Most of us can rattle off the calorie count of a flat white before we can name the carbon cost of a weekend in Lisbon. That feels backwards, given which one is actually heating the planet. The good news: working out the rough footprint of a trip isn't hard maths, and you don't need a climate science degree to do it. You need a flight number, a hotel address, a sense of how you'll get around, and about ten minutes. Here's how to actually do it — what to measure, what to ignore, and what to do with the number once you have it.
Why "rough" beats "perfect"
Carbon accounting for individual trips is genuinely fuzzy. Different calculators will give you different answers for the same flight, sometimes wildly so, because they make different assumptions about aircraft type, load factor, the warming effect of contrails, and whether to count the fuel burned getting your suitcase to the cargo hold. Don't let the imprecision put you off. A footprint that's directionally right — say, "this trip is around a tonne of CO₂" — is enough to make smarter choices. Chasing three decimal places is a procrastination tactic.
The goal isn't a perfect number. It's a number you trust enough to compare. Trip A versus Trip B. Train versus plane. Long-haul fortnight versus two short-haul weekends. That's what a trip footprint calculator is actually for.
The four things that matter
For almost any trip, your footprint breaks down into four buckets. Get these roughly right and you've captured the vast majority of the impact:
- Getting there and back. Usually the biggest single line item, especially if you're flying.
- Where you sleep. Hotels burn energy heating, cooling, lighting, laundering and feeding you.
- How you move around once you're there. Taxis, trains, scooters, that rental car you swore you wouldn't get.
- What you eat, drink and buy. Less obvious, but it adds up — particularly food.
Most people obsess over the flight and ignore the other three. That's understandable — flights are concentrated, dramatic emissions — but it can lead to weird outcomes, like skipping a short-haul trip and then driving a petrol SUV around a national park for two weeks instead.
Step one: the journey
Start with the leg that gets you to your destination. The simplest approach is to use a reputable online calculator — the ones run by environmental NGOs or national agencies tend to be conservative and transparent about their methodology. Plug in your departure airport, arrival airport, cabin class and whether it's return.
A few things to know:
- Cabin class matters a lot. Business class roughly doubles or triples your share of the plane's emissions compared with economy, because you take up more space. First class is worse again.
- Direct beats connecting. Take-off and landing are fuel-intensive. A non-stop flight is almost always lower-carbon than two shorter hops covering the same distance.
- Contrails count. The non-CO₂ warming effect of aviation — contrails, water vapour, nitrogen oxides at altitude — is significant. Good calculators apply a "radiative forcing" multiplier, often around 1.7 to 2x, to reflect this. If your calculator gives you a CO₂-only figure, mentally double it for the actual climate impact.
For trains, buses and cars, distance multiplied by a per-kilometre factor will get you close. As a rough order of magnitude per passenger-kilometre: trains are usually low, coaches similarly so, a full car middling, an empty car driven solo significantly worse. A short-haul flight per passenger-kilometre tends to be the highest of the lot.
Step two: the hotel
This is where most travellers wave their hands. Don't. Accommodation is often the second-largest chunk of a trip's footprint, especially on longer stays.
The crude method: multiply the number of nights by an average per-room emissions figure. Industry-reported averages tend to land somewhere in the range of 10 to 30 kg of CO₂ per room per night, depending on the country, the star rating and how the hotel is powered. Luxury properties with pools, spas and round-the-clock air-conditioning sit at the higher end. A small guesthouse in a cool climate sits at the lower end.
The better method: look for hotels that publish their actual carbon intensity per room-night, or that hold a recognised sustainability certification. Certifications worth knowing about include Green Key, EarthCheck, LEED, BREEAM and the GSTC-recognised standards. None of them are perfect, but a certified property has at least had to demonstrate something to a third party — which beats a vague "eco" claim on the homepage.
Things that actually move the needle on a hotel's footprint:
- Source of electricity (renewable versus grid versus on-site fossil generation).
- Heating and cooling system efficiency.
- Whether they treat and reuse water.
- Food sourcing in the restaurant.
- Whether single-use plastics have actually been removed or just rebranded.
Step three: getting around
Once you've landed, the daily transport choices stack up faster than people realise. Two weeks of daily taxis in a big city can rival a short-haul return flight. A rented petrol car driven 200 km a day for a fortnight can rival a medium-haul one.
To estimate this, sketch your itinerary in advance. How many kilometres a day, by what mode? Apply rough per-kilometre factors:
- Walking and cycling: effectively zero. Plan for these wherever feasible.
- Metro, tram, bus: low, especially in cities with electrified, renewable-heavy grids.
- Taxi or rideshare: middling to high, depending on the vehicle. An electric taxi on a clean grid is genuinely low-carbon. A diesel one in heavy traffic is not.
- Rental car: depends entirely on the car. A small hybrid driven sensibly is fine. A large SUV is not.
- Domestic flights: almost always the worst option per kilometre. If a train exists and takes under six hours, take the train.
Step four: food, drink and stuff
This is the bucket people forget. A rough rule: assume around 2 to 3 kg of CO₂ per person per day for an average omnivorous diet, lower for plant-based, higher if you're eating beef daily. Over a two-week trip, that's a non-trivial number — comparable to a short flight on its own.
Souvenirs and shopping are harder to pin down because the embedded carbon of a product depends on what it's made of, where, and how it got to you. The honest approach is to buy less, choose local where local actually means local, and prefer durable goods over disposable ones. A linen shirt you'll wear for a decade is a better climate decision than a fast-fashion haul, full stop.
Putting it all together
Add the four buckets. You'll end up with a single number — likely somewhere between a few hundred kilograms for a domestic weekend by train and several tonnes for a long-haul fortnight in business class. Write it down. The act of writing it down is doing most of the work, because next time you're planning a trip, you'll have a reference point.
Useful comparisons to keep in your head:
- The average global per-person carbon budget consistent with limiting warming to 1.5°C is roughly two tonnes of CO₂ per year, total — covering everything you do, not just travel.
- A single long-haul return flight in economy can use a year's worth of that budget on its own.
- A week in a well-run, renewables-powered hotel might add tens of kilograms; a week in a poorly run one might add several times that.
None of this is a guilt trip. It's a planning tool. Once you can see the shape of a trip's footprint, you can start making real trade-offs: fewer, longer trips instead of constant short hops; trains where they exist; certified hotels over default ones; cities you can walk over cities that demand a car.
What to do with the number
First, reduce what you can. The hierarchy is always avoid, then reduce, then offset — in that order. Skipping the unnecessary connection flight is worth more than offsetting it after the fact.
Second, for what's left, look for offsets that are actually verifiable. The voluntary carbon market has a chequered history, and the difference between a credible offset and a worthless one is enormous. Look for projects with third-party verification, registries you can search, and ideally on-chain or otherwise tamper-evident records so the same tonne isn't being sold twice.
Third, build the habit. The travellers who actually shrink their footprints aren't the ones who do one big calculation and post about it. They're the ones who run the numbers casually, every trip, and let the comparison shape next year's plans.
Where IMPT fits in
If running these numbers manually sounds like more admin than you're going to do, the IMPT platform takes a chunk of it off your hands. Booking a hotel through IMPT offsets one tonne of CO₂ on-chain — paid by us out of our commission, not bolted on to your bill — across our 1.7 million properties in 195 countries. The IMPT shop, the IMPT Card and the IMPT Token extend the same idea to everyday spending, so the work of decarbonising a lifestyle isn't all loaded onto the trip-planning stage. Calculate first, choose well, and let the platform handle the offset paperwork in the background.