Short answer: burning one litre of diesel releases about 2.687 kg CO2e, and one litre of petrol about 2.331 kg CO2e. These are the factors we use for company vehicles in Singapore, built from the National Environment Agency's GHG Measurement & Reporting Guidelines (Appendix to Part II, Version 3). Multiply the litres in your fuel records by these numbers to get your Scope 1 emissions in kg CO2e.
Why "per litre", and where the number comes from
Your fuel-card statements and receipts show litres, so a per-litre factor lets you go straight from your records to emissions. NEA publishes its fuel factors per tonne of fuel and per unit of energy, not per litre, so we convert them in three steps:
- Energy in the fuel. NEA gives the energy content per tonne (diesel: 43 GJ per tonne).
- Litres to tonnes. We use published average fuel densities from the UK government's 2025 greenhouse gas conversion factors, since no Singapore figure is published. A litre of diesel works out at about 35.7 MJ of energy.
- CO2 per unit of energy. NEA's factor (diesel: 74.1 kg CO2 per GJ) gives the CO2.
For diesel, that comes to about 2.646 kg of CO2 per litre. We then add the small amounts of methane and nitrous oxide that vehicle engines also release, taken from the 2006 IPCC Guidelines for road transport. That adds about 0.041 kg, giving 2.687.
CO2e ("CO2 equivalent") puts those other gases on the same scale as CO2, using the multipliers set in Singapore's Carbon Pricing Act 2018 (28 for methane, 265 for nitrous oxide).
Two assumptions sit behind both factors: all diesel and petrol is treated as ordinary mineral fuel with no biofuel blend, and the factors cover burning the fuel only, not producing or transporting it. The petrol factor uses the IPCC values for light-duty petrol vehicles from 1995 onwards, which covers typical vans and cars. The full working is on How we calculate.
How to work it out, step by step
- Confirm the reporting period, for example calendar year 2025 or your financial year.
- Collect your fuel records for every company vehicle: fuel-card statements, pump receipts or supplier invoices.
- Read the litres, not the dollars. Every statement or receipt shows the quantity pumped.
- Keep diesel and petrol separate and add up the litres of each for the period.
- Multiply total diesel litres by 2.687 and total petrol litres by 2.331. The answers are in kg CO2e.
- Add the two together and divide by 1,000 to get tonnes CO2e.
A worked example
These are example inputs, not a real company's data.
A small firm runs two diesel lorries and one petrol van. Its fuel-card statements for 2025 show:
| Vehicle | Fuel | Litres (2025) |
|---|---|---|
| Lorry 1 | Diesel | 9,840 |
| Lorry 2 | Diesel | 7,320 |
| Van | Petrol | 2,460 |
- Diesel: 17,160 litres × 2.687 = 46,108.92 kg CO2e
- Petrol: 2,460 litres × 2.331 = 5,734.26 kg CO2e
- Total: 51,843.18 kg ÷ 1,000 = about 51.84 tonnes CO2e
That's this firm's Scope 1 from vehicles for 2025. When you report it, state the factors you used and where they came from, so your customer can check the working.
Common mistakes, and how to avoid them
- Using dollars instead of litres. Pump prices change all the time, so a dollar amount can't be turned into emissions reliably. Always work from litres.
- Mixing diesel and petrol. They have different factors. Adding the litres together and using one factor gives the wrong answer.
- Counting vehicles you don't own or control. As general guidance, the GHG Protocol puts emissions from sources your company owns or controls in your Scope 1. A hired lorry that comes with its own driver is usually its owner's Scope 1, not yours. Leased vehicles depend on how your company sets its reporting boundary, so pick an approach, apply it consistently and say which you used. If your customer has a rule, follow it.
- Including staff's personal cars. Fuel or mileage claims for an employee's own car are generally not your Scope 1, because the company doesn't own or control the car. The GHG Protocol treats business travel in vehicles the company doesn't own as Scope 3.
- Forgetting LPG. If you run LPG forklifts or other LPG equipment on site, that fuel is Scope 1 too. Our factor for LPG burned in equipment is 1.583 kg CO2e per litre.
Electricity is the other half
Fuel is Scope 1. The electricity you buy is Scope 2, worked out with a different factor: Singapore's grid emission factor and how to use it. New to the scopes? Start with Scope 1 vs Scope 2 emissions, in plain English.
If you'd rather not do it yourself
Uncle ESG does this for you. Send your fuel records and electricity bills, and a person compiles a GHG Protocol-aligned Scope 1 & 2 report, with every factor cited to its source.
- Standard: S$150, 5 business days.
- Priority: S$300, 48 hours, firm.
- Multi-Site: S$250 for the first site plus S$90 per additional site, 7–14 days.
Fixed price, paid upfront. Turnaround counts from a complete submission, once we have your full details and bills, not from the moment you pay. Get started.
Sources
- GHG Measurement & Reporting Guidelines, Appendix to Part II (Version 3), Table 3, National Environment Agency.
- 2006 IPCC Guidelines, Volume 2, Chapter 3 (Mobile Combustion), Table 3.2.2, Intergovernmental Panel on Climate Change.
- Carbon Pricing Act 2018, First Schedule, Singapore Attorney-General's Chambers (Singapore Statutes Online).
- Greenhouse gas reporting: conversion factors 2025, UK Department for Energy Security and Net Zero (fuel densities).
- GHG Protocol Corporate Standard, World Resources Institute and WBCSD.