The Science

Every score backed by peer-reviewed research.

EcoScore calculates your daily carbon footprint using verified emission factors from the world's most authoritative scientific and governmental sources. No estimates. No vague math. Every factor is traceable to a published study or official dataset.

How It Works

How we calculate your EcoScore

Your daily EcoScore is computed from the activities you log — commuting, food, home energy, and lifestyle choices. Each activity is multiplied by its corresponding emission factor: a published figure representing the kg of CO₂ equivalent (CO₂e) released per unit of that activity.

All emission factors in EcoScore are expressed as kg CO₂ equivalent (CO₂e) using IPCC AR5 Global Warming Potential (GWP100) values. This is the same standard used in national greenhouse gas inventories submitted to the UNFCCC — and the same framework used in World Bank Climate Finance operations.

We update our factor library annually, in line with the EPA eGRID and GHG Emission Factors Hub release cycles. The science team is led by co-founder Aprajita, a climate specialist with deep expertise in carbon accounting and climate policy across emerging economies.

Data Sources By Category

What powers each part of your score

🚗

Transport

Factors used for: car commutes, EV driving, public transit, cycling, flights

Primary source: US EPA GHG Emission Factors Hub (2025) · EPA-420-F-23-014 (2023)

Key detail: EV emission factors are grid-adjusted using EPA eGRID 2025 at the regional level — because an EV in Washington State (hydro grid) emits up to 5× less than one in a coal-heavy grid.

🍽️

Food

Factors used for: beef, poultry, fish, dairy, plant-based meals, portion sizes

Primary source: Poore & Nemecek (2018), Science Vol. 360 — 38,000 farms, 119 countries

Key detail: This is the most comprehensive food systems lifecycle analysis ever published. It is the source used by the UN FAO, Our World in Data, and the majority of peer-reviewed carbon accounting tools.

🏠

Home Energy

Factors used for: electricity, natural gas, heating oil, appliance use, EV home charging

Primary source: US EPA eGRID 2025 (electricity) · EPA GHG Emission Factors Hub (natural gas, heating)

Key detail: Electricity emission factors vary significantly by US region. International users receive country-level factors from IEA Emission Factors 2023.

🌿

Lifestyle

Factors used for: consumer goods, smoking, dietary patterns, waste

Primary sources: WHO Tobacco lifecycle studies · Scarborough et al. (2023), Nature Food · University of Michigan Carbon Footprint Factsheet (2024)

Key detail: Lifestyle factors are supplementary to the core transport, food, and energy categories and are used to provide a more complete daily picture.

Food & Diet

Food & Diet

Primary source: Poore & Nemecek (2018), Science — the largest meta-analysis of global food systems, covering 38,000 farms across 119 countries.

Food Item kg CO₂e per kg Per Typical Serving Notes
Beef (beef herd)60–100~15.5 kg per 100 gHighest of all foods; methane from ruminant digestion
Lamb & mutton~39~5.8 kg per 100 gSecond highest; also a ruminant
Dark chocolate~19~0.95 kg per 50 g barDeforestation for cocoa a major factor
Cheese~13.4~1.3 kg per 100 gDairy production is emissions-intensive
Pork~7.6~2.4 kg per 100 g
Chicken / poultry~6–7~1.8 kg per 100 g~4× lower than beef
Farmed fish~5~1.3 kg per 100 gVaries widely by species and farming method
Eggs~4.5~0.27 kg per egg
Cow’s milk~2.4 / litre~0.6 kg per 250 ml
Rice~2.5~0.5 kg per 200 g cookedMethane from flooded paddies
Wheat / bread~2.5~0.1 kg per slice
Tofu~2~0.08 kg per 100 gMuch lower than any meat
Vegetables (avg)0.5–2~0.05–0.1 kg per 100 gWide variation by type and season
Beans / legumes~0.9~0.09 kg per 100 g
Nuts~0.5~0.05 kg per 100 g
Tomatoes~0.5~0.32 kg per 150 gHigher if grown in heated greenhouses
Apples~0.4~0.06 kg per apple
Bananas~0.7~0.11 kg per banana
Potatoes~0.5~0.05 kg per 100 g

Key Food Comparisons

  • Beef emits roughly 10–20× more CO₂e per kg than chicken
  • Beef emits 60–200× more CO₂e per kg than most vegetables
  • A meat-heavy diet produces ~3.3 t CO₂e/year; a vegan diet produces ~1.5 t CO₂e/year
  • Switching from beef to chicken for one meal per day saves approximately 1.5 t CO₂e/year
  • Per 100 g of protein, beef emits 20× more than lentils
Transportation

Transportation

Primary sources: US EPA GHG Emission Factors Hub (2025); EPA Automotive Trends Report (2024); European Environment Agency; ICCT.

