This calculator turns four everyday habits into an annual CO2 figure: driving, flying, what you eat, and the electricity you use at home. Each one is converted with a simple emission factor, and the tool shows which category dominates. It is built for answering one practical question, "where would a change in my habits matter most?", not for producing a certified inventory. Below you can see exactly which factors are used, what is left out, and how to read the result without over-interpreting it.
The formula and the factors it uses
Every category is "amount of activity x emission factor". The numbers this page uses are:
- Driving: weekly km x 52 weeks x 0.192 kg CO2 per km
- Flying: one-way flights x 500 kg CO2 each, regardless of distance
- Electricity: monthly kWh x 12 months x 0.475 kg CO2 per kWh
- Diet: a fixed annual value taken from the table below
| Diet | Per year (kg CO2) | Per year (tonnes) |
|---|---|---|
| Meat-heavy diet | 2,500 | 2.5 |
| Average diet | 2,000 | 2.0 |
| Mostly vegetarian | 1,500 | 1.5 |
| Vegan (fully plant-based) | 1,000 | 1.0 |
These are this tool's own working assumptions, not official figures from any agency, and should be read as rough approximations. The driving factor is a simplified value for a typical petrol or diesel passenger car. The electricity factor is one fixed number, but real grids differ enormously: a grid rich in hydro, nuclear, or renewables produces far less CO2 per kWh than one that leans on coal. If you need the figure for your own country or supplier, look for the latest value published by your utility or by a public energy or environment agency and substitute it by hand.
Be careful when comparing with the global average
The comparison under your result uses roughly 4.7 tonnes of CO2 per person per year as a reference point. That figure is an approximate round value, and what it means depends on the year and on what is counted, for example whether land-use change is included. The more important point is that the two numbers are built differently. A national per-person figure divides a whole society's emissions, including power generation, industry, commerce, transport, and heating, by its population. Your four inputs cover only a slice of that. So a result below 4.7 tonnes does not mean you emit less than the average person; several large categories are not in the calculation at all.
Worked examples
| Profile | Inputs | Driving | Flights | Diet | Electricity | Total (kg) |
|---|---|---|---|---|---|---|
| City dweller, no car | 0 km/week, 0 flights, 200 kWh/month | 0 | 0 | 2,000 | 1,140 | 3,140 |
| Car commuter, a couple of trips a year | 100 km/week, 2 flights, 300 kWh/month | 998 | 1,000 | 2,000 | 1,710 | 5,708 |
| Long-distance driver, frequent flyer | 250 km/week, 8 flights, 400 kWh/month | 2,496 | 4,000 | 2,500 | 2,280 | 11,276 |
You can verify the second profile by hand: driving 100 x 52 x 0.192 = 998.4 kg, flights 2 x 500 = 1,000 kg, diet 2,000 kg, and electricity 300 x 12 x 0.475 = 1,710 kg, for a total of 5,708.4 kg, or about 5.7 tonnes. In that case electricity and diet together are over half of the total, and driving is roughly 17 percent. The third profile shows how one category can take over: eight one-way flights alone are 4,000 kg, more than a third of its 11,276 kg total. The first profile has no travel emissions, so only electricity and diet are left, adding up to 3,140 kg or about 3.1 tonnes.
Which changes make the biggest difference?
| Change | Reduction (kg CO2 per year) |
|---|---|
| Drive 10 km less per week | 100 |
| Drive 50 km less per week | 499 |
| Skip one one-way flight | 500 |
| Use 50 kWh less electricity per month | 285 |
| Move from an average to a mostly vegetarian diet | 500 |
| Move from a meat-heavy to an average diet | 500 |
Skipping one one-way flight (500 kg) is about as large as driving 50 km less every week (about 499 kg). Saving 50 kWh a month is only about 285 kg, which looks small, but it adds up when a whole household does it consistently. Weigh how easy each change is for you, not just its size. If you must travel, comparing public transport, car-sharing, or a lower-emission vehicle is a reasonable next step.
Common misunderstandings and limits of this tool
- It looks complete, but it is not. Home heating and cooking fuel, consumer goods, clothing, electronics, waste, and public services are not included. A real footprint is often larger than this estimate.
- 500 kg per flight is a flat average. In reality it depends on distance, seat class, aircraft, and how full the plane is. A short domestic hop and a long intercontinental flight get the same number here.
- No distinction between vehicle types. The driving factor assumes a conventional passenger car. An electric vehicle's emissions depend on the electricity used to charge it. For running costs, the Fuel Efficiency Calculator helps you see what you really consume.
- Household versus individual. Electricity use is a household figure, but the tool treats it as one person's. In a four-person home, entering roughly one quarter of the bill is a fairer approximation.
- The diet values are broad assumptions. What you actually eat, where it comes from, and how much is wasted can shift them a lot.
How to use the result
Pay more attention to the share of each category than to the absolute total. Pick the largest category, choose the easiest change within it, keep it up for three months, and recalculate. For electricity, enter the monthly kWh from your bill, and use the Electricity Cost Calculatorto see how much a saving is worth in money terms. If you need an official figure for a company, school, or report, use the accounting method required by the relevant authority. This tool's output is not suitable to cite.
Frequently Asked Questions
Is this an exact measurement of my real emissions?
No. It applies simple average factors, and several categories such as heating and consumer goods are missing, so treat the number as a reference rather than a measurement.
Why do flights have such a big impact on emissions?
A flight burns a lot of fuel in a short time. Because this tool counts each one-way flight as 500 kg, the number of flights alone can change your total dramatically even if your daily habits stay the same.
How do I enter a round trip?
The field counts one-way flights. A round trip is two flights, so two round trips means entering 4.
Can the result be converted into a number of trees?
How much a tree absorbs varies widely with species, age, and location, and it takes decades. Because such a conversion would be misleading, this tool does not offer one.
Is it a problem if I am above 4.7 tonnes?
The comparison is only a reference. National statistics include industry and power generation, while this tool covers four categories you enter yourself. What matters more is whether your own number goes down over time.
Related tools
- Fuel Efficiency Calculator - check the real consumption of your car
- Fuel Economy Unit Converter - switch between km/L, L/100 km, and mpg
- Electricity Cost Calculator - turn kWh into running costs