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Flight CO₂/CO2 Calculator (2025) — Per-Passenger by Distance, Class & RF

Free flight emissions calculator. Enter IATA airports to estimate kgCO₂e per passenger and round-trip totals using the UK Government’s 2025 conversion factors. Supports economy/premium/business/first, short vs long-haul, and Radiative Forcing (RF).

Type city or IATA (e.g., BER, JFK, LHR). Autocomplete included.
Accounts for non-CO₂ high-altitude effects.
Advanced (manual distance, airport overhead)
Great-circle distance is auto-calculated from airports if left empty.
Enter a per-passenger value, or check the box to treat it as a per-flight total to be split across passengers.
Open in Master Travel CO₂
Enter two airports (or a distance) and click Calculate.
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    🧭 Overview

    This Flight CO₂ Calculator estimates per-passenger kgCO₂e by combining great-circle distance, official UK Government 2025 aviation conversion factors, cabin class, and an optional Radiative Forcing (RF) setting for non-CO₂ high-altitude effects. Results can be shown for one-way or round-trip, with an optional per-flight overhead that can be split across passengers. Use the “Open in Master Travel CO₂” link for multi-leg itineraries and more modes.

    Factors source: UK Government — Greenhouse gas reporting: conversion factors 2025 (Business travel: air). Official collection: gov.uk/conversion-factors .

    ⚙️ How the calculator works

    • Distance: We compute great-circle (Haversine) distance from airport coordinates. You can override with a manual km value.
    • Route type: If both airports are in the UK → UK domestic. If either airport is in the UK → To/From UK with a short-haul (< 3,700 km) or long-haul (≥ 3,700 km) split. Otherwise → International (non-UK) proxy.
    • Emission factors: We use DEFRA/BEIS 2025 passenger-km factors by class. RF can be toggled; the chosen set already includes/excludes RF (we do not multiply by 1.9 again).
    • Cabin class mapping: Economy / Premium Economy / Business / First. Note: DEFRA 2025 provides no Premium/First for UK short-haul; in those cases we fall back to the published “average”.
    • Overhead (optional): Enter a kgCO₂e value per flight and tick “split across passengers”, or leave unticked to treat it as a per-passenger add-on per leg.

    🧮 Formula

    Per-passenger total (kgCO₂e) =
  (Distance_km × EF_class_route (kgCO₂e/pkm) + Overhead_per_passenger_per_leg) × Legs

Where:
  Distance_km       = great-circle distance between airports
  EF_class_route    = the single factor selected from DEFRA 2025, already "with RF" or "without RF"
  Overhead...       = 0 by default; if "per flight" is checked we split by passenger count
  Legs              = 1 (one-way) or 2 (round-trip)

    Note: Because EF already reflects the RF choice, do not add an extra ×1.9 outside the factor.

    🧪 Worked examples (match this tool exactly)

    Example A — BER → MAD (Berlin Brandenburg to Madrid Barajas)

    • Route type: International (non-UK)
    • Distance: ≈ 1,851 km (one way) using great-circle
    • Class & RF: Economy, RF on → non-UK economy factor 0.10849 kgCO₂e/pkm
    • One-way: 1,851 × 0.10849 = 200.8 kgCO₂e
    • Round-trip: 200.8 × 2 = 401.7 kgCO₂e → 0.40 tCO₂e
    Same route with RF off

    Economy “without RF” factor = 0.06463 kgCO₂e/pkm → round-trip ≈ 1,851 × 0.06463 × 2 = 239.3 kgCO₂e (≈ 0.24 tCO₂e).

    Example B — LHR → JFK (London Heathrow to New York JFK)

    • Route type: To/From UK, long-haul (≥ 3,700 km)
    • Distance: ≈ 5,540 km (one way)
    • Class & RF: Economy, RF on → UK long-haul economy factor 0.10916 kgCO₂e/pkm
    • Round-trip per passenger: 5,540 × 0.10916 × 2 = 1,209.5 kgCO₂e → 1.21 tCO₂e
    Business class comparison for LHR → JFK

    UK long-haul business (RF on) factor = 0.31191 kgCO₂e/pkm → 5,540 × 0.31191 × 2 = 3,456.0 kgCO₂e → 3.46 tCO₂e.

