What it does
The GHG Protocol is the most widely used way for organisations to count their greenhouse gas emissions. It sorts them into three scopes:
- Scope 1: direct emissions from things the organisation owns or controls, such as gas boilers, company vans and refrigerant that leaks from air conditioning.
- Scope 2: emissions from making the electricity, heat, steam and cooling it buys. They are reported two ways: location-based, with the average factor of the grid where the energy is used, and market-based, with the factor of the supply actually contracted (a green tariff, a certificate, or else the residual mix).
- Scope 3: all other indirect emissions in the value chain, in 15 categories, such as purchased goods (1), waste (5), business travel (6) and employee commuting (7).
This page does the inventory arithmetic for a small business. Each activity row is amount × factor = kg CO₂e; for a refrigerant leak, the factor is the gas’s global warming potential (GWP). It adds the rows up by year, scope and category, shows both Scope 2 totals, works out intensity (tonnes per employee and per million of revenue) and the change from the year before, and gives CSV and report downloads.
No factors are built in. Use the ones from your country’s official sources, your supplier and the GWP values your rules name.
How to use it
- Paste or type the rows: year, type, description, amount, unit, factor, market factor. Open a file reads a CSV, TSV or Excel sheet; Add a row with a form builds one row at a time and explains each type. The type is a short id such as
electricity,refrigerantorcommuting(see Types, scopes and categories). - For electricity and purchased heat, add a market factor if you have one. Left empty, the location factor is used in the market-based total and the page notes it.
- Type employees and revenue for each year for the intensity lines.
- Choose whether the headline total uses market- or location-based Scope 2.
- Download the rows with their results, the summary table, or the report.
Worked example
The made-up example is a small workshop with 12 staff in 2024 and 13 in 2025:
- 2024, Scope 1: 60,000 kWh gas × 0.2 + 5,000 L diesel × 2.7 + 2 kg refrigerant × GWP 2,000 = 29.50 t.
- 2024, Scope 2: 80,000 kWh × 0.4 = 32.00 t location-based; × 0.45 (a supplier factor) = 36.00 t market-based.
- 2024, Scope 3: goods 45.00 t + waste 4.00 t + flights 6.00 t + commuting 14.40 t = 69.40 t.
- 2024 total, market-based: 134.90 t, or 11.24 t per employee and 67.45 t per million of revenue.
- In 2025 the business moved to a green tariff (market factor 0.05): Scope 2 market-based falls to 3.80 t and the total to 99.12 t, −26.5 %. Location-based, the fall is only 5.1 %, because the grid itself changed little.
Tips
- Report both Scope 2 figures; they answer different questions.
- Spend-based Scope 3 (money × factor) is a rough start. Replace the largest lines with supplier or activity data over time.
- Keep the same factor sources between years, or recalculate the earlier year, so the change reflects what you did rather than new factors.
FAQ
Is this a certified carbon calculator? No. It follows the GHG Protocol’s structure for learning and internal planning. A formal inventory sets boundaries, a base year, data quality checks and may need third-party verification.
Which GWP should I use? The one your reporting scheme names, usually from a specific IPCC assessment report. Type it as the factor of the refrigerant row.
Why does the market-based total need a residual-mix factor? Without contracts, the energy you buy is the part of the grid nobody claimed, which is usually more carbon-intensive than the grid average. Using the plain grid average would double count the green power others bought.
Where the numbers come from
- Structure and scope definitions after the GHG Protocol Corporate Accounting and Reporting Standard (WRI/WBCSD, revised 2004), the GHG Protocol Scope 2 Guidance (2015) and the Corporate Value Chain (Scope 3) Standard (2011). The page uses the general definitions and category names only.
- No emission factors or GWP tables are built in. The example company and every number in it are made up, with rounded factors chosen only to show the sums.
- Arithmetic written by fibub and checked against pandas.
Standard scientific values, such as constants, atomic weights and melting points, are facts found in every textbook; we name where ours were checked. If you are an author or publisher and want a value, a credit or a table changed or removed, tell us and we will act quickly.
Last updated 2026-11-09.