Mode CO₂e Factor Annual Impact (typical) Notes
Long-haul flight~0.41 lbs (186 g) CO₂e/pass-mile~800 kg per return flightDoes not include radiative forcing multiplier
Short-haul flight~0.41 lbs CO₂e/pass-mile~400 kg per return flightPer European Environment Agency
SUV / light truck~490 g CO₂/mile~5.5 t CO₂/yearBased on avg 11,500 miles/yr
Gas car (average)404 g CO₂/mile~4.6 t CO₂/yearEPA avg: 22.2 mpg, 11,500 mi/yr
EV (US grid average)~100–200 g CO₂e/mile~1.1–2.3 t CO₂/yearVaries 5× by regional grid; no tailpipe
EV (clean grid)~30–60 g CO₂e/mile~0.3–0.7 t CO₂/yearHydro/renewable-heavy states (WA, CA)
EV (coal-heavy grid)~250–300 g CO₂e/mile~2.8–3.5 t CO₂/yearSimilar to efficient gas cars
Motorcycle~100–150 g CO₂/mile~1.1–1.7 t CO₂/year
Bus (avg occupancy)~89 g CO₂/pass-mile~0.5 t CO₂/year (daily)Per EPA Scope 3 factors
Train / metro~14 g CO₂/pass-mile~0.08 t CO₂/yearEuropean Environment Agency
E-bike~8–15 g CO₂e/mile~0.05 t CO₂/yearIncluding electricity for charging
Bicycle~5 g CO₂e/mile~0 in useMostly from manufacturing
Walking0 g CO₂/mile0

EV Regional Electricity Factors (US, EPA eGRID 2025)

EV emissions depend entirely on the local electricity grid. This is critical for EcoScore’s energy intelligence feature.

Region / State Grid CO₂ Factor EV Effective Emission
Pacific Northwest (WA, OR)~100 g CO₂/kWh~25–35 g CO₂/mile
California~200 g CO₂/kWh~50–65 g CO₂/mile
National average (US)~386 g CO₂/kWh~100–120 g CO₂/mile
Midwest (coal states)~600–700 g CO₂/kWh~200–280 g CO₂/mile
Home Energy

Home Energy

Primary sources: US EPA eGRID (2025); EPA GHG Emission Factors Hub (2025); IEA Emission Factors (2023); Energy Information Administration (EIA).

Activity CO₂e Factor Typical Annual Impact Notes
US avg grid electricity386 g CO₂/kWh~1.4 t per avg household2025 national average; varies by state
Natural gas heating5.3 kg CO₂/therm~2 t per avg homePer EPA stationary combustion factors
Propane5.7 kg CO₂/gallon~1.5 t per avg home
Heating oil10.2 kg CO₂/gallon~2.5 t per avg homeHighest of heating fuels
Average US household—~7.5 t CO₂e/yearElectricity + heating combined
Solar electricity (lifecycle)~20–50 g CO₂e/kWh95% less than coalIncludes panel manufacturing
Wind electricity (lifecycle)~7–15 g CO₂e/kWh98% less than coal
Dishwasher (per cycle)~0.7 kg CO₂e~255 kg/year (daily use)Run during off-peak for lower grid emissions
Washing machine (warm)~0.6 kg CO₂e / cycle~120 kg/yearCold wash saves ~0.4 kg/cycle
Hot shower (8 min, gas)~0.5 kg CO₂e~182 kg/year
Streaming (4K TV, 1 hr)~36 g CO₂e~13 kg/year if dailyDevice + network + data center
EV home charging (US avg)~386 g CO₂/kWhVaries by drivingOff-peak charging recommended

International Grid Factors (IEA 2023)

Country Grid CO₂ Factor
France~57 g CO₂/kWh (nuclear-heavy)
Germany~385 g CO₂/kWh
United Kingdom~233 g CO₂/kWh
India~708 g CO₂/kWh
China~581 g CO₂/kWh
Australia~610 g CO₂/kWh
Brazil~106 g CO₂/kWh (hydro-heavy)
Lifestyle

Lifestyle & Consumer Goods

Primary sources: WHO tobacco lifecycle studies; published LCA (lifecycle assessment) literature; EPA consumer goods data.

