How does the calculator convert lb CO2e/MWh to kg CO2e/kWh?

By international definition (NIST Handbook 44), 1 avoirdupois pound equals exactly 0.45359237 kg. Since 1 MWh = 1,000 kWh, 1 lb/MWh = 0.45359237 / 1,000 = 0.00045359237 kg/kWh. Entering 1,000 lb/MWh normalizes to 0.453592 kg CO2e/kWh.

What is the difference between Location-based and Market-based Scope 2 accounting?

Under GHG Protocol Scope 2 Guidance, the location-based method reflects average emissions intensity of grids on which energy consumption occurs (using regional grid averages such as EPA eGRID). The market-based method reflects emissions from electricity that companies have purposefully chosen (via supplier contracts, EACs/RECs, or green power tariffs).

Why does this tool require entering an emission factor instead of using static country defaults?

Grid emission intensities change annually as generation mixes evolve. Static undated country presets frequently lead to severe accounting inaccuracies and compliance failure. Always reference current primary datasets such as EPA eGRID (US) or DESNZ/DEFRA (UK).

How do I convert kWh of electricity to tonnes of CO2?

Multiply kWh by the emission factor in kg CO2e/kWh, then divide by 1,000. For example, 12,000 kWh a year at an example factor of 0.4 kg CO2e/kWh is 12,000 × 0.4 ÷ 1,000 = 4.8 tonnes CO2e. If your factor is in lb/MWh, multiply it by 0.00045359237 to get kg/kWh first: 800 lb/MWh is about 0.363 kg/kWh.

How much CO2 does 1 kWh of electricity produce?

Exactly the emission factor of the grid or contract that supplied it, so 1 kWh at 0.4 kg CO2e/kWh is 0.4 kg. Factors range from a few tens of grams per kWh on hydro- or nuclear-heavy grids to more than 0.7 kg per kWh on coal-heavy grids, and they change every year, which is why this tool asks for a current published factor.

What is the CO2 emission factor for US electricity?

EPA eGRID2023, the latest edition (data year 2023, revision 2 of June 2025), gives a US average total output rate of 770.884 lb CO2e/MWh, which is 0.3497 kg CO2e/kWh. Regional rates range from 242.8 lb/MWh in Upstate New York (NYUP) to 1,548.5 lb/MWh in Puerto Rico (PRMS); the table on this page lists all 27 subregions.

Which eGRID subregion am I in?

eGRID subregions follow power-grid operating areas, not state lines, so one state can span two or three. Enter your ZIP code in EPA Power Profiler to find your subregion, then select it here. Examples: most of California is CAMX, most of Texas is ERCT, and New York City is NYCW.

How much CO2 does a 100-watt device produce in a day?

A 100 W device running 24 hours uses 100 × 24 ÷ 1,000 = 2.4 kWh. At the US average of 0.3497 kg CO2e/kWh that is about 0.84 kg (1.85 lb) of CO2e per day, or roughly 306 kg a year. Use the appliance helper to convert watts and hours into kWh.

What is the exact conversion between metric tonnes and US short tons?

One metric tonne (t) is exactly 1,000 kg (approx. 2,204.62 lb). One US short ton is exactly 2,000 lb (approx. 907.185 kg). Both are computed directly to ensure compliance across US customary and international ESG reporting formats.

Electricity Carbon Calculator

Convert kWh to CO2e with your US eGRID2023 region or any grid factor in kg/kWh or lb/MWh, and get kg, tonnes, lb, short tons and car-mile equivalents.

kg CO2e = kWh × emission factor (kg CO2e per kWh), and tonnes = kg ÷ 1,000.

Electricity Input & Emission Factor

Electricity Consumption (kWh)

Utility bill or meter consumption (max 1,000,000 kWh).

Estimate kWh from an appliance's watts

Power (W)

Hours/day

Days

kWh = watts × hours per day × days ÷ 1,000.

Time Period

Monthly Annual

US grid region (EPA eGRID2023)

Total output CO2e rates, data year 2023 (eGRID2023 rev. 2, June 2025). Find your subregion by ZIP code with EPA Power Profiler.

Emission Factor

Accepts verified regional or supplier factors up to 10 kg CO2e/kWh normalized.

GHG Protocol Scope 2 Method

Factor Source & Year (Audit record)

Enter electricity usage and factor above, then click Calculate to generate your auditable greenhouse gas calculation.

Estimated Electricity Emissions

0 kg CO2e / 0 lb CO2e

•

Normalized Factor

Calculation Audit Trail

Daily Average

0 kg CO2e / 0 lb

Daily rate

Annualized Total

0 kg CO2e / 0 lb

Annual rate

Roughly equivalent to (EPA equivalencies)

0 miles driven by an average gasoline car

0 gallons of gasoline burned

Uses 3.93 × 10^-4 t CO2e per mile and 8.887 × 10^-3 t CO2 per gallon from the EPA Greenhouse Gas Equivalencies references (2022 vehicle data). For context only, not for inventory reporting.

Factual Standards & Reporting Boundaries

Standard NIST Unit Equivalencies: 1 international avoirdupois pound (lb) = 0.45359237 kg exactly. 1 metric tonne (t) = 1,000 kg (2,204.6226 lb). 1 US short ton = 2,000 lb (907.18474 kg). 1 MWh = 1,000 kWh.

Scope 2 Dual Reporting: The GHG Protocol requires reporting both Location-based (regional average generation mix) and Market-based (contractual instruments including RECs, GOs, or utility green tariffs) figures. Neither method should be conflated.

