Free tool
Enter a departure and destination airport to estimate the carbon footprint of a flight, calculated with UK Government (DESNZ) conversion factors — then offset it in a few clicks.
Choose a departure and destination airport
Emissions are calculated from the great-circle distance between the two airports using UK Government (DESNZ) conversion factors — no region or aircraft selection required.
The tool is deliberately simple to use and fully traceable underneath. Two airports are enough, because the haul band that drives the emissions factor follows from the distance between them and whether the route stays inside one country.
Emissions factors come from the Greenhouse gas reporting: conversion factors 2026, published by the UK Department for Energy Security and Net Zero (DESNZ/DEFRA) on 11 June 2026 — the reference set used for UK statutory carbon reporting and widely accepted for voluntary disclosure.
Results use DEFRA's with-RF factor set by default, capturing the additional warming effect of emissions released at altitude. DEFRA publishes with-RF and without-RF factors as separate sets; you can switch to combustion-only in the methodology panel.
Great-circle distance is uplifted by 8% per DEFRA methodology to account for indirect routing, holding patterns and taxiing. DEFRA's published factors exclude this uplift, so it has to be applied to the distance.
Short same-country flights use DEFRA's domestic factor, which is around 82% higher per kilometre than short-haul international — short sectors are dominated by taxiing, take-off and climb, and flown by smaller regional aircraft. Longer routes fall into the short-haul or long-haul band by distance.
Every result shows the exact coefficient applied, the haul band it came from, and whether that coefficient is a published DEFRA value or a labelled derivation — so any figure can be traced back to source.
Figures are estimates for a single passenger and cover the flight itself (tank-to-wake), excluding upstream fuel production and airport operations. For a formal inventory, reconcile the factor basis with your reporting framework — or talk to our carbon accounting team.
This tool is one example of the carbon accounting integrations we build for partners — lightweight to embed, backed by recognized emissions coefficients, and connected to real-time offsetting through the Carbonmark API.