Methodology version v4.0 · Updated 19 May 2026 · Calculator →
This page covers US, EU, UK, and Singapore locales. Version history at the bottom. Errors and corrections: [email protected]
The Decarb calculator estimates a consumption-based personal carbon footprint. It covers Scope 1 emissions (direct combustion — gas, oil, biomass), Scope 2 emissions (purchased electricity and district heating), and selected Scope 3 emissions (flights, purchased goods, food supply chain, and financed impact through banking and investments). Vehicle manufacturing, embodied carbon in housing, and supply chain emissions beyond the food and goods categories are excluded, consistent with standard personal footprint methodology.
All figures are estimates. Category averages are used where individual data is unavailable. The calculator does not claim to produce a verified or audited footprint — it produces an evidence-based estimate suitable for identifying the highest-impact areas for personal reduction. Emission factors are sourced from publicly available, peer-reviewed, or government-published data as detailed below.
Greenhouse gases are expressed as CO₂-equivalent (CO₂e) using Global Warming Potentials from the IPCC Fifth Assessment Report (AR5), 100-year timeframe, consistent with the GHG Protocol and EPA reporting standards. All figures are in tons CO₂e per year.
| Category | Scope | What is included | What is excluded |
|---|---|---|---|
| Transport | Scope 1 / 2 | Tailpipe or grid emissions from personal vehicle use | Vehicle manufacturing; public transit beyond default ‘no car’ factor |
| Home energy | Scope 1 / 2 | Electricity, gas, fuel oil, biomass, district heating | Embodied carbon of home construction; appliance manufacture |
| Flights | Scope 3 | CO₂ per roundtrip by haul type (ICAO ICEC). Radiative forcing multiplier shown separately. | Non-CO₂ effects included only as optional RFI display |
| Lifestyle | Scope 3 | Food (farm to retail), goods and services (EEIO-based spend), waste (landfill CH₄ + WtE) | Food waste beyond behaviour archetype; packaging; recycling credits |
| Finance | Scope 3, Cat. 15 | Estimated financed impact of bank deposits and investments via proportional PCAF allocation | Facilitated (off-balance-sheet) emissions; pension funds beyond investment default |
Transport emissions are calculated as vehicle type emission factor × annual distance, scaled linearly from a baseline distance. Scope 1 (tailpipe) for internal combustion engine vehicles; Scope 2 (grid) for electric vehicles. Vehicle manufacturing is excluded for consistency across all vehicle types.
| Vehicle type | US | EU | UK | Singapore |
|---|---|---|---|---|
| No personal vehicle | 0.45 t CO₂e/yr | 0.45 t CO₂e/yr | 0.38 t CO₂e/yr | 0.38 t CO₂e/yr |
| Hybrid / efficient | 2.4 t @ 12,000 mi (45 MPG) | 1.44 t @ 12,500 km (115 g/km) | 1.82 t @ 11,900 km (153 g/km) | 2.90 t @ 15,000 km (193 g/km) |
| Standard petrol | 4.3 t @ 12,000 mi (25 MPG) | 2.09 t @ 12,500 km (170 g/km) | 2.29 t @ 11,900 km (192 g/km) | 2.90 t @ 15,000 km (193 g/km) |
| Large SUV / truck | 6.3 t @ 12,000 mi (17 MPG) | 3.19 t @ 12,500 km (220 g/km) | 3.32 t @ 11,900 km (279 g/km) | 3.80 t @ 15,000 km (253 g/km) |
| Electric vehicle | 0.34 kWh/mi × grid factor | 0.18 kWh/km × country grid | 0.195 kWh/km × 0.233 kg/kWh | 0.175 kWh/km × 0.408 kg/kWh |
Sources: EPA GHG Hub 2025, full CO₂e (US); EEA new car CO₂ data 2022 (EU); DESNZ GHG Conversion Factors 2024 (UK); LTA Annual Report 2023 / MOT Singapore (SG). Distances scaled linearly from locale baselines. No-vehicle factor includes estimated modal average for public transit: DfT NTS 2023 (UK/SG); EPA modal average (US/EU).
