# How do I calculate the GWP of a refrigerant blend like R-404A, R-407C or R-410A?

Canonical: https://senseible.earth/answers/refrigerant-blend-gwp-calculation

Multiply each component's mass fraction by its GWP and add the results. R-404A is 44% R-125, 52% R-143a and 4% R-134a, so its AR6 GWP is 0.44 x 3,740 + 0.52 x 5,810 + 0.04 x 1,530 = 4,728. Use one IPCC report, AR5 or AR6, for every gas.

## Compositions of common blends

Use the nominal composition by mass from ASHRAE Standard 34 or the gas maker's safety data sheet. Fractions must add to 100 percent.

- R-410A: R-32 50%, R-125 50%.
- R-407C: R-32 23%, R-125 25%, R-134a 52%.
- R-404A: R-125 44%, R-143a 52%, R-134a 4%.

## Component GWPs (100-year)

AR5 values are from Working Group I Chapter 8, Table 8.A.1; AR6 values from Chapter 7, Table 7.SM.7.

- R-32 (HFC-32): 677 in AR5, 771 in AR6.
- R-125 (HFC-125): 3,170 in AR5, 3,740 in AR6.
- R-134a (HFC-134a): 1,300 in AR5, 1,530 in AR6.
- R-143a (HFC-143a): 4,800 in AR5, 5,810 in AR6.

## Results for the three blends

- R-410A: AR5 0.5 x 677 + 0.5 x 3,170 = 1,923.5. AR6 2,255.5.
- R-407C: AR5 0.23 x 677 + 0.25 x 3,170 + 0.52 x 1,300 = 155.7 + 792.5 + 676 = 1,624.2. AR6 0.23 x 771 + 0.25 x 3,740 + 0.52 x 1,530 = 177.3 + 935 + 795.6 = 1,907.9.
- R-404A: AR5 0.44 x 3,170 + 0.52 x 4,800 + 0.04 x 1,300 = 1,394.8 + 2,496 + 52 = 3,942.8. AR6 0.44 x 3,740 + 0.52 x 5,810 + 0.04 x 1,530 = 1,645.6 + 3,021.2 + 61.2 = 4,728.0.

## Mistakes to avoid

- Using mole fractions instead of mass fractions. Blend names give mass shares.
- Mixing sets, such as AR4 values from an old label with AR6 values for other gases. Older AR4 based figures, such as 2,088 for R-410A, appear on many labels and quotes.
- Treating a blend that contains R-22 or another HCFC as fully Scope 1. Split it: the HFC share goes in Scope 1 and the HCFC share is reported separately, outside the scope totals.
- Taking a GWP printed on an invoice without checking which IPCC report it comes from.

## Worked example: one year of top-ups at a cold store

- Top-ups: 20 kg of R-404A and 8 kg of R-407C
- AR6: 20 x 4,728.0 + 8 x 1,907.9 = 94,560 + 15,263 = 109,823 kg CO2e, about 109.8 t
- AR5: 20 x 3,942.8 + 8 x 1,624.2 = 78,856 + 12,994 = 91,850 kg CO2e, about 91.8 t
- The AR6 total is about 20 percent higher for the same gas, so name the report you used

## What Senseible does here

Senseible keeps refrigerant service and purchase invoices as evidence and calculates refrigerant CO2e when you give the gas and the kilograms charged into equipment; a gas purchase alone is not counted as leakage. The AR5 or AR6 choice changes only these gas figures, not its fuel and grid CO2 factors.

- [Refrigerant top-up invoice to CO2e](https://senseible.earth/answers/refrigerant-top-up-invoice-to-co2e)
- [AR5 or AR6 GWP: which to use](https://senseible.earth/answers/ar5-vs-ar6-gwp-which-to-use)
- [Does R-22 count in Scope 1?](https://senseible.earth/answers/does-r22-count-in-scope-1)
- [HSN codes for refrigerant gases](https://senseible.earth/answers/hsn-codes-for-refrigerant-gases)

Sources: [IPCC AR6 WG1, Chapter 7 Supplementary Material, Table 7.SM.7 (GWP100)](https://www.ipcc.ch/report/ar6/wg1/), [IPCC AR5 WG1, Chapter 8, Appendix 8.A, Table 8.A.1 (GWP100)](https://www.ipcc.ch), [GHG Protocol Corporate Standard (HFCs in Scope 1; HCFCs reported separately)](https://ghgprotocol.org/corporate-standard)

Last reviewed 2026-10-18.