Methodology
How CarbonCut turns your bills and records into emissions figures, every factor set it uses, and what we have and haven't checked. The same information is printed in the methodology section of every report.
The method
Emissions are activity multiplied by an emission factor: litres of diesel times kilograms of CO2-e per litre, kilowatt-hours times kilograms per kilowatt-hour. Scopes follow the GHG Protocol Corporate Standard. Scope 2 electricity is location-based.
CarbonCut stores your activity data as you entered it and calculates emissions when the dashboard or report is shown. Every figure in the report carries the factor it used, the factor's source and its vintage. When a new edition of a factor set is published, earlier years keep the factors they were reported under.
When CarbonCut reads a bill for you, a person confirms every figure against the original before it enters the baseline. The report states that activity data is as entered and has not been independently verified. For a group, the consolidated report uses operational control, taking 100 per cent of each entity.
What “audit-defensible” does and doesn't mean is set out in our plain-English definition.
Factor sets
| Category | Scope | Factor set | Checked |
|---|---|---|---|
| Electricity | Scope 2 (location-based) and scope 3 | National Greenhouse Accounts Factors 2025, Table 1, by grid region | Transcribed from the workbook; independent check in progress |
| Fleet fuel (diesel, petrol, LPG) | Scope 1 and scope 3 | National Greenhouse Accounts Factors 2025, Table 9, transport fuels | Checked against the workbook, 30 July 2026 |
| Natural gas | Scope 1 and scope 3 | National Greenhouse Accounts Factors 2025, by state, metro distribution | Checked against the workbook, 19 August 2026 |
| Business travel | Scope 3, category 6 | UK Government GHG conversion factors 2025 (DESNZ) | Transcribed from the workbook; independent check in progress |
| Employee commuting | Scope 3, category 7 | UK Government GHG conversion factors 2025 (DESNZ), including homeworking | Transcribed from the workbook; independent check in progress |
| Purchased goods and services (estimate) | Scope 3, category 1 | US EPA Supply Chain GHG Emission Factors v1.3, converted at the RBA FY2025–26 average AUD/USD rate | Transcribed from the dataset; independent check in progress |
| Waste to landfill | Scope 3, category 5 | National Greenhouse Accounts Factors 2025, Tables 15 and 16 | Transcribed from the workbook; independent check in progress |
Values for the checked factor sets, with worked examples, are on the emission factors pages.
Simplifications we disclose
- Natural gas scope 3 uses the metro distribution figure for each state. The workbook also publishes non-metro figures; the largest gap is under 7 per cent, on the scope 3 part only. The workbook publishes no gas scope 3 figure for Tasmania or the Northern Territory, so gas there is reported as scope 1 only.
- Western Australian electricity uses the South West Interconnected System factor, which covers Perth and the south-west, where nearly all WA businesses are connected.
- Business travel and commuting use UK government factors, because Australia publishes no equivalent set. The choices we make within them are printed in the report.
- Purchased goods and services are a spend-based estimate: dollars spent times an average factor for the category. It is labelled an estimate everywhere it appears, and physical data replaces it where you have it.
- Factors are rounded to two decimal places. Fuel factors are derived from the workbook's energy content and per-gigajoule factors, then rounded.