Home energy emissions are calculated in two parts: electricity (grid kWh × grid emission factor) and heating fuel (fuel consumption × fuel emission factor). A 2D lookup table maps housing type × heating type to an annual electricity baseline in kWh. Heating fuel is calculated separately for gas, oil, district heating, and biomass. Electric resistance and heat pump heating are captured entirely through the electricity baseline at their respective COP values — no separate fuel calculation is applied.
| Locale | Factor (kg CO₂e/kWh) | Source | Notes |
|---|---|---|---|
| US national avg | 0.350 | EPA eGRID2023 (Jan + Jun 2025) | Full CO₂e, AR5 GWP. ZIP code lookup for 24 subregions. |
| EU (country-level) | 28–662 g CO₂/kWh | EEA annual GHG intensity 2023 | Norway 28 (hydro) to Poland 662 (coal). 27 EU countries + Norway. |
| UK national | 0.233 | DESNZ GHG Conversion Factors 2024 | Full CO₂e, AR5 GWP. Single national factor. |
| Singapore | 0.408 | EMA Singapore Energy Statistics 2023 | Natural gas dominant (~95%). Updated annually. |
| Fuel | Emission factor | Locales | Source |
|---|---|---|---|
| Natural gas (US) | 5.3 kg CO₂e/therm → ~1.5 t CO₂e/yr typical | US | EPA GHG Hub 2025 |
| Natural gas (EU) | 0.244 kg CO₂e/kWh × 14,000 kWh/yr typical | EU | IPCC / Eurostat |
| Natural gas (UK) | 0.182 kg CO₂e/kWh | UK | DESNZ Conversion Factors 2024, Table 1 |
| Fuel oil (US) | 10.21 kg CO₂e/gallon × housing-type consumption | US | EPA GHG Hub 2025; EIA RECS 2020 |
| Fuel oil / kerosene (UK) | 0.254 kg CO₂e/kWh | UK | DESNZ Conversion Factors 2024, Table 1 |
| District heating (EU) | Country-level, 10–300 g CO₂/kWh heat delivered | EU | National GHG inventories / IEA World Energy Balances 2023 |
| District heating (UK) | 0.136 kg CO₂e/kWh heat delivered | UK | BEIS Heat Networks Data Unit (HNDU) 2023 |
| Wood logs (closed stove) | 0.026 kg CO₂e/kWh (CH₄+N₂O only) | EU, UK | IPCC 2019 GL Vol 2 Ch.2, residential combustion |
| Biomass pellets (EN Plus) | 0.017 kg CO₂e/kWh (CH₄+N₂O only) | EU, UK | IPCC 2019 GL Vol 2 Ch.2 |
Biomass and biogenic carbon
Biogenic CO₂ from sustainably sourced biomass is excluded from the personal footprint under IPCC national inventory accounting and the GHG Protocol Product Standard (IPCC 2019 GL Vol 2, Ch.2). Only non-CO₂ greenhouse gases — methane (CH₄) and nitrous oxide (N₂O) — are included in the factors above, using AR5 GWP values. This treatment assumes certified sustainable sourcing (e.g., EN Plus for pellets). Uncertified wood may carry land-use change emissions not captured in this estimate.
For EU, UK, and Singapore users who have solar water heating, the calculator applies an estimated annual avoided emissions figure. The calculation uses a domestic hot water (DHW) load by housing type and a solar fraction by climate zone, applied against the local heating fuel emission factor. Solar fractions: southern EU / Singapore 55%, UK / northern EU 42% (JRC TABULA 2023; BCA Singapore). DHW loads: flat / apartment 850 kWh/yr, house 1,350 kWh/yr, Singapore 500 kWh/yr (lower due to smaller temperature differential).
