Both calculators carry the word “compost,” but they answer different halves of the home-composting question. The compost calculator is a purchase tool: how much finished compost to order for a garden, lawn, or raised bed. The composting impact calculator is a scenario worksheet: what a year of composting food scraps might avoid in emissions and produce as compost. One helps you apply the product; the other helps you estimate the benefit of making it.
What each calculator does
The compost calculator estimates compost volume, cubic yards, bag count, bulk cost, weight, and practical application depth for gardens, lawns, and raised beds. Volume is area times depth; the waste allowance is applied once before dividing by the entered bag yield and rounding up to whole bags. The calculator does not assume a universal density or price — bag yield, density, moisture, settling, and delivered volume vary, so you enter package or supplier values such as bag volume and the optional bag price, bulk price, or bulk density. Weight and cost appear only when their assumptions are entered.
The composting impact calculator multiplies food-waste mass by factors you enter. The avoided-emissions scenario is waste mass times an entered emissions factor, and the compost-yield scenario is waste mass times an entered yield factor — for 100 kg of food waste with factors of 0.20 kg CO2e per kg and 0.50 kg per kg, the results are 20.0 kg CO2e and 50.0 kg. The calculator supplies no emissions or yield factors itself: all factors are scenario values entered by you, with their source or measurement basis recorded beside the inputs. The result is a sensitivity range for the factors you enter, not a confidence interval, and the page notes it is not for inventories, certifications, offsets, or compliance filings.
Side-by-side
| Compost calculator | Composting impact calculator | |
|---|---|---|
| Domain | Construction & Home | Ecology |
| Question | How much finished compost do I order for an area? | What is the impact of composting food waste? |
| Inputs | Area dimensions, depth, bag yield, waste allowance, optional price or density | Waste mass, entered emissions factor, entered yield factor, provenance |
| Primary output | Volume, cubic yards, whole bags, cost, weight | Avoided CO2e and compost yield in kilograms |
| Formula | Volume = area × depth; waste applied once; bags rounded up | Waste mass × entered factor per scenario |
| Factor policy | No assumed density or price; user enters values | No supplied emission or yield factors; user enters all |
When to use which
Use the compost calculator when you are spreading or ordering: measure the garden or raised-bed area, choose an application depth, enter the bag or bulk values from your supplier, and read the cubic yards or whole bags to buy. Its companion tools are the mulch and topsoil calculators for other landscape materials and the square footage calculator for measuring the area first.
Use the composting impact calculator when you want a directional picture of your food-waste diversion: enter the mass you compost and the factors from a named dataset, record the method, geography, year, and boundary, and compare scenarios — for example, food waste composted versus landfilled, using the landfill-gas context behind the avoided-emissions idea. If both questions apply to you — you compost scraps at home and also buy compost for the garden — run both calculators, but keep their results separate: cubic yards and bags are purchase quantities, while kilograms of CO2e are scenario estimates.
Limits and disclaimer
Both calculators are educational estimates. The compost calculator depends entirely on entered assumptions: bag yield, density, moisture, settling, and delivered volume vary, and displayed precision should not be mistaken for measurement accuracy. The composting impact calculator’s range reflects sensitivity to the factors you enter, not a confidence interval, and it supplies no landfill, water, tree, or universal-benefit equivalent — a finite arithmetic result does not establish code compliance, certification, or model validity. Neither tool replaces a supplier quote, a versioned emissions dataset, or professional guidance.