HMHomestead Math
Garden & Compost

Raised Bed Soil Calculator

Calculate cubic feet, yards, bags, and soil mix.

Free calculatorDefaults are prefilled so the estimate appears immediately.

Your Estimate

35.2 cubic feet of soil

Cubic yards1.3 cu yd
Bags needed24
Bagged cost$216
Topsoil portion17.6 cu ft
Compost portion10.6 cu ft
Aeration portion7 cu ft

Formula Used

soil volume = length x width x depth in feet x settling adjustment

  • Depth is converted from inches to feet before multiplying length and width.
  • Settling allowance adds extra volume because loose mixes compact after watering.
  • Cubic yards divide cubic feet by 27.
  • Bag count rounds up because partial bags still require purchasing a whole bag.
  • Bulk soil may be cheaper for larger beds, but compare delivery and quality.
  • Soil mixes settle after watering and the first season.

What Is The Raised Bed Soil Calculator?

A raised bed soil calculator estimates how much soil or growing mix is needed to fill a rectangular bed. It converts cubic feet to cubic yards and bag counts, then gives a simple soil mix breakdown for planning purchases.

How To Use This Calculator

  1. Enter bed length and width.
  2. Enter soil depth in inches.
  3. Choose a settling allowance.
  4. Select bag size and cost if buying bagged mix.
  5. Use cubic feet, cubic yards, and bag counts to compare bulk and bagged options.

How Is It Calculated?

Formula

soil volume = length x width x depth in feet x settling adjustment

What The Constants Mean

  • Depth is converted from inches to feet before multiplying length and width.
  • Settling allowance adds extra volume because loose mixes compact after watering.
  • Cubic yards divide cubic feet by 27.
  • Bag count rounds up because partial bags still require purchasing a whole bag.

An 8 by 4 foot bed filled 12 inches deep with 10% settling allowance needs about 35.2 cubic feet, or about 24 bags if each bag is 1.5 cubic feet.

Why This Matters

Raised beds are easy to underestimate because depth adds volume quickly. A bed filled too shallowly may dry out fast or limit roots, while buying too much mix is expensive. Soil quality matters as much as volume, so match the mix to the crops and drainage conditions.

Homestead Math calculators are designed to make practical estimates visible. They are intentionally transparent: the inputs are labeled, the formula is shown, and the result is paired with cautions so you can decide what to verify locally before spending money or changing a setup.

Frequently Asked Questions

How deep should a raised bed be?

Many vegetable beds use 10 to 12 inches or more, though crop roots and site soil change the ideal depth.

Should I include settling?

Yes. Fresh mixes often settle after watering and the first season.

Is bulk soil cheaper than bags?

Often yes for larger beds, but delivery fees and soil quality should be compared.

What soil mix should I use?

A balanced mix commonly includes mineral soil, compost, and drainage/aeration material, adjusted for local needs.

Sources And References