Activity / Item CO₂e Estimate Notes
Smoking — 1 cigarette~14 g CO₂eProduction + combustion; ~5.1 kg/year for 1/day habit
Smoking — 1 pack (20)~280 g CO₂eTobacco farming is land and energy intensive
Cup of coffee (with milk)~200–340 g CO₂eBlack coffee: ~60 g; espresso: ~60–100 g
Cup of coffee (black)~60 g CO₂eMostly from coffee bean farming
Plastic bag (single use)~1.6 kg CO₂eReusable bag offsets after ~10 uses
Cotton t-shirt (new)~7 kg CO₂eFull lifecycle; US avg 53 items/year = ~370 kg CO₂e/yr
Jeans (new)~33 kg CO₂eCotton farming + dyeing + manufacturing
New smartphone~70 kg CO₂e~80% from manufacturing, not use
New laptop~300–400 kg CO₂eManufacturing dominates; keep devices longer
New car (manufacturing)~6–35 t CO₂eVaries hugely by vehicle type and battery size
Tree planted−21 kg CO₂/year absorbedOffset, not a substitute for emissions reduction
Vegan diet (annual)~1.5 t CO₂e/yearShrink That Footprint (2012)
Vegetarian diet (annual)~1.7 t CO₂e/year
Average omnivore diet~2.5 t CO₂e/year
Meat-heavy diet (annual)~3.3 t CO₂e/year
Global Context

Context: Global Benchmarks

These benchmarks give users meaningful context for their personal EcoScore.

Benchmark CO₂e Figure Source
Global average per capita~4.8 t CO₂e/yearEDGAR 2024
US average per capita~14–15 t CO₂e/yearEPA / EDGAR 2024
EU average per capita~6.8 t CO₂e/yearEuropean Environment Agency
India average per capita~2.4 t CO₂e/yearEDGAR 2024
Target for 1.5 °C pathway (by 2030)2.3 t CO₂e/year per personIPCC AR6
Target for 2 °C pathway (by 2030)~3.0 t CO₂e/year per personIPCC AR6
US reduction needed vs current~80–85% reductionIPCC AR6
Top 1% global emitters~74 t CO₂e/capita/yearOxfam / Stockholm Environment Institute
Bottom 50% global emitters~1 t CO₂e/capita/yearOxfam / Stockholm Environment Institute

18 sources. Every number traceable.

Organized into three tiers by source type.

Primary Official Sources

Tier 1
1

US EPA — GHG Emission Factors Hub (2025)

Emission Factors for Greenhouse Gas Inventories. Center for Corporate Climate Leadership, Jan 2025.

epa.gov/climateleadership/ghg-emission-factors-hub

Transport, electricity, commuting, waste, stationary combustion.

2

US EPA — Typical Passenger Vehicle Emissions

EPA-420-F-23-014, June 2023.

epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle

Car and vehicle emission factors.

3

US EPA — eGRID 2025

Emissions & Generation Resource Integrated Database.

epa.gov/egrid

Regional/state-level electricity; EV calculations.

4

US EPA — U.S. GHG Emissions & Sinks: 1990–2023

Report EPA 430-R-25-003.

epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks

Sector-level US emission data and trends.

5

IPCC — Emissions Factor Database (EFDB)

Intergovernmental Panel on Climate Change.

ipcc-nggip.iges.or.jp/EFDB/main.php

Global emission factors; national inventories.

6

IPCC — AR6, WG III (2022)

Mitigation of Climate Change.

ipcc.ch/report/ar6/wg3

1.5 °C and 2 °C per-capita targets.

