What is an emission factor, and how does a bill turn into a carbon number?
An emission factor is a ready-made multiplier: kilograms of carbon dioxide for each unit you buy, such as a litre of diesel or a kilowatt hour (kWh) of power. Multiply the quantity on your bill by it. Example: 100 kWh x 0.675 = 67.5 kilograms (kg).
A shopping bill and a carbon bill
At the market, quantity times price per kilo gives what you pay. The carbon version has the same shape: quantity times emission factor gives the kilograms of carbon dioxide (CO2).
The Greenhouse Gas (GHG) Protocol's words: activity data is a measure of a level of activity that results in emissions, such as kilowatt hours of electricity used or quantity of fuel used. An emission factor is a factor that converts activity data into emissions data, for example kilograms of carbon dioxide equivalent (CO2e) emitted per litre of fuel consumed. CO2e is the unit that folds other gases into one number.
What to read off each bill
- Electricity bill: the kWh used in the month. If your bill shows kilovolt-ampere hours (kVAh), that is not kWh.
- Diesel invoice: litres. If it shows kilograms, convert first.
- Cooking gas: the kilograms of liquefied petroleum gas (LPG) in the cylinders bought.
Which factor to pick
The Corporate Standard, the main GHG Protocol rulebook for company footprints, says that for most small to medium-sized companies, Scope 1 is calculated from the purchased quantities of commercial fuels using published emission factors, and Scope 2 mainly from metered electricity consumption and a supplier-specific, local grid or other published factor. It adds that where source- or facility-specific factors are available, they are preferable to generic ones.
Senseible's factors now: electricity 0.675 kg of CO2 per kWh for financial year (FY) 2025-26 (0.710 for FY 2024-25), diesel 2.645 kg per litre, LPG 2.98 kg per kilogram. Use the factor for the year of the bill.
The one mistake that ruins it
Matching units. A factor per litre applied to kilograms of fuel gives a wrong answer, with no warning. Check the unit on the bill against the unit the factor is for.
Example: three bills, one month
- Electricity: 1,200 kWh x 0.675 = 810 kg CO2 (Scope 2)
- Diesel for a generator: 150 litres x 2.645 = 396.75 kg CO2 (Scope 1)
- LPG: 2 cylinders of 19 kg = 38 kg x 2.98 = 113.24 kg CO2 (Scope 1)
- Total: 810 + 396.75 + 113.24 = 1,319.99 kg, about 1.32 tonnes. Scope 1 is about 510 kg (509.99), Scope 2 is 810 kg.
Example quantities. Your bills will differ.
What Senseible does here
Senseible reads fuel invoices and electricity bills into records, so the quantities behind each figure are on file. It applies the factor for the bill's financial year and shows the quantity next to the result. It cannot fix a bill that is unreadable or missing.
- Can I calculate my footprint from purchase invoices?
- My electricity bill is in kVAh. How do I calculate?
- India's grid emission factor for FY 2025-26
- Free calculators
Sources: GHG Protocol Corporate Value Chain (Scope 3) Standard (Chapter 5 and glossary), GHG Protocol Corporate Accounting and Reporting Standard, revised edition (Chapter 4, scopes and double counting), IPCC 2006 Guidelines, Volume 2 Energy, Chapter 1 (Tables 1.2 to 1.4), CEA CO2 Baseline Database, version 22.0
Last reviewed 2026-11-07. Definitions are from the Scope 3 Standard glossary; the small-company method is from Corporate Standard Chapter 6. Factors are the figures Senseible uses now (IPCC 2006 defaults for fuels, CEA version 22.0 for the grid). Re-check when either is revised.