Biogas Yield Calculator
Anaerobic digestion turns the organic, digestible portion of a feedstock into biogas, a mixture of methane and carbon dioxide. This calculator estimates the biogas volume from the feedstock mass, its volatile solids fraction, and the specific biogas yield per kilogram of volatile solids. It then applies the methane fraction to find the methane volume and multiplies by the calorific value of methane to estimate the recoverable energy. Because every one of these factors depends on the feedstock and the digester, each is a user-editable input rather than a fixed assumption, so the result reflects your own substrate and process rather than a generic average.
Biogas yield formula
Volatile solids = mass * VS fraction
Biogas volume = volatile solids * biogas yield per kg VS
Methane volume = biogas volume * methane fraction
Energy = methane volume * calorific value
The calorific value uses the lower heating value of methane, commonly about 9.94 kWh per cubic metre at standard conditions. Adjust it to match your reference temperature and pressure.
Anaerobic digestion context
- Only the volatile solids portion of a feedstock is digestible into biogas.
- Specific biogas yield varies widely by substrate; use a lab test or published figure for your feedstock.
- Methane fraction in raw biogas is commonly between about 0.5 and 0.7.
- Only the methane carries usable energy; the carbon dioxide is inert.
- Digester temperature, retention time, and loading rate all affect real-world yield.
Biogas yield: frequently asked questions
How is biogas yield calculated?
Biogas volume equals the feedstock mass times its volatile solids fraction times the specific biogas yield per kilogram of volatile solids. Volatile solids are the organic, digestible portion of the feedstock. Methane volume is the biogas volume times the methane fraction, and energy is methane volume times the calorific value of methane.
What are volatile solids?
Volatile solids (VS) are the fraction of the dry matter that burns off at high temperature, representing the organic material that microbes can digest. It is reported as a fraction of fresh mass or of total solids. Because it varies by feedstock, this calculator takes the volatile solids fraction as a user-editable input.
What biogas yield per kg of volatile solids should I use?
Specific biogas yield depends strongly on the feedstock and digestion conditions, so it is an input you supply, typically expressed in cubic metres of biogas per kilogram of volatile solids. Use a value from a lab test or a published reference for your specific substrate.
What methane fraction does biogas contain?
Raw biogas is a mixture of mainly methane and carbon dioxide. The methane fraction is commonly between about 0.5 and 0.7 depending on feedstock and process, and you enter it directly. Only the methane carries the usable energy.
How is the energy content found?
Energy equals the methane volume times the calorific value of methane. The lower heating value of methane is commonly taken as about 9.94 kilowatt-hours per cubic metre at standard conditions, which you can adjust as an input to match your reference conditions.
Official sources
- U.S. Environmental Protection Agency: Anaerobic Digestion.
- U.S. Environmental Protection Agency: AgSTAR Program.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.