Flight emissions are calculated per roundtrip using fixed factors by haul type, derived from the ICAO Carbon Emissions Calculator (ICEC). Values cover CO₂ only from jet fuel combustion. Radiative forcing index (RFI) is shown alongside as an additional context figure but not added to the total, in order to maintain comparability with EPA and ICAO reference tools. According to Lee et al. (2021), the full climate impact of aviation including non-CO₂ effects (contrails, water vapour, nitrogen oxides) is estimated at 1.9–2.7× the CO₂-only figure. Users can view both figures in the calculator.
| Haul type | CO₂ per roundtrip (t CO₂e) | Duration proxy | Source |
|---|---|---|---|
| Short-haul | 0.296 | Up to ~3 hours | ICAO ICEC |
| Medium-haul | 0.608 | 3–7 hours | ICAO ICEC |
| Long-haul | 0.775 | Over 7 hours | ICAO ICEC |
Food emissions are estimated using diet archetype factors covering farm-to-retail emissions. Values are consistent across all locales as the underlying food supply chains are globally comparable at the archetype level.
| Diet | t CO₂e/yr | Source |
|---|---|---|
| Vegan | 0.4 | Poore & Nemecek 2018 |
| Vegetarian | 1.2 | Heller & Keoleian 2015 |
| Flexitarian | 1.7 | USDA / Poore & Nemecek 2018 |
| Omnivore | 2.3 | USDA / CoolClimate |
Goods emissions are estimated using monthly spending brackets applied against a carbon intensity factor derived from Exiobase 3.8.2 environmentally extended input-output (EEIO) data. The base year is 2019; an inflation correction is applied for each locale to express values at 2025 prices. Figures represent the supply chain emissions of purchased goods and services excluding categories captured elsewhere (housing energy, food, transport).
| Spend bracket | US (t CO₂e/yr) | EU (t CO₂e/yr) | UK (t CO₂e/yr) | SG (t CO₂e/yr) |
|---|---|---|---|---|
| Low | 0.50 (<$150/mo) | 0.27 (<€150/mo) | 0.30 (<£150/mo) | 0.28 (<SGD 200/mo) |
| Medium-low | 1.10 ($150–300) | 0.81 (€150–300) | 0.88 (£150–300) | 0.85 (SGD 200–500) |
| Medium-high | 1.95 ($300–500) | 1.44 (€300–500) | 1.58 (£300–500) | 1.55 (SGD 500–800) |
| High | 2.75 (>$500/mo) | 2.16 (>€500/mo) | 2.38 (>£500/mo) | 2.30 (>SGD 800/mo) |
Sources: Exiobase 3.8.2 (all locales). US CPI inflation correction +25% (2019–2025, BLS); EU HICP +22% (Eurostat); UK CPI +27% (ONS); SG CPI proxy via SGD/USD 0.74. EU values are 54–79% of US equivalents, reflecting lower EU manufacturing carbon intensity and stronger eco-design regulation. UK values are derived from Exiobase 3.8.2 UK household supply-use table.
| Behaviour | US | EU | UK | Singapore |
|---|---|---|---|---|
| No recycling | 0.42 t | 0.14 t | 0.19 t | 0.14 t |
| Recycling | 0.27 t | 0.07 t | 0.10 t | 0.08 t |
| Minimalist | 0.15 t | 0.03 t | 0.04 t | 0.03 t |
Sources: EPA WARM v15 (US); Eurostat env_wasmun 2023 + IPCC 2019 GL Vol 5 (EU); DEFRA UK Stats on Waste 2023 + IPCC 2019 GL Vol 5 (UK); NEA SG Waste Statistics 2023 + IPCC 2019 GL Vol 5 (SG). EU values are 50–80% below US due to mandatory landfill gas capture (EU Landfill Directive), higher waste-to-energy penetration (~25% vs ~13%), and lower per-capita MSW generation.
