How is the footprint calculated?

Each source uses a rough factor: car km × 0.17 kg, flights × 0.25 t, monthly kWh × 12 × 0.4 kg, plus a yearly diet figure. They sum to a yearly total.

It's a rough estimate. Real factors vary by country, vehicle, energy grid, and flight type, so treat it as a guide.

What does 'trees to offset' mean?

How many mature trees, absorbing about 0.021 tonnes a year each, it would take to offset one year of your footprint.

Why does diet matter so much?

Food, especially meat and dairy, is a large share of personal emissions, so diet type noticeably shifts the total.

Does it include everything?

No. It covers the main sources — driving, flying, electricity, and diet — but not every activity. Real footprints include more.

Can I share a calculation?

Yes. Use Share to copy a link that reopens the calculator with the same figures.

Carbon footprint calculator

Enter your yearly car distance, flights, monthly electricity, and diet type. The calculator estimates your annual carbon footprint in tonnes of CO2, the monthly equivalent, and how many trees it would take to offset.

Use it to see roughly how your travel, energy, and diet add up to a yearly carbon footprint.

Annual footprint

6.14 t

Monthly footprint: 0.51 t
Trees to offset: 292

The result updates as you type. The headline is the annual footprint; the others show the monthly figure and the trees needed to offset a year.

How does it work?

Emission factors are rough global averages and vary by country, vehicle, and energy mix. Trees-to-offset uses about 0.021 t absorbed per mature tree per year. Use it for awareness, not precise accounting.

Carbon footprint estimate

\text{total} = \text{car} + \text{flights} + \text{electricity} + \text{diet}

car: Car km × 0.17 kg ÷ 1000.
flights: Flights × 0.25 t each.
electricity: Monthly kWh × 12 × 0.4 kg ÷ 1000.
diet: Yearly food footprint by diet type.

10,000 car km, 2 flights, 300 kWh/month, average diet: 1.7 + 0.5 + 1.44 + 2.5 ≈ 6.1 t a year.

Method & sources

Car: 0.17 kg CO2 per km. Flights: 0.25 t each. Electricity: 0.4 kg per kWh. Diet adds a yearly food footprint: meat-heavy 3.3 t down to vegan 1.5 t. Trees to offset use about 0.021 t absorbed per mature tree per year.

Sources

Where this method comes from — use these references to understand the formula, assumptions, and limits.

Greenhouse gas equivalencies calculator — U.S. Environmental Protection Agency, verified 2026-06-10
Calculate your carbon footprint — GOV.UK — UK Government, verified 2026-06-10

How we calculate

Car: 0.17 kg CO2 per km. Flights: 0.25 t each. Electricity: 0.4 kg per kWh.
Diet adds a yearly food footprint: meat-heavy 3.3 t down to vegan 1.5 t.
Trees to offset use about 0.021 t absorbed per mature tree per year.
Factors are rough global averages and vary by country and source.

Rounding

Tonnes are shown to two decimals and trees as whole numbers. The calculation uses full precision.

What this calculator does

Most personal emissions come from a few big sources: how much you drive and fly, your household electricity, and your diet. This calculator applies rough emission factors to each and adds them into a yearly total, then expresses it monthly and as trees to offset.

How to use it

Enter your car distance per year.
Enter how many flights you take a year.
Enter your monthly electricity use and pick a diet.
Read the annual footprint and trees to offset.

A worked example

10,000 car km, 2 flights, 300 kWh a month, and an average diet: 1.7 + 0.5 + 1.44 + 2.5 ≈ 6.1 tonnes a year — roughly 290 trees to offset.

Where the numbers come from

The factors are rough global averages: cars vary by fuel and efficiency, electricity by your grid's mix, and flights by distance and class. Use the result to compare choices, not as a precise audit.

Common mistakes

Entering monthly car distance in the yearly field.
Forgetting flights, which add up quickly.
Expecting precision from rough global factors.

When it's useful

Spotting your biggest emission sources, comparing lifestyle changes, or setting a personal reduction goal.

FAQ

How is the footprint calculated?: Each source uses a rough factor: car km × 0.17 kg, flights × 0.25 t, monthly kWh × 12 × 0.4 kg, plus a yearly diet figure. They sum to a yearly total.
How accurate is it?: It's a rough estimate. Real factors vary by country, vehicle, energy grid, and flight type, so treat it as a guide.
What does 'trees to offset' mean?: How many mature trees, absorbing about 0.021 tonnes a year each, it would take to offset one year of your footprint.
Why does diet matter so much?: Food, especially meat and dairy, is a large share of personal emissions, so diet type noticeably shifts the total.
Does it include everything?: No. It covers the main sources — driving, flying, electricity, and diet — but not every activity. Real footprints include more.
Can I share a calculation?: Yes. Use Share to copy a link that reopens the calculator with the same figures.

Related calculators

Embed this calculator

Add this calculator to your own site. The snippet includes the calculator iframe and a small attribution link:

<iframe src="https://wisecalcs.com/embed/en/carbon-footprint-calculator" width="100%" height="520" style="border:0" loading="lazy"></iframe>
<p>Calculator from <a href="https://wisecalcs.com/en/health/carbon-footprint-calculator">WiseCalcs</a></p>