Refrigerant GWP Rankings
Updated October 3, 2026
Global Warming Potential (GWP) expresses the radiative forcing of a refrigerant relative to CO₂ over a 100-year horizon. The headline value is the one the US EPA uses (see the method note below); the IPCC AR4, AR5 and AR6 columns are the raw assessment-report values. Lower is better.
US regulatory status (GWP-based)
US EPA restricts the manufacture and import of new self-contained residential and light-commercial air conditioners and heat pumps that use a refrigerant with a GWP of 700 or more, effective January 1, 2025 (40 CFR 84.54(a)(1)). Limits for other equipment types differ; see the full section at 40 CFR 84.54.
All refrigerants by GWP
Default sort is descending by the headline 100-year GWP (US EPA basis). Click any column heading to sort; use the filters to narrow to a family or safety class. Columns: Refrigerant · GWP (100-yr, US EPA basis) · AR4 · AR5 · AR6 · Basis.
| AR4 | AR5 | AR6 | Basis | Status | |||||
|---|---|---|---|---|---|---|---|---|---|
| R-1234ze(Z) | HFO (pure) | A2L Lower toxicity, lower flammability | 0 | <1 | not assessed | <1 | 0.315 | IPCC AR5 | — |
| R-1224yd(Z) | HCFO | A1 Lower toxicity, no flame propagation | 0.00012 | 1 | not assessed | not assessed | not assessed | US EPA value, 40 CFR 84.64(b) | — |
| R-1234yf | HFO (pure) | A2L Lower toxicity, lower flammability | 0 | 1 | not assessed | <1 | 0.501 | US EPA value, 40 CFR 84.64(b) | — |
| R-1234ze | HFO (pure) | A2L Lower toxicity, lower flammability | 0 | 1 | not assessed | <1 | 1.37 | US EPA value, 40 CFR 84.64(b) | — |
| R-1234ze(E) | HFO (pure) | A2L Lower toxicity, lower flammability | 0 | 1 | not assessed | <1 | 1.37 | US EPA value, 40 CFR 84.64(b) | — |
| R-600a | Hydrocarbon | A3 Lower toxicity, higher flammability | 0 | 1 | not assessed | not assessed | not assessed | US EPA value, 40 CFR 84.64(b) | — |
| R-717 | Natural | B2L Higher toxicity, lower flammability | 0 | 1 | not assessed | not assessed | not assessed | US EPA Technology Transitions GWP reference table | — |
| R-744 | Natural | A1 Lower toxicity, no flame propagation | 0 | 1 | 1 | 1 | 1 | US EPA Technology Transitions GWP reference table | — |
| R-1270 | Hydrocarbon | A3 Lower toxicity, higher flammability | 0 | 1.8 | not assessed | not assessed | not assessed | US EPA value, 40 CFR 84.64(b) | — |
| R-1336mzz(Z) | HFO (pure) | A1 Lower toxicity, no flame propagation | 0 | 2 | not assessed | 2 | 2.08 | US EPA value, 40 CFR 84.64(b) | — |
| R-514A | HFO blend | B1 Higher toxicity, no flame propagation | 0.00006 | 3 | not assessed | not assessed | not assessed | US EPA Technology Transitions GWP reference table | — |
| R-290 | Hydrocarbon | A3 Lower toxicity, higher flammability | 0 | 3.3 | not assessed | not assessed | 0.02 | US EPA value, 40 CFR 84.64(b) | — |
| R-1150 | Hydrocarbon | A3 Lower toxicity, higher flammability | 0 | 3.7 | not assessed | not assessed | not assessed | US EPA value, 40 CFR 84.64(b) | — |
| R-1233zd(E) | HCFO | A1 Lower toxicity, no flame propagation | 0.00034 | 4 | not assessed | 1 | 3.88 | US EPA value, 40 CFR 84.64(b) | — |
| R-123 | HCFC | B1 Higher toxicity, no flame propagation | 0.02 | 77 | 77 | 79 | 90.4 | IPCC AR4 | ODS — HCFC |
| R-152a | HFC (pure) | A2 Lower toxicity, flammable | 0 | 124 | 124 | 138 | 164 | AIM Act exchange value (IPCC AR4) | AIM Act HFC |
| R-457A | HFC/HFO blend | A2L Lower toxicity, lower flammability | 0 | 137 | not assessed | 139 | 159 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-516A | HFC/HFO blend | A2L Lower toxicity, lower flammability | 0 | 140 | not assessed | 131 | 153 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-454C | HFC/HFO blend | A2L Lower toxicity, lower flammability | 0 | 146 | not assessed | 146 | 166 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-455A | HFC/HFO blend | A2L Lower toxicity, lower flammability | 0 | 146 | not assessed | 146 | 166 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-515B | HFO blend | A1 Lower toxicity, no flame propagation | 0 | 287 | not assessed | 299 | 322 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-515A | HFO blend | A1 Lower toxicity, no flame propagation | 0 | 387 | not assessed | 403 | 433 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-454B | HFC/HFO blend | A2L Lower toxicity, lower flammability | 0 | 465 | not assessed | 467 | 531 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-450A | HFC/HFO blend | A1 Lower toxicity, no flame propagation | 0 | 601 | not assessed | 547 | 643 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-124 | HCFC | A1 Lower toxicity, no flame propagation | 0.022 | 609 | 609 | 527 | 597 | IPCC AR4 | ODS — HCFC |
| R-513A | HFC/HFO blend | A1 Lower toxicity, no flame propagation | 0 | 630 | not assessed | 573 | 673 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-32 | HFC (pure) | A2L Lower toxicity, lower flammability | 0 | 675 | 675 | 677 | 771 | AIM Act exchange value (IPCC AR4) | AIM Act HFC |