The finance section estimates the climate impact of bank deposits and investments through a proportional allocation method: bank total financed emissions ÷ total assets × user balance. This approach is used by platforms such as MotherTree and GreenFi, and is grounded in the Partnership for Carbon Accounting Financials (PCAF) v3 standard for financial institutions’ Scope 3 Category 15 disclosures.
| Category | US | EU | UK | Singapore |
|---|---|---|---|---|
| Standard bank | 0.240 kg CO₂e/$-yr | 0.155 kg CO₂e/€-yr ① | 0.185 kg CO₂e/£-yr ② | 0.200 kg CO₂e/SGD-yr ③ |
| Green / fossil-free bank | 0.057 kg CO₂e/$-yr | 0.045 kg CO₂e/€-yr | 0.043 kg CO₂e/£-yr | 0.055 kg CO₂e/SGD-yr |
| Standard investment fund | 0.033 kg CO₂e/$-yr | 0.033 kg CO₂e/€-yr | 0.033 kg CO₂e/£-yr | 0.030 kg CO₂e/SGD-yr |
| Green / ESG fund | 0.017 kg CO₂e/$-yr | 0.015 kg CO₂e/€-yr | 0.017 kg CO₂e/£-yr | 0.015 kg CO₂e/SGD-yr |
| Default bank balance | $8,000 | €5,000 | £7,000 | SGD 12,000 |
| Default investment balance | $87,000 | €20,000 | £35,000 | SGD 85,000 |
① EU standard bank factor revised from 0.24 to 0.155 kg CO₂e/€-yr, reflecting Carbone 4 national average for French banks (481 t CO₂e/€M) adjusted for ECB data showing a 43% reduction in EU bank loan portfolio carbon intensity from 2018 to 2023 (ECB, November 2025). This remains a single-value proxy across EU27; country-level calibration is deferred pending CSRD ESRS E1 disclosures (2025–2026 cycle).
② UK standard bank factor based on MotherTree PCAF-aligned bank league table 2023 (Barclays, Lloyds, Nationwide blended average). Green bank factor reflects Triodos Bank / Co-operative Bank average.
③ Singapore factor is an Asia-Pacific proxy from the PCAF 2023 database, adjusted for MAS Green Finance Action Plan 2.0 estimated uptake (~15% of portfolio). MAS mandates financed emissions disclosure from 2024; SG-specific institutional data is expected to become available in 2025–2026. This figure should be treated as an estimate.
Balance defaults: US — Fed SCF 2022; EU — ECB HFCS 2021; UK — ONS Wealth and Assets Survey 2020–22 / BoE FCA Financial Lives 2022; SG — MAS Financial Stability Review 2023 / CPF Board Annual Report 2023 (SGD 85,000 includes CPF Ordinary Account median for working-age adults). All sliders are user-adjustable.
| Country / region | Per-capita average (consumption) | Source |
|---|---|---|
| United States | ~15.2 t CO₂e/yr | EPA GHG Inventory 2023 |
| European Union avg | ~8.0 t CO₂e/yr | EEA / Eurostat 2023 |
| United Kingdom | ~5.5 t CO₂e/yr | ONS Environmental Accounts 2023 (consumption-based) |
| Singapore | ~7.5 t CO₂e/yr | NEA Singapore GHG Inventory 2022 (consumption-based estimate) |
| 1.5°C target (2030) | ~2.5 t CO₂e/yr | IPCC SR1.5 / C40 Cities |
The following limitations are documented openly. They do not prevent the calculator from producing a useful estimate, but users should be aware of them.
EU banking factor is a single-value proxy. The EU banking emission factor (0.155 kg CO₂e/€-yr) is derived from French bank data (Carbone 4) adjusted for ECB portfolio trends. It does not vary by EU country. Country-level calibration is deferred pending CSRD ESRS E1 disclosures (target: v2.5).
Singapore finance factor is an Asia-Pacific proxy. No SG-specific PCAF institutional data is currently available. MAS financed emissions disclosures are expected from 2025–2026 under the MAS Green Finance Action Plan 2.0. The factor will be updated when data is available.
District heating — within-country variation. Country-level EU district heating factors overstate emissions for users on clean networks and understate for users on coal-heavy networks. The within-country range can be 10× in countries with mixed networks. Network-specific factors require integration with national utility registries, which is deferred to a future version.
UK goods brackets are Exiobase proxy estimates. UK goods values use Exiobase 3.8.2 UK household supply-use table with ONS CPI inflation correction. These are estimates pending direct validation against ONS Household Final Consumption Expenditure carbon intensity data.
