Carbon footprint questions —
answered clearly.

Decarb is a personal carbon measurement platform. We help you calculate your estimated carbon footprint across eight lifestyle categories — flights, home energy, food, waste, goods and services, finance, hobbies, and ground transport — and show you exactly where reduction has the most impact.

The result is a structured report: your estimated emissions in tons CO₂e per year, broken down by category, benchmarked against national and global averages, and paired with a prioritised action plan.

You answer 15 questions about your lifestyle — your housing type, energy source, diet, transport habits, and spending patterns. We apply verified emission factors from sources including the US EPA, ICAO, IPCC, and Exiobase to calculate your estimated total footprint in tons CO₂e per year.

The calculation takes around 3 minutes. No account is required. Your report is generated immediately.

Yes. The carbon footprint calculator and report are free. No account is required. The only paid element of Decarb is carbon offset purchasing, which is optional.

Your Decarb report includes a prioritised action plan — the specific changes that would reduce your footprint the most, ranked by estimated impact. These are based on your individual profile, not generic advice.

The most effective actions vary by person. For most people in the US, ground transport, home energy, and diet are the highest-impact categories. The report tells you which applies to you.

A carbon footprint is the total greenhouse gas emissions caused directly and indirectly by a person, household, or organisation over a given period. It covers emissions from activities like driving, flying, heating your home, and the goods and services you consume. Decarb calculates your personal carbon footprint and expresses it in tons CO₂e per year.

CO₂e stands for carbon dioxide equivalent. It is the standard unit used to compare emissions across different greenhouse gases by converting them to the equivalent warming effect of CO₂ over a 100-year period (GWP100). We always express results in tons CO₂e — the internationally accepted standard for personal carbon accounting.

Climate change refers to long-term shifts in global temperatures and weather patterns. Since the Industrial Revolution, human activity — primarily the burning of fossil fuels — has caused greenhouse gas concentrations to rise sharply. Atmospheric CO₂ has not exceeded 300 parts per million in at least 650,000 years. Current levels are above 420 ppm and rising.

Greenhouse gases are gases that absorb and re-emit infrared radiation, trapping heat in the atmosphere. The main ones are CO₂, methane (CH₄), and nitrous oxide (N₂O). Methane is approximately 28 times more potent than CO₂ over a 100-year period — which is why all emissions are expressed in CO₂e for fair comparison.

A carbon sink is a system that absorbs more CO₂ from the atmosphere than it releases. Forests, soils, and oceans are the largest natural carbon sinks. Some offset projects involve protecting or restoring natural sinks — for example, preventing deforestation or restoring degraded land.

The calculator produces estimates. All personal carbon calculators produce estimates — the inputs are self-reported and the emission factors are averages. Accuracy varies by category. Transport and energy carry relatively high confidence. Food and goods carry more uncertainty.

The goal is not false precision — it is to correctly identify which categories are driving your footprint and what the highest-impact actions are. Full methodology is documented on our methodology page.

We use emission factors from: US EPA Emissions Factors Hub (transport and energy), ICAO Carbon Emissions Calculator (flights), GHG Protocol (accounting standards), Poore & Nemecek (2018) and USDA (food), Exiobase (goods and services), PCAF (financed emissions), and US EIA and eGRID (home energy). All factors are documented on our methodology page.

Finance emissions reflect how your savings and investments are used by banks and funds to finance economic activity — including fossil fuel projects. These are known as financed emissions (Scope 3, Category 15 under the GHG Protocol).

Our finance calculation assumes typical US balances: $20,000 in a bank account and $100,000 invested. For a standard portfolio, this produces approximately 6 tons CO₂e per year — often the single largest category. Switching to fossil-free banking and green investment funds can reduce this to approximately 2 tons CO₂e. Full assumptions are on our methodology page.

Decarb covers the eight lifestyle categories that account for the majority of a typical personal footprint. Some categories are outside scope — including government allocation, infrastructure embodied carbon, and some supply chain emissions. This means the estimate is likely conservative — your actual footprint may be somewhat higher.

A carbon offset represents a reduction or removal of one ton of CO₂e from the atmosphere, achieved by a verified project elsewhere — for example, protecting a forest from deforestation, capturing methane from a landfill, or funding renewable energy. When you purchase an offset, the credit is retired on your behalf and cannot be resold or recirculated.

No. Decarb does not make carbon neutral claims. Purchasing offsets retires a specific quantity of CO₂e credits against your footprint — it does not eliminate the underlying emissions. Offsetting is most useful as a complement to reduction, not a substitute for it.

All offset projects are certified under UNFCCC Certified Emission Reductions (CERs) or Verra VCS. Third-party audit documentation is required for all projects. We do not accept self-certified or unregistered credits.

After purchase, Decarb retires the credits on your behalf in the relevant registry within 7 days. You receive email confirmation once retirement is complete. Retired credits cannot be resold or reused.

No. Carbon credits are non-refundable once retired. Full terms are available on our terms of use page.

It may be, depending on the laws of your country of residence. Decarb cannot provide tax advice. Please consult a qualified local professional.