| R-452B | HFC/HFO blend | A2L Lower toxicity, lower flammability | 0 | 698 | not assessed | 676 | 779 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-365mfc | HFC (pure) | A2 Lower toxicity, flammable | 0 | 794 | 794 | 804 | 914 | AIM Act exchange value (IPCC AR4) | AIM Act HFC |
| R-245fa | HFC (pure) | B1 Higher toxicity, no flame propagation | 0 | 1,030 | 1,030 | 858 | 962 | AIM Act exchange value (IPCC AR4) | AIM Act HFC |
| R-236ea | HFC (pure) | A1 Lower toxicity, no flame propagation | 0 | 1,370 | 1,370 | 1,330 | 1,500 | AIM Act exchange value (IPCC AR4) | AIM Act HFC |
| R-448A | HFC/HFO blend | A1 Lower toxicity, no flame propagation | 0 | 1,386 | not assessed | 1,273 | 1,494 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-449A | HFC/HFO blend | A1 Lower toxicity, no flame propagation | 0 | 1,396 | not assessed | 1,282 | 1,504 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-134a | HFC (pure) | A1 Lower toxicity, no flame propagation | 0 | 1,430 | 1,430 | 1,300 | 1,530 | AIM Act exchange value (IPCC AR4) | AIM Act HFC |
| R-407C | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 1,774 | 1,774 | 1,624 | 1,908 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-22 | HCFC | A1 Lower toxicity, no flame propagation | 0.055 | 1,810 | 1,810 | 1,760 | 1,960 | IPCC AR4 | ODS — HCFC |
| R-407F | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 1,825 | 1,825 | 1,674 | 1,965 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-410A | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 2,088 | 2,088 | 1,924 | 2,256 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-407A | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 2,107 | 2,107 | 1,923 | 2,262 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-427A | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 2,138 | 2,138 | 2,024 | 2,397 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-452A | HFC/HFO blend | A1 Lower toxicity, no flame propagation | 0 | 2,140 | not assessed | 1,945 | 2,292 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-438A | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 2,265 | not assessed | not assessed | not assessed | computed under 40 CFR 84.64(b) from component values | AIM Act HFC |
| R-417A | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 2,346 | not assessed | not assessed | 2,508 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-422B | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 2,526 | not assessed | not assessed | not assessed | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-421A | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 2,631 | 2,631 | 2,385 | 2,812 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-422D | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 2,729 | not assessed | not assessed | not assessed | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-422A | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 3,143 | not assessed | not assessed | not assessed | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-125 | HFC (pure) | A1 Lower toxicity, no flame propagation | 0 | 3,500 | 3,500 | 3,170 | 3,740 | AIM Act exchange value (IPCC AR4) | AIM Act HFC |
| R-404A | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 3,922 | 3,922 | 3,943 | 4,728 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-507A | HFC blend | A1 Lower toxicity, no flame propagation | 0 | 3,985 | 3,985 | 3,985 | 4,775 | US EPA value, 40 CFR 84.64(b) | AIM Act HFC |
| R-143a | HFC (pure) | A2L Lower toxicity, lower flammability | 0 | 4,470 | 4,470 | 4,800 | 5,810 | AIM Act exchange value (IPCC AR4) | AIM Act HFC |
| R-502 | CFC blend (azeotrope) | A1 Lower toxicity, no flame propagation | 0.33 | 4,657 | 4,657 | 4,786 | 5,872 | IPCC AR4, mass-weighted (incl. CFC/HCFC constituents) | ODS — CFC |
| R-11 | CFC | A1 Lower toxicity, no flame propagation | 1 | 4,750 | 4,750 | 4,660 | 6,230 | IPCC AR4 | ODS — CFC |
| R-500 | CFC blend (azeotrope) | A1 Lower toxicity, no flame propagation | 0.605 | 8,077 | 8,077 | 7,564 | 9,268 | IPCC AR4, mass-weighted (incl. CFC/HCFC constituents) | ODS — CFC·AIM Act HFC |
| R-218 | PFC | A1 Lower toxicity, no flame propagation | 0 | 8,830 | 8,830 | 8,900 | 9,290 | IPCC AR4 | — |
| R-236fa | HFC (pure) | A1 Lower toxicity, no flame propagation | 0 | 9,810 | 9,810 | 8,060 | 8,690 | AIM Act exchange value (IPCC AR4) | AIM Act HFC |
| R-C318 | PFC | A1 Lower toxicity, no flame propagation | 0 | 10,300 | 10,300 | 9,540 | 10,200 | IPCC AR4 | — |
| R-12 | CFC | A1 Lower toxicity, no flame propagation | 1 | 10,900 | 10,900 | 10,200 | 12,500 | IPCC AR4 | ODS — CFC |
| R-13 | CFC | A1 Lower toxicity, no flame propagation | 1 | 14,400 | 14,400 | 13,900 | 16,200 | IPCC AR4 | ODS — CFC |
| R-503 | CFC blend (azeotrope) | A1 Lower toxicity, no flame propagation | 0.599 | 14,560 | 14,560 | 13,299 | 15,558 | IPCC AR4, mass-weighted (incl. CFC/HCFC constituents) | ODS — CFC·AIM Act HFC |
Amber: GWP ≥ 700, the US limit for new residential/light-commercial AC and heat pumps (40 CFR 84.54(a)(1), (c)(1)). Green: GWP < 150. The 0 (CO2 reference) and natural-refrigerant tier dominates the bottom of the table; the CFC/HCFC legacy refrigerants dominate the top.
