A carbon calculator for people who like numbers

4.2 tonnes of CO₂. That's your year — if you're average.

CO2Mate logs your daily activities and shows your real footprint — measured against country averages, not aspirational green-washing. The numbers come from DEFRA, the EPA, and Our World in Data. The interpretation is up to you.

Find your number — free See the breakdown ↓ No offsets sold. We mean it.

Per-capita CO₂ — annual

tonnes / year · 2023

Where the average person stands. Vertical reference is the Paris-aligned ceiling — what every adult would need to emit to keep warming under 1.5°C.

Your country (UK)

8.3t

EU average

6.8t

Global average

4.7t

Paris-aligned

2.3t

You

—

Sources: Our World in Data · DEFRA · Eurostat · IPCC AR6 WGIII

↓ Methodology

§ 02 · The composition

This is what the average looks like.

Roughly where the typical European's 4.7 tonnes comes from. The numbers behind transport are the most volatile — one transatlantic flight can re-shape your entire year.

Transport

cars, flights, rail

30%

1.41t

Energy

heating, electricity

25%

1.18t

Food

meat, dairy, produce

20%

0.94t

Goods

clothes, electronics

15%

0.70t

Services

banking, healthcare

10%

0.47t

This is what the average looks like. You'll find out where yours differs — and the size of those differences is usually larger than people expect.

§ 03 · Four data-led ideas

What the app actually does.

No streaks. No badges. No "you saved 0.4 plastic straws this week." Just measurement, comparison, and the math behind decisions you might be considering.

Daily logging — tap your commute, your meal, your purchase.

Activities map to emissions factors in the background. Nothing manual to convert. Average entry takes 12 seconds.

Benchmarked against your country — not against influencers.

We compare you to the actual per-capita averages of the country you live in. The Paris-aligned line is also visible. Everyone else's lifestyle blog is not.

Scenario modeling — what if you flew less? What if you went vegetarian?

See the math, before the commitment. Each scenario uses real DEFRA / EPA factors — we don't round up or round down to flatter you.

Year-over-year trends — what's actually moved?

Most footprint apps log a single number, once. Ours keeps the line going, year after year, so you can see whether anything has actually changed.

§ 04 · Try it now

What if you changed something?

A live model of an annual UK footprint. Move the controls and watch the math. The same engine runs in the app — it just doesn't know your starting point yet.

Scenario modeling

live · kg CO₂e factors from DEFRA 2024

Move the sliders. The number to the right is your modelled annual footprint against the UK average. We show you the math, not the marketing.

Long-haul flights per year 2 × 1.6t ≈ 3.2t

Driving distance per year 12,000 km · 2.16t

Diet baseline

Drive EV Heat pump

YOUR MODELLED FOOTPRINT

8.3t CO₂ / yr

+0.0t vs UK average (8.3t)

Flights

3.20t

Driving

2.16t

Food

2.30t

Home

2.10t

Goods

0.90t

Round-trip LHR→JFK ≈ 1.6t · Small ICE car · 0.18 kg/km · DEFRA 2024 GHG factors

Open methodology

What doesn't help

"CO2Mate doesn't sell offsets. We don't think planting trees in Madagascar absolves a transatlantic flight. We show you the number."

— from the methodology, 2026

§ 05 · Where our numbers come from

Climate-data integrity is the trust signal.

We publish every factor we use. We update them quarterly. When a number is uncertain we say so. We do not replace measurement with optimism.

Source	Dataset	Updated
DEFRA UK Transport, energy	GHG conv factors v2024	Q1 2026
EPA US US activities	GHG Emission Factors Hub	Q1 2026
Our World in Data Country averages	per-capita CO₂ 1850–2023	Q4 2025
IPCC AR6 WGIII Paris-aligned target	Ch.5 — Lifestyles	2022
Eurostat EU comparisons	env_ac_aigg_q	Q1 2026
Poore & Nemecek Food factors	Science 2018 · 360, 987	—

All factors expressed in kg CO₂-equivalent (kgCO₂e). Where flight uplift uses radiative forcing, multiplier = 1.9× (DEFRA 2024).

Per-capita CO₂ — selected countries

t / person / yr · 2023

Hover a circle.

Below global avg (< 4.7t) Near global avg Above global avg Circle size ∝ tonnes / person / yr · 2023 · OWID

§ 06 · Honestly answered

Questions people ask.

How accurate is this?

Personal carbon accounting carries roughly ±20% uncertainty, which is good enough to spot which decisions matter and which don't. The single biggest source of error is usually the user — we lean on activity tagging rather than gut estimates. Factor sources are listed in the methodology section above. ±20%

Why don't you offer offsets?

Most voluntary carbon offsets do not deliver the reductions claimed (see Guardian / Die Zeit / SourceMaterial joint investigation, 2023; Probst et al., Nature, 2024). Selling offsets alongside a measurement tool would dilute the measurement. We'd rather be useful than upsell.

What if my country isn't supported?

We currently cover the EU-27, UK, US, Canada, Australia, NZ, Japan, and Korea with country-specific factors. For everywhere else we use OWID per-capita averages and flag the comparison as such. Add your country to the wait-list inside the app.

Does the app use AI?

No. The app does activity → emissions-factor lookups against published datasets. That math doesn't require AI, and we'd rather be transparent than impressive.

What does the $1.99/month unlock?

Year-over-year trends, country comparisons, and scenario modeling beyond a single what-if. The free tier — daily logging, monthly footprint, methodology — is real and stays real. We are not stripping things out of it.

Where is my data stored?

Encrypted on-device by default. If you opt into cloud sync, data is stored in the EU (Frankfurt) under GDPR. We don't sell behavioural data and we'd find a buyer disappointing even if we did.

§ 07 · Begin

Find your number.

Coming soon to iOS and Android. Free, with $1.99/month for year-over-year trends and country comparisons — or stay free, the basics will be real.

Coming to the App Store Soon Coming to Google Play Soon

Targeting public launch later this year · No third-party trackers · GDPR-compliant