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Mulch & Soil Calculator - How Much Mulch Do I Need?

Miscellaneous

Calculate how much mulch or soil you need for garden beds. Enter bed dimensions and desired depth to get cubic feet, cubic yards, and bags to buy.

Your inputs are saved in this browser only. No data is ever sent to a server, and saved values won't be visible in other browsers or devices.

Bed 1

Area: 40 sq ft

Bed 2

Area: 18 sq ft
58
sq ft
14.5
cu ft
0.537
cu yd
8
@ 2 cu ft

How to use this tool

  1. Choose Imperial or Metric units.
  2. Enter the length and width of each garden bed.
  3. Set the desired mulch/soil depth.
  4. Enter the bag size (e.g., 2 cu ft) to see how many bags to buy.
  5. Read the total volume in cubic feet, cubic yards, and bags.

How to calculate mulch volume

Multiply the area of each garden bed (length × width) by the desired depth. Because depth is usually given in inches and area in square feet, divide the depth by 12 before multiplying to get cubic feet: 

Volume (cu ft) = Length (ft) × Width (ft) × Depth (in) / 12

Cubic feet vs. cubic yards

Bagged mulch is typically sold in 2 cu ft bags. Bulk mulch delivered by the truckload is sold by the cubic yard (27 cu ft). This calculator shows both so you can easily compare bagged and bulk pricing.

Recommended depth by material

  • Bark mulch / wood chips: 2–3 inches
  • Fine compost / topsoil: 1–2 inches as a top-dressing
  • Gravel / stone: 2–3 inches
  • Straw: 3–4 inches

Tips

  • Keep mulch 2–3 inches away from plant stems to prevent rot.
  • Add 10–15 % extra when buying to allow for settling and spillage.
  • Refresh mulch annually. It decomposes and thins over time.

Mulch types comparison

TypeRecommended depthProsCons
Wood chips / bark2–3 inWeed suppression, moisture retention, slow decompositionCan harbor insects if applied too thick
Shredded bark / nuggets2–3 inAttractive, widely available, good insulationFloats in heavy rain; pine can acidify soil
Straw3–4 inLightweight, great for vegetable gardensCan introduce weed seeds if not sterile
Rubber mulch2–3 inLong-lasting (10+ years), no decompositionGets hot in sun, can leach zinc, not organic
Gravel / stone2–3 inPermanent, great drainage, low maintenanceRetains heat, heavy, difficult to remove

Delivery quantities

Bagged mulch is commonly sold in 2 cu ft bags. To find how many bags you need, divide your total cubic feet by 2: 

Number of bags = Total volume (cu ft) ÷ 2

Bulk mulch from a landscape supplier is sold by the cubic yard (1 cu yd = 27 cu ft). Divide your total cubic feet by 27 to get the number of cubic yards. Bulk is almost always cheaper per cubic foot for large projects (3+ cu yd).

Volcano mulching warning

Volcano mulching - piling mulch against a tree trunk in a cone shape - is one of the most common and damaging landscaping mistakes. Mulch piled against bark traps moisture, promotes fungal disease and rot, and can attract rodents that girdle the bark. Keep mulch 2–3 inches away from the trunk and spread in a flat ring extending to the drip line.

Frequently asked questions

How deep should I apply mulch?

2–3 inches is the recommended depth for most gardens. Less than 2 inches may not suppress weeds effectively; more than 4 inches can prevent water from reaching roots and may cause root rot.

How many cubic feet are in a cubic yard?

One cubic yard equals 27 cubic feet (3 ft × 3 ft × 3 ft). Bulk mulch and soil are typically sold by the cubic yard, while bagged products are sold by the cubic foot.

How many bags of mulch cover a yard?

One cubic yard (27 cu ft) requires approximately 13–14 standard 2 cu ft bags, or 9 standard 3 cu ft bags.

Can I use this calculator for topsoil, compost, or gravel?

Yes. The volume calculation is the same for any material applied at a uniform depth. Just enter your desired depth and bed dimensions.

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