag size, rounded up. Enter bag and bulk prices to compare.
Bags of mulch per area
| Area | 2 in deep (2 ft³ bags) | 3 in deep (2 ft³ bags) |
|---|---|---|
| 50 ft² | 5 | 7 |
| 100 ft² | 9 | 13 |
| 200 ft² | 17 | 25 |
| 300 ft² | 25 | 38 |
| 500 ft² | 42 | 63 |
| 1000 ft² | 84 | 125 |
Tips for an accurate estimate
- Plan driveways and paths in layers – a compacted base of larger stone does most of the structural work.
- Add 10–25% for compaction: loose stone shrinks once it is rolled or driven on.
- Ask the quarry whether prices are per US ton, metric tonne or cubic yard before comparing quotes.
- Grade surfaces at 1–2% so water runs off rather than soaking into the base.
Common mistakes to avoid
- Skipping the base layer or geotextile on soft soil, which leads to ruts and potholes.
- Using rounded stone (pea gravel, river rock) on surfaces that carry vehicles.
- Ordering compacted volume when the supplier delivers loose material.
Inputs explained
| Field | What to enter |
|---|---|
| Bed shape | Choose one: Rectangle / square, Circle (length = diameter), Triangle (length = base, width = height) |
| Length (or diameter) | Units: ft, m, in, yd, cm |
| Width | Units: ft, m, in, yd, cm |
| Depth | Units: in, cm, mm, ft, m |
| Bag size | Choose one: 2 ft³, 3 ft³, 1.5 ft³, 50 L … |
| Price per bag | Units: /bag |
| Bulk price per cubic yard | Units: /yd³, /m³, /ft³ |
What each result means
- Mulch needed = [Bed area]×[Depth]
- Bags needed = ceil([Mulch needed]÷[Bag size])
- Cost with bags = [Bags needed]×[Price per bag]
- Cost in bulk = [Mulch needed]×[Bulk price per cubic yard]
- Approximate weight (wood mulch) = [Mulch needed]×400
Formula
Volume = area × depthBags = volume ÷ bag size (rounded up)Cost = bags × bag price (or volume × bulk price)Worked example
Inputs — Bed shape: Rectangle / square; Length (or diameter): 20 ft; Width: 10 ft; Depth: 3 in; Bag size: 2 ft³; Price per bag: $4.5 /bag; Bulk price per cubic yard: $40 /yd³.
Results — Bed area = 200 ft²; Mulch needed = 1.85 yd³; Bags needed = 25; Cost with bags = $112.50; Cost in bulk = $74.07; Approximate weight (wood mulch) = 1,249 lb.
Frequently asked questions
How deep should mulch be?
2–3 in for most beds, up to 4 in for paths; keep it a few inches away from tree trunks and stems.
How many bags of mulch are in a yard?
13.5 bags of 2 ft³ or 9 bags of 3 ft³.
How much area does a yard of mulch cover?
About 108 ft² at 3 in deep or 162 ft² at 2 in.
When is bulk mulch cheaper?
Usually beyond 2–3 yd³, but add the delivery fee to the bulk price.
What formula does the Mulch Calculator use?
Volume = area × depth.