Skip to content

Compost Calculator

Calculate compost bin capacity, material ratios, and estimated composting time. Optimize your composting process with our calculator.

Calculate Your Compost

Imperial (ft)

Bin Dimensions

Material Ratio (Optional)

Kitchen scraps, grass clippings, fresh leaves

Dry leaves, straw, paper, cardboard

Material Ratio (Optional)

Estimated Time:

Enter your bin dimensions to calculate:

  • Total bin volume and capacity
  • Material ratios for optimal composting
  • Estimated composting time
  • Processing capacity

How to Use the Compost Calculator

Our compost calculator helps you determine the perfect bin size and material ratios for efficient composting. Enter your bin dimensions to find its capacity, or use the ratio calculator to optimize your composting mix.

Optimal Composting Ratios

  • Green Materials (Nitrogen): Kitchen scraps, fresh grass clippings, coffee grounds
  • Brown Materials (Carbon): Dry leaves, straw, paper, sawdust
  • Ideal Ratio: 3 parts brown to 1 part green (3:1)
  • Moisture: Should feel like a wrung-out sponge

Common Bin Sizes

  • Small: 3x3x3 ft (0.9x0.9x0.9 m) = 27 ft³ (0.76 m³)
  • Medium: 4x4x3 ft (1.2x1.2x0.9 m) = 48 ft³ (1.36 m³)
  • Large: 4x4x4 ft (1.2x1.2x1.2 m) = 64 ft³ (1.81 m³)

Composting Tips

  • Turn your compost weekly for faster decomposition
  • Chop materials into smaller pieces to speed up the process
  • Keep compost moist but not waterlogged
  • Add both green and brown materials regularly
  • Monitor temperature - active compost should be warm

What to Compost

Do Compost

  • Fruit and vegetable scraps
  • Coffee grounds and filters
  • Eggshells
  • Grass clippings
  • Leaves
  • Shredded paper

Don't Compost

  • Meat or fish
  • Dairy products
  • Pet waste
  • Diseased plants
  • Weeds with seeds
  • Treated wood

Volume Conversions

  • 1 cubic foot = 28.3 liters = 7.48 gallons
  • 1 cubic yard = 27 cubic feet = 765 liters
  • 1 cubic meter = 35.3 cubic feet = 1000 liters

Compost Bag Sizes

  • Imperial: 20, 30, 40, and 50 cubic feet bags
  • Metric: 500L, 750L, 1000L, and 1500L bags

Ready to Design Your Garden?

Use our AI-powered garden planner to create sustainable garden designs that incorporate composting areas and organic practices.

Try AIGardenPlanner

Garden questions, answered

Common questions before you buy materials

Use these quick answers alongside the calculator so you can plan the right amount, avoid waste, and keep your garden project moving.

How much compost should I add to garden soil?
Many beds benefit from 1 to 2 inches of compost mixed into the top layer each season. Poor or sandy soil may need more organic matter over time.
Can I plant directly in pure compost?
Pure compost can be too rich and may hold too much moisture for many plants. Mix compost with soil or potting media so roots get a balanced growing environment.
When is the best time to spread compost?
Spring and fall are both good times to add compost. Spring feeds new growth, while fall lets compost mellow into the soil before the next growing season.