Carbon offsetting: How to calculate your carbon footprint when you travel

Whether at home or on a trip, your actions consume energy and create carbon emissions.

While you may already know that you can calculate your emissions for everyday activities, you might not realize that you can also calculate them for a specific trip or event.

To help you better understand the process, we've created this guide focusing on carbon emissions from travel. In addition to delving into the details of how to calculate your footprint for lodging and various modes of transportation, we'll take a closer look at what purchasing an offset entails, including which services are the most reputable.

How to calculate the carbon footprint of a trip

Tourism creates about 8% of the world's carbon emissions, according to Sustainable Travel International, a nonprofit organization that works with travelers, businesses and destinations to apply innovative conservation solutions to tourism.

You can calculate your emissions for both everyday life and trips using a carbon footprint calculator. For travel, these calculators consider the average carbon emissions of various travel types. Sustainable Travel International's calculator, for example, assumes that a passenger will emit 0.14 to 0.55 kilograms (0.31 to 1.21 pounds) of carbon emissions per kilometer (which equals a little more than half a mile) flown, depending on cabin class and flight distance.

But aircraft type and loads also play a role. For other types of transportation, fuel type is important, too. Some calculators even include emissions from vehicle manufacturing, which may increase based on the vehicle's age.

In short, different calculators will yield different results based on their underlying assumptions. As such, it's worth checking out several different options when figuring out your emissions.

For example, the Environmental Protection Agency has a carbon footprint calculator, but it unfortunately only calculates your footprint in three household areas: home energy, transportation and waste. So, although this calculator can help you determine your household's carbon emissions, it won't help you calculate your emissions from travel.

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If you want to calculate your annual household and travel emissions all at once, Conservation International, a nonprofit organization that focuses on finding solutions to environmental issues, has a carbon footprint calculator that you may want to try.

Conservation International's calculator also shows the math behind its results. So, you could use these numbers (admittedly based on energy use data from 2013 and 2015) to calculate your travel emissions separately from your household emissions.

The calculator assumes one night in an accommodation produces about 0.0383 metric tons of carbon emissions per occupied room. For passenger transport, it assumes the following:

• Flights less than 300 miles: 0.00025 metric tons of carbon emissions are produced per passenger mile.
• Flights of 300 to 2,299 miles: 0.00014 metric tons of carbon emissions are produced per passenger mile.
• Flights of 2,300 miles or more: 0.00017 metric tons of carbon emissions are produced per passenger mile.
• Intercity rail: 0.00014 metric tons of carbon emissions are produced per passenger mile.
• Commuter rail: 0.00017 metric tons of carbon emissions are produced per passenger mile.
• Subway, metro and trams: 0.00012 metric tons of carbon emissions are produced per passenger mile.
• Bus: 0.00006 metric tons of carbon emissions are produced per passenger mile.

Related: This travel company will plant trees for every flight and hotel room booked

Other calculators can help you determine your emissions from a specific flight in more detail.

For example, Atmosfair's calculator totals your flight emissions based on route, cabin and aircraft type. However, this calculator can be tedious to use if you have a lot of flights to offset, as it only lets you calculate one at a time.

If you're traveling by boat or car, you may want to use Sustainable Travel International's calculator since most other travel calculators don't specifically consider these modes of transportation. And if you want to calculate your carbon emissions based on miles flown, BlueSkyModel's air-mile model provides a simple calculation broken down by airline, aircraft and plane manufacturer.

There's also the Toitu Envirocare Household Calculator. This calculator's assumptions are based on average emissions in New Zealand, so the calculator will be most accurate when traveling in New Zealand. But you can use the calculator to estimate emissions from various lodging types, vehicles, public transport and flights in other places, too. As such, it may still be worth using when traveling outside New Zealand, especially if you tend to stay at less conventional lodging options.

Related: What your favorite airlines and hotels are doing to fight climate change

Which carbon footprint calculator should you use?

You should use the carbon footprint calculator or method that makes sense for your plans and that will be easiest for you to do the math with.

For example, Atmosfair's calculator is likely the most accurate for flights out of all the calculators discussed, but I use BlueSkyModel's air-mile model since it allows me to quickly determine my carbon emissions for all of the flights I take each year based on the mileage I've flown.