Avoided Generation vs Inventory: Total-output emission rates (e.g. standard EPA eGRID subregion tables) measure corporate inventory footprint. Avoided-generation assessments (such as installing rooftop solar or energy efficiency retrofits) typically utilize non-baseload marginal rates.

Primary Source Datasets: Retrieve updated factors directly from EPA eGRID (US), UK DESNZ/DEFRA (UK), or your utility supplier.

Data Integrity Note: All math is computed entirely within your browser. Calculations do not transmit proprietary facility or utility data across networks.

US Electricity Emission Factors by eGRID Subregion (2023 data)

Location-based total output emission rates from EPA eGRID2023 (revision 2, released June 12, 2025), the latest edition published by EPA as of October 2026. kg/kWh = lb/MWh × 0.45359237 ÷ 1,000. Rates are at the point of generation and exclude transmission and distribution losses.

Subregion	lb CO2e/MWh	kg CO2e/kWh	kg per 1,000 kWh
NYUP NPCC Upstate NY	242.776	0.1101	110.1
CAMX WECC California	429.983	0.1950	195.0
AKMS ASCC Miscellaneous	522.400	0.2370	237.0
NEWE NPCC New England	543.178	0.2464	246.4
SRVC SERC Virginia/Carolina	596.326	0.2705	270.5
RFCE RFC East	599.170	0.2718	271.8
NWPP WECC Northwest	635.267	0.2882	288.2
AZNM WECC Southwest	706.189	0.3203	320.3
ERCT ERCOT All	736.629	0.3341	334.1
SRMV SERC Mississippi Valley	741.741	0.3364	336.4
U.S. average	770.884	0.3497	349.7
FRCC FRCC All	784.785	0.3560	356.0
SRSO SERC South	846.007	0.3837	383.7
NYCW NPCC NYC/Westchester	865.744	0.3927	392.7
SPNO SPP North	867.740	0.3936	393.6
SPSO SPP South	875.567	0.3972	397.2
SRTV SERC Tennessee Valley	903.306	0.4097	409.7
AKGD ASCC Alaska Grid	905.109	0.4106	410.6
RFCW RFC West	916.054	0.4155	415.5
MROW MRO West	926.552	0.4203	420.3
RFCM RFC Michigan	975.978	0.4427	442.7
RMPA WECC Rockies	1,042.539	0.4729	472.9
HIMS HICC Miscellaneous	1,133.294	0.5141	514.1
NYLI NPCC Long Island	1,189.333	0.5395	539.5
SRMW SERC Midwest	1,248.582	0.5663	566.3
MROE MRO East	1,404.963	0.6373	637.3
HIOA HICC Oahu	1,498.947	0.6799	679.9
PRMS Puerto Rico Miscellaneous	1,548.530	0.7024	702.4

Source: EPA eGRID Summary Data, Table “Subregion Output Emission Rates”, CO2e column. eGRID subregions follow power-grid boundaries, not state lines; use Power Profiler to find yours. For avoided-emission estimates (solar, efficiency), EPA recommends non-baseload or AVERT marginal rates instead of these averages.

Quick answer

kg CO2e = kWh × emission factor (kg CO2e per kWh), and tonnes = kg ÷ 1,000. There is no single CO2-per-kWh figure: in the US, EPA eGRID2023 rates run from 243 lb/MWh (Upstate New York) to 1,549 lb/MWh (Puerto Rico), with a national average of 770.9 lb/MWh, or 0.3497 kg/kWh.

Example: At the US average of 0.3497 kg CO2e/kWh, 1,000 kWh × 0.3497 = 349.7 kg, which is 0.35 tonnes or about 771 lb of CO2e. In California (CAMX, 0.1950 kg/kWh) the same 1,000 kWh is 195 kg.

Enter your kWh and pick your eGRID region, or type your grid's factor, to get kg, tonnes, lb and short tons, then copy the audit summary.

Summary

This calculator provides auditable Scope 2 greenhouse gas calculations by multiplying electricity use in kilowatt-hours (kWh) by an explicit emission factor, with the EPA eGRID2023 total output CO2e rates for every US subregion built in. In accordance with GHG Protocol Scope 2 Guidance, users can distinguish between location-based and market-based accounting. All figures are reported in both metric units (kg CO2e, metric tonnes) and US customary units (pounds CO2e, short tons) based on NIST standards.

How it works

Enter electricity consumption in kilowatt-hours (kWh) for a monthly or annual billing period.
Pick your US eGRID2023 subregion (or the U.S. average) to fill a location-based factor, or enter any authoritative factor in kg CO2e/kWh or lb CO2e/MWh (for example UK DESNZ or your supplier).
Select the reporting methodology (Location-based grid average, Market-based supplier/contract, or Other).
Optionally document the factor source publication and reporting year for audit records.
View instant dual-unit emissions across metric (kg, tonnes) and US customary (lb, short tons) scales.
Copy the formatted audit calculation directly to clipboard for ESG and corporate reporting.

Use cases

Calculate organizational Scope 2 greenhouse gas inventories for ESG compliance.
Convert EPA eGRID subregion output rates (published in lb CO2e/MWh) without external unit conversions.
Evaluate corporate electricity carbon footprint across location-based and market-based accounting methods.
Audit household or small business electric utility bill carbon impacts with exportable math.

Frequently Asked Questions

Last updated: 2026-10-09 · Reviewed by Nham Vu