BuyCarbonOffsets.org
Guide

How to use our footprint calculator

6 February 2026·2 min read·Rajesh D ·Updated 1 June 2026

Our footprint calculator turns four inputs — flights, driving, home energy, and diet — into an annual estimate in tonnes of CO₂e, using emission factors from the UK Government (DESNZ), Ember, and Our World in Data. Flights and diet surprise people most. The result links straight to checkout with your tonnage pre-filled, so you can offset what you measured in about 90 seconds.

You can’t offset what you haven’t measured. Our calculator is built to give you a credible annual number in under a minute — here’s how to get the most accurate result, and the mistakes that throw people off.

What the calculator does

It turns four inputs — flights, driving, home energy, and diet — into an estimated annual footprint in tonnes of CO₂e. The factors behind it come from the UK Government (DESNZ) datasets, Ember, and Our World in Data, and we review them periodically. The result is a directional estimate: precise enough to offset against, without demanding a spreadsheet of receipts.

The four levers, in order of surprise

  • Flights — the input people most underestimate. A single long-haul return can outweigh a whole year of average driving. If you fly business or first, roughly double the per-seat figure, because each passenger occupies more of the aircraft.
  • Diet — a meat-heavy diet is roughly three times the footprint of a vegan one. It’s a bigger lever than most people expect.
  • Home energy — heating and electricity, strongly shaped by your country’s grid and how you heat your home.
  • Driving — annual distance and fuel type. Steady, predictable, and usually smaller than a couple of long flights.

A useful sanity check: the global average is about 4.7 tonnes per person per year, ranging from under 2 tonnes in many lower-income countries to 14+ tonnes in the US and Australia.

Common mistakes to avoid

  1. Underestimating flights — count every leg, and remember return trips are two legs.
  2. Forgetting premium cabins — business and first class carry a much larger per-seat footprint.
  3. Guessing home energy — check an annual bill if you can; estimates here drift easily.
  4. Businesses ignoring Scope 3 — in Business mode, the biggest error is leaving out Scope 3 (business travel and supply chain), which is usually the largest share of a company’s footprint.

Individuals vs business mode

Switch to Business mode for a directional Scope 1/2/3 estimate: Scope 1 (direct fuel and fleet), Scope 2 (purchased electricity), and Scope 3 (travel and supply chain). It’s ideal for a first-pass number; for audit-grade ESG reporting, our team builds a full inventory with you.

After you calculate

The result links straight to checkout with your tonnage pre-filled, so you can offset exactly what you measured in about 90 seconds. Measure first, reduce what you can, then retire verified credits for the rest — and keep the certificate as your record.

FREQUENTLY ASKED

How do I calculate my carbon footprint?

Enter four numbers — your annual flights, driving distance, home energy use, and diet type — and the calculator estimates your yearly CO₂e using published emission factors. It takes under a minute, and you can offset the result immediately with the tonnage pre-filled at checkout.

What is the average carbon footprint per person?

The global average is roughly 4.7 tonnes of CO₂e per person per year. It varies widely — under 2 tonnes in many lower-income countries, and 14 or more tonnes in the US and Australia. Use the average as a sanity check on your result, not a target.

Where do the emission factors come from?

From the UK Government (DESNZ) datasets, Ember’s grid-intensity data, and Our World in Data, reviewed periodically. The output is a directional estimate suitable for personal offsetting; for audit-grade business reporting we build a full inventory with you.

Why do flights have such a big impact?

Aviation is energy-intensive per kilometre, and the effect is concentrated in a few long trips. One long-haul return flight can emit more CO₂e than a full year of average car driving, and premium cabins roughly double the per-seat figure because each passenger occupies more of the plane.

Can I offset right after calculating?

Yes. The result links straight to checkout with your tonnage pre-filled, so the whole flow — measure, then retire verified credits — takes about 90 seconds.

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