    ☁️ What is Radiative Forcing (RF)?

    Flying emits more than CO₂. At cruise altitude, aircraft produce NOₓ, water vapour, soot/particles and contrails/cirrus that trap heat. The combined warming beyond CO₂ is captured using an RF uplift. Many organisations use a multiplier of ×1.9. When you tick “Include RF”, we select the “with RF” factors directly from the 2025 tables.

    Diagram showing aviation climate impact: CO₂ plus non-CO₂ effects (contrails, NOx) forming total impact
    Non-CO₂ effects (contrails, NOₓ, cirrus) can roughly double climate impact vs CO₂ alone.
    Diagram showing aviation RF: Radioactive Forcing
    RF: Radioactive Forcing

    🧰 Common use cases

    • Travel footprint checks: compare flight options or classes before booking.
    • Corporate sustainability: quick per-trip estimates for internal reporting (note the factor year/class/route assumptions).
    • Education & research: demonstrate short- vs long-haul intensity and RF effects.
    • Content creators: embed results and share deep links for transparent “flight emissions” posts.

    ❓ Frequently asked questions

    Which emission factors are used?
    The tool uses the UK Government’s Greenhouse gas reporting: conversion factors 2025 for passenger air travel. We select a single per-passenger-km factor based on (a) whether the route is UK-domestic, to/from UK short- or long-haul, or international (non-UK proxy), (b) cabin class, and (c) your RF choice (with/without RF). We then multiply by distance and trip legs.
    What’s the difference between “with RF” and “without RF”?
    “With RF” includes the additional non-CO₂ warming from high-altitude emissions (contrails, NOₓ, cirrus), broadly approximated in the tables. “Without RF” shows CO₂e without that uplift. The two options pick different DEFRA factors — we do not apply an extra multiplier on top.
    Why do business and first class have higher emissions per passenger?
    Fewer seats per aircraft area and higher service levels mean more emissions are allocated to each passenger-km. DEFRA 2025 publishes separate factors by class (for long-haul UK and non-UK sets). For UK short-haul, Premium/First are not published; we fall back to the “average” factor.
    How accurate is the distance?
    We use great-circle distance from airport coordinates (OurAirports dataset). Actual routes, winds, holding patterns, and detours vary; this approach is standard for footprint calculators and generally sufficient for screening and comparisons.
    What does the “overhead per leg” option do?
    It lets you add a simple, fixed kgCO₂e per flight (e.g., taxiing, APUs, ground processes). Check the box to treat it as a per-flight total split across passengers, or leave unchecked to treat it as a per-passenger per-leg add-on. By default it’s 0 and not part of the published DEFRA factors.
    Do return flights simply double the emissions?
    Yes — we assume a symmetric return distance unless you override the distance manually or model separate legs in the Master Travel tool.
    Why do some routes use a “non-UK” factor?
    DEFRA/BEIS publishes a separate international (non-UK) proxy set by class. If neither airport is in the UK, we use that set. If either airport is in the UK, we use the UK short/long-haul tables as appropriate.
    Are the car/train comparisons exact?
    No. They’re rule-of-thumb using generic comparison factors to give scale. For formal inventory or policy work, use the relevant 2025 factors for each mode and geography.
    Can I share or export my result?
    Yes — use Copy, Export to TXT/PDF, Print, or Share Link (deep link carries your inputs and can auto-run).
    Does this include multi-leg itineraries or layovers?
    This thin page is a fast single-route calculator. For multi-leg trips, switching modes, or more detailed breakdowns, open the Master Travel CO₂ tool.

    📚 Sources & acknowledgements