How to Calculate Your Company's GHG Emissions — A Beginner's Guide

Who this is for

Someone who understands what Scope 1 and Scope 2 mean (see our Scope 1, 2 & 3 guide) and now needs to actually produce a number for a report or questionnaire.

Plain explanation

Almost every emissions calculation follows the same shape:

Activity data (how much of something you used) × Emission factor (how much CO2-equivalent that activity produces) = Emissions

You are very unlikely to need to measure emissions directly with a sensor. Instead, you take a number you probably already have — litres of fuel purchased, kWh of electricity billed — and multiply it by a standard, published emission factor for that fuel or electricity source.

India specifics — step by step

Step 1: Gather your activity data.

• For Scope 1: annual fuel consumption for each source (diesel generators, company vehicles, LPG/furnace fuel), in litres or kg. Pull this from purchase records or fuel supplier invoices, not estimates.
• For Scope 2: annual electricity consumption in kWh, from your electricity bills. If you have multiple sites, gather this per site and add them up.

Step 2: Find the right emission factor.

• For diesel: a commonly used factor is roughly 2.68 kg CO2 per litre (from standard GHG Protocol / IPCC-based fuel tables).
• For petrol: roughly 2.31 kg CO2 per litre.
• For grid electricity in India: use the Central Electricity Authority's (CEA) CO2 Baseline Database figure for the current financial year — 0.710 tCO2/MWh for FY 2024–25 (provisional; check for the latest published version before you calculate).
• Always note which version/year of the emission factor you used — assessors will ask, and factors change annually.

Step 3: Do the multiplication.

• Scope 1 (diesel example): litres of diesel × 2.68 kg CO2/litre = kg CO2, then divide by 1,000 for tonnes.
• Scope 2 (electricity example): MWh consumed × CEA factor (tCO2/MWh) = tonnes CO2.

Step 4: Add up multiple sources. If you have more than one fuel type or more than one site, calculate each separately, then sum them for your total Scope 1 (all fuel sources combined) and total Scope 2 (all electricity combined).

Step 5: Sanity-check the result. A mid-sized factory's Scope 2 emissions from grid electricity are very often larger than its Scope 1 emissions from on-site fuel — if your numbers show the opposite by a wide margin, double-check your units (kWh vs. MWh is a common error — 1 MWh = 1,000 kWh).

Worked example

A small textile unit in Tiruppur wants its Scope 1 and Scope 2 numbers:

• Diesel generator: 2,000 litres/year × 2.68 kg CO2/litre = 5,360 kg CO2 = 5.36 tonnes CO2 (Scope 1).
• Grid electricity: 300,000 kWh/year = 300 MWh × 0.710 tCO2/MWh = 213 tonnes CO2 (Scope 2).
• Total (Scope 1 + 2): 5.36 + 213 = 218.36 tonnes CO2e for the year.

This unit now has two real, defensible numbers it can enter into a BRSR Core disclosure or a customer questionnaire, with a clear note of the emission factors and year used.

Checklist

• Pull actual fuel and electricity data from invoices/bills — never estimate from memory.
• Confirm units before multiplying — litres vs. kilolitres, kWh vs. MWh are the most common mistakes.
• Use the current financial year's CEA grid emission factor for Scope 2, not an old one.
• Record your source and version for every emission factor you use.
• Add up all fuel sources for Scope 1 and all electricity sources for Scope 2 before reporting a single total.
• Keep your raw activity data (bills, invoices) on file — an assessor will want to trace the number back to its source.

What to do next

If you haven't already, make sure you're clear on what Scope 1, 2, and 3 actually mean before running these calculations.

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Current as of: 22 July 2026. Fuel emission factors are broadly stable; the CEA grid emission factor is revised annually — always confirm the current year's published figure before calculating Scope 2.

Sources:

• GHG Protocol — Scope 3 FAQ
• CEA — CO2 Baseline Database for the Indian Power Sector, User Guide v21.0