Facilitated (off-balance-sheet) bank emissions are excluded. PCAF Part B covers emissions from capital market facilitation activities (bond underwriting, syndicated loan arranging). These are not included in the standard bank emission factors, which means the figures may understate the climate impact of deposits at large global banks with significant underwriting operations.
The calculator produces an evidence-based estimate using published emission factors from government and international sources. Accuracy varies by category: transport and energy calculations are relatively precise because they use actual usage inputs; lifestyle categories (food, goods, waste) use category averages rather than individual item data. The estimate is sufficient to identify the highest-impact areas for reduction and to track progress over time, but it is not an audited or verified footprint.
The UK locale uses DESNZ (Department for Energy Security and Net Zero) GHG Conversion Factors 2024 for grid electricity (0.233 kg CO₂e/kWh), natural gas (0.182 kg CO₂e/kWh), and fuel oil. Electricity consumption baselines are derived from OFGEM/BEIS Energy Consumption in the UK (ECUK) 2023 and the BRE NEED dataset 2023, by housing type and heating system. Transport factors use DESNZ 2024 vehicle emission rates, and the annual mileage default is 11,900 km from the DfT National Travel Survey 2023.
Singapore uses the EMA (Energy Market Authority) grid emission factor of 0.408 kg CO₂e/kWh from the Singapore Energy Statistics 2023. The residential electricity model is all-electric — Singapore has no gas grid for residential use — with electricity baselines by HDB flat type and private housing taken from EMA SES 2023 and SP Group data, including air conditioning load. Transport uses LTA annual report 2023 vehicle emission factors and a default distance of 15,000 km/year. The national benchmark of ~7.5 t CO₂e/yr is from the NEA Singapore GHG Inventory 2022.
Biogenic CO₂ from sustainably sourced biomass is excluded under the IPCC national inventory accounting framework (IPCC 2019 GL Vol 2, Chapter 2). The IPCC treats this carbon as part of the land-use sector rather than the energy sector, on the basis that sustainably managed biomass re-absorbs the CO₂ over the growth cycle. The Decarb calculator follows this standard treatment but includes the non-CO₂ greenhouse gases from biomass combustion — methane (CH₄) and nitrous oxide (N₂O) — which are not biogenic. This treatment assumes certified sustainable sourcing, such as EN Plus certification for pellets. Deforestation risk from uncertified wood is not captured.
The finance section shows the estimated emissions associated with your bank deposits and investment portfolio through your financial institution’s lending and investment activities. The calculation applies a proportional allocation: the bank’s total financed emissions (per the PCAF standard) ÷ total assets × your balance. This is the same approach used by MotherTree and GreenFi. The figure is labelled “estimated financed impact” rather than a personal Scope 3 emission because under the GHG Protocol, financed emissions formally belong to the financial institution’s Scope 3 inventory. The figure is an order-of-magnitude indicator to illustrate the climate consequence of choosing a high-carbon versus low-carbon financial institution.
Decarb reviews and updates emission factors annually, or when a material new data publication is released. The US grid factor uses EPA eGRID, updated annually in Q1. EU grid factors use EEA annual GHG intensity data, typically updated in spring. UK factors use DESNZ Conversion Factors, published annually in June. The Singapore EMA factor is updated annually. Finance factors are reviewed against PCAF database updates, which follow CSRD disclosure cycles. Version history is documented below.
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| Version | Date | Changes |
|---|---|---|
| v4.0 | May 2026 | Added UK and Singapore locales. Added biomass/wood heating (IPCC 2019 GL Vol 2, CH₄+N₂O only). Added solar water heating. Revised EU banking factor 0.24 → 0.155 (Carbone 4 / ECB 2025). Added UK banking factor 0.185 (MotherTree). Added SG banking factor 0.200 (PCAF AP proxy). New balance defaults for UK and SG. Finance relabelled “estimated financed impact”. |
| v2.3 | March 2026 | US + EU. eGRID2023 grid factors. EU housing kWh baselines (ODYSSEE-MURE 2023). EU goods brackets (Exiobase 3.8.2, HICP-corrected). EU waste factors (Eurostat 2023). All transport recalculated to full CO₂e. Fuel oil by housing type. EU district heating country factors. |
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