7

IEA — Emission Factors 2023

International Energy Agency.

iea.org/data-and-statistics/data-product/emissions-factors-2023

Country-level electricity grid factors.

8

EDGAR — Global Atmospheric Research (2024)

European Commission Joint Research Centre.

edgar.jrc.ec.europa.eu/report_2024

Global per-capita emissions; food system data.

Peer-Reviewed Science

Tier 2
9

Poore & Nemecek (2018)

“Reducing food’s environmental impacts.” Science, Vol. 360, pp. 987–992.

doi.org/10.1126/science.aaq0216

38,000 farms, 119 countries. Gold standard for food factors.

10

Ritchie & Roser — Our World in Data

Environmental Impacts of Food. University of Oxford.

ourworldindata.org/environmental-impacts-of-food

Visualizations based on Poore & Nemecek.

11

Ritchie, H. (2020)

“Carbon footprint of foods: methane?” Our World in Data.

ourworldindata.org/carbon-footprint-food-methane

Methane’s role in food emission comparisons.

12

Scarborough et al. (2023)

Nature Food, Vol. 4, pp. 565–574.

doi.org/10.1038/s43016-023-00795-w

Diet-level annual CO₂e comparisons.

Supporting Sources & Tools

Tier 3
13

Climatiq — Emission Factors API

70,000+ factors, 300+ regions, GHG Protocol compliant.

climatiq.io/data

Aggregates EPA, IPCC, IEA, ecoinvent.

14

GHG Protocol — Scope 3 Guidance

World Resources Institute & WBCSD.

ghgprotocol.org/scope-3-technical-calculation-guidance

Corporate reporting methodology alignment.

15

U. Michigan — Carbon Footprint Factsheet (2024)

Center for Sustainable Systems.

css.umich.edu/.../carbon-footprint-factsheet

Consumer statistics & US household benchmarks.

16

EEA — CO₂ Emission Intensity (Transport)

European Environment Agency.

eea.europa.eu/.../co2-emission-intensity-of-passenger

European transport comparisons.

17

WHO — Tobacco and the Environment

World Health Organization.

who.int/news-room/fact-sheets/detail/tobacco

Smoking lifecycle emissions.

18

US DOE — Beyond Tailpipe Calculator

fueleconomy.gov.

fueleconomy.gov/feg/Find.do

ZIP-level EV emission calculations.

Staying Current

Our data update commitment

EPA eGRID
Annual (January)
Update energy emission factors each January
EPA Emission Factors Hub
Annual (January)
Review transport factors each January
IEA Emission Factors
Annual
Update international grid factors annually
Poore & Nemecek (2018)
Monitor
Watch for updated food LCA meta-analyses
EDGAR
Annual
Update global per-capita benchmarks annually
IPCC AR7
Expected ~2028
Prepare to update GWP values when published
UN Sustainable Development Goals

EcoScore and the global climate agenda

EcoScore's mission is directly aligned with the United Nations Sustainable Development Goals. Our work contributes to:

UN Sustainable Development Goal 13: Climate Action

SDG 13 — Climate Action

Enabling measurable individual carbon accountability at scale

UN Sustainable Development Goal 11: Sustainable Cities and Communities

SDG 11 — Sustainable Cities and Communities

Smart commute tracking that rewards low-carbon transport choices

UN Sustainable Development Goal 12: Responsible Consumption and Production

SDG 12 — Responsible Consumption and Production

Food footprint logging that surfaces the real environmental cost of dietary choices

UN Sustainable Development Goal 7: Affordable and Clean Energy

SDG 7 — Affordable and Clean Energy

Energy intelligence features that help users shift consumption to cleaner, off-peak windows

EcoScore's methodology is fully aligned with the IPCC Guidelines for National GHG Inventories and the GHG Protocol Corporate Standard — the same frameworks used in World Bank Climate Finance operations and UNFCCC national reporting.
Science Leadership

The person behind the methodology

Aprajita

Aprajita — Co-Founder & Science Lead

Climate specialist with expertise in carbon accounting, climate policy, and sustainable development across emerging economies. Aprajita shapes the science behind every emission factor in EcoScore — ensuring the daily score reflects methodologies trusted by the world's leading climate institutions.

For methodology questions or partnership inquiries: hello@pathshalainc.com