Methodology
How the CO₂ counter works
Every number on this site is an estimate built from published annual data. Here is exactly what each one means, how it is calculated and how far you can trust it.
What each number means
| Number on the site | What it shows |
|---|---|
| CO₂ emitted worldwide this year | Estimated global emissions from 1 January (your local time) until now, at the 2025 annual rate. |
| Since you opened this page | The same rate, counted from the moment the page loaded. It keeps counting while paused. |
| 1.5 °C carbon budget left | 170 Gt minus the CO₂ emitted since 1 January 2026 at 42.2 Gt a year. |
| Runs out in | The time left until that budget reaches zero if emissions stay at today’s level. |
| Country counters | Each country’s fossil and industry CO₂ for the latest complete year (2024), spread evenly over the year. |
You can explore all of these on the live counter and the CO₂ emissions by country ranking.
The formulas
The counters use simple arithmetic so anyone can check them:
| Figure | Calculation | Result |
|---|---|---|
| Per second | 42.2 billion t ÷ 31,536,000 s | 1,338 t |
| Per minute | 1,338 t × 60 | 80,300 t |
| Per day | 42.2 billion t ÷ 365 | 115.6 million t |
| Budget runs out | 170 Gt ÷ 42.2 Gt a year | ≈ 4.0 years |
| China per second | 12.29 billion t (2024) ÷ 31,536,000 s | 390 t |
“So far this year” is simply the per-second rate multiplied by the number of seconds since 1 January. The China, United States and India pages use the same method with each country’s own annual total.
Where the data comes from
- Global totals and the carbon budget: the Global Carbon Budget 2025, the annual assessment by more than 100 scientists of the Global Carbon Project, published in Earth System Science Data. It puts 2025 emissions at 38.1 Gt from fossil fuels and cement (a record, up about 1.1%) plus 4.1 Gt from land-use change.
- Country figures: Our World in Data’s CO₂ dataset, which is based on the Global Carbon Project and covers 213 countries up to 2024.
- Other budget estimates: the Indicators of Global Climate Change project gives a smaller 1.5 °C budget (about 130 Gt). Estimates differ because they use different methods for warming from other gases and for the baseline year.
How accurate is it?
Good enough to show the scale and speed of emissions, but not precise to the tonne:
- Fossil CO₂ is known to within about ±5% globally. National figures for countries with weaker statistics can be less certain.
- Land-use change (mainly deforestation) is far more uncertain; the Global Carbon Budget describes it as one of the largest uncertainties in the whole budget.
- Timing: real emissions are higher in winter in the northern hemisphere and vary by weekday and hour. The counter assumes a steady rate, so it can run slightly ahead or behind at any given moment.
- Lag: country data covers the last complete year (2024). Recent changes, such as a fall in a country’s emissions in 2025, appear only after the next data release.
Putting the numbers in perspective
- A typical petrol car emits about 4.6 tonnes of CO₂ a year (US EPA). The 1,338 tonnes emitted each second equal a year of driving for roughly 290 cars.
- The average person on Earth is responsible for about 4.7 tonnes of fossil CO₂ a year, but this ranges from under 1 tonne in many low-income countries to over 14 tonnes in the United States. Compare countries on the ranking page.
- Land and oceans absorb roughly half of the CO₂ we emit (about 21% and 29% over the past decade); the rest builds up in the atmosphere.
Want to see your own share? Try the carbon footprint calculator.
How often the data is updated
The Global Carbon Budget is published every November or December, and Our World in Data updates its country dataset shortly afterwards. We update the site’s figures after each release; the date at the top of this page shows the latest revision.
Questions and answers
Is the CO₂ counter measured in real time?
No. Nobody measures global CO₂ emissions second by second. The counter spreads the latest annual total from the Global Carbon Budget evenly over the year, so it shows a live estimate of how emissions add up.
How accurate is the CO₂ counter?
The annual fossil CO₂ total behind it is known to within about ±5%. Land-use emissions are much less certain. The counter also assumes a steady rate, while real emissions vary by season, day and hour, so treat the live numbers as good estimates rather than measurements.
How much CO₂ is emitted every second?
About 1,338 tonnes. That is the Global Carbon Budget 2025 estimate of 42.2 billion tonnes a year (fossil fuels plus land-use change) divided by the 31.5 million seconds in a year.
Why do the country numbers not add up to the global total?
Country figures cover fossil-fuel and industry CO₂ only, for the latest complete year (2024). The global counter also includes land-use change and international aviation and shipping, which are not assigned to individual countries.
Sources
- Global Carbon Budget 2025, Friedlingstein et al., Earth System Science Data, 2026
- Global Carbon Project: Global Carbon Budget
- CO₂ emissions, Our World in Data
- Analysis: fossil-fuel CO₂ emissions to set new record in 2025, Carbon Brief, 2025
- Greenhouse gas emissions from a typical passenger vehicle, US EPA