While I haven't tried offsetting carbon emissions from hotel stays, if I did, I'd likely use a calculator that walks me through the math used to determine its results, such as the one offered by Conservation International or the Toitu Envirocare Household Calculator.

After all, you don't have to calculate your carbon emissions exactly for your offset to make a difference.

How to offset your carbon footprint from traveling

Regardless of which carbon emissions calculator or calculation method you use, know that you don't have to buy carbon offsets through the calculator. You can opt to purchase carbon offsets via your chosen calculator, of course, but there are other options available, too.

Once I know the total amount of metric tons of carbon emissions that I want to offset, I like to buy them separately through an independent third-party organization that lists certified carbon offsetting projects that meet rigorous standards for monitoring, reporting, verification and certification. Abiding by these standards ensures the projects recommended are ones that will have the most impact once implemented.

Most offset programs create their own standards to define the requirements for projects within their program. However, there are some international standards to consider, such as the Verified Carbon Standard developed by the Climate Group and the International Emissions Trading Association.

Even after you find a standard that you like, it can be difficult to figure out how to support projects that follow that standard as an individual consumer. That's why I recommend turning to a third-party organization that lists certified projects that meet specific standards. Three highly regarded organizations that provide such listings are Gold Standard, Green-e and Climate Action Reserve.

You can browse carbon offsetting projects on each organization's website. However, Gold Standard makes it easy to donate to a particular project on their website, while Green-e and Climate Action Reserve refer you to individual projects.

Some airlines also allow you to offset carbon emissions from flights. Many only facilitate carbon offsetting when you purchase a ticket, while others will allow you to offset any flight (including on routes the airline doesn't operate). A few airlines, including British Airways and JetBlue Airways, even pay to offset at least some of their flights. So if you fly with an airline frequently, it may be worth looking into the carbon offsetting options available through your carrier.

While you can offset your carbon emissions after each flight, I like to do it in bulk for all of my flights at the end of each year. Once I've determined how many miles I flew, I'll buy carbon offsets through Gold Standard, which are coded as gifts and donations on my credit card statements.

But remember, not all carbon offsets are categorized this way by credit card companies. When I purchased lump sum carbon offsets through Cathay Pacific's Fly Greener program back in 2019, my purchase coded as airfare. So, be sure to factor where you're buying your carbon offsets into your payment strategy.

Related: How one travel platform enables travelers to book carbon offset trips

Reducing vs. offsetting emissions

Offsetting your carbon emissions from a trip is great, but reducing your carbon footprint is even better.

For example, consider traveling by train or bus instead of by plane for shorter distances. Traveling by intercity rail typically produces about half of a short-haul flight's carbon emissions per passenger mile, based on Conservation International's calculator. Buses are even more environmentally friendly, commonly generating just a quarter of a short-haul flight's carbon emissions per passenger mile, according to Conservation International's calculator.

Or, instead of taking a trip around the world, opt for a vacation close to home that requires less use of transportation.

You don't need to avoid long trips to be more environmentally conscious, though.

If flying to your destination, choose a nonstop route on a fuel-efficient aircraft. Once in your chosen location, pick a hybrid or electric rental car (instead of a regular vehicle) to get around.

Also consider staying at a hotel that's committed to sustainable practices — or, at the very least, keep your use of air conditioning in your hotel room to a minimum. You might even want to try eating vegan or vegetarian meals during your trip. After all, beef, lamb and mutton all have large carbon footprints compared to plant-based proteins due to the amount of cleared land required to raise them, methane they produce as they digest food and animal feed they consume, among other factors.

Related: How train travel can be good for the environment

Bottom line

When it comes to leisure travel, many travelers may find themselves hesitant to trade their dream vacation for a more environmentally friendly alternative.

While a trip to a nearby Caribbean country can be full of fun, few would argue it rivals a trip to the far-flung Maldives. Similarly, many would find it hard to bypass a comfortable business-class seat in favor of flying in the more eco-friendly economy cabin.

You don't have to feel guilty about enjoying that dream getaway in style, so long as you take a closer look at how you can lessen your impact on the environment. By offsetting your carbon emissions and considering other ways to reduce your carbon footprint when you travel, you can do your part to lessen the harm being done to our planet.

Think of the former as a tax you're choosing to pay to help offset the effects of your travels.