Status is derived: an AIM Act HFC is one of the 18 regulated HFCs (42 U.S.C. 7675(c)) or a blend containing one. For US 40 CFR 84.54 thresholds the blend GWP is recomputed under 84.64(c), which excludes CFC/HCFC/PFC constituents — so a CFC/HCFC blend's headline (mass-weighted IPCC AR4) is not the value used against those limits.
How the headline GWP is chosen
GWP 100-yr on the basis US EPA uses: regulated HFCs = AIM Act exchange values (40 CFR 84 Appendix A, identical to IPCC AR4); HFOs, HCFOs, hydrocarbons, ammonia, CO2 = 40 CFR 84.64(b) Table 1; CFCs, HCFCs, PFCs = IPCC AR4 Table 2.14. Blends = sum of mass fraction x constituent GWP (40 CFR 84.64(b)), rounded half-up to an integer.
The AR4, AR5 and AR6 columns are the raw IPCC values. A blend gets a value in one of those columns only when every constituent is listed in that report. IPCC AR5 lists some low-GWP fluids as "<1"; that is shown as "<1" for pure substances and counted as 1 in blend sums. Blend headlines are rounded to a whole number.
GWP by refrigerant family
HVAC refrigerants cluster into families with characteristic GWP ranges, tracking the history of transitions: chlorine-bearing CFCs and HCFCs phased out for ozone depletion (Montreal Protocol 1987), then high-GWP HFCs phased down for climate impact (Kigali Amendment 2016, EU F-Gas, AIM Act 2020).
- HCFCs (ozone-depleting): R-22 (1,810), R-123 (77). R-22: US production and import ended January 1, 2020, and service continues from reclaimed stock. R-123: production for servicing existing equipment continues until January 1, 2030.
- HFCs (high-GWP, no ozone depletion): R-410A (2,088), R-134a (1,430), R-404A (3,922), R-507A (3,985). Being phased down under the AIM Act and EU F-Gas Regulation; service supply persists via reclaimed and allocated production.
- HFC/HFO blends (low to medium GWP): R-32 (675), R-454B (465), R-454C (146), R-455A (146), R-448A (1,386), R-449A (1,396), R-513A (630). The A2L/low-GWP new-equipment family.
- HFOs and HCFOs (very low GWP): R-1234yf (1), R-1234ze(E) (1), R-1233zd(E) (4), R-1336mzz(Z) (2). Very low GWP from short atmospheric lifetimes; used in mobile AC and chillers.
- Natural refrigerants (near-zero GWP): R-744 (CO₂, 1 by definition), R-717 (NH₃, 1), R-290 (propane, 3.3), R-1270 (propylene, 1.8), R-600a (isobutane, 1). Used in commercial and industrial refrigeration and small appliances.
US equipment restrictions by category
The AIM Act Technology Transitions rule restricts new equipment by GWP, but the limit and effective date differ by equipment type. Rather than reproduce each figure here (they were revised in 2026), consult the controlling text directly: 40 CFR 84.54. The one limit stated on this page is the residential / light-commercial self-contained AC and heat-pump limit of 700, effective January 1, 2025 (§84.54(a)(1)). Service of existing equipment continues; refrigerant production declines on an allowance schedule rather than being banned outright.
Which assessment report applies?
AIM Act exchange values are the IPCC AR4 values. The EU's 2024 F-gas Regulation uses AR4 for HFCs and AR6 for other fluorinated gases (Regulation (EU) 2024/573, recital 8). Because different regimes cite different reports, this table shows all three IPCC columns alongside the US EPA headline; for a specific regulation, use the value that regulation cites.
Beyond direct GWP — TEWI and LCCP
Total Equivalent Warming Impact (TEWI) and Life Cycle Climate Performance (LCCP) account for both direct refrigerant emissions (leakage, end-of-life) and indirect emissions from energy use over the equipment lifetime. For chillers, the indirect (energy) component typically dominates TEWI by 80–90%, so efficiency can matter more than refrigerant GWP. For higher-leak-rate equipment the balance shifts toward low-GWP refrigerants. GWP alone is necessary but not sufficient for environmental decisions.
Lifetime context — why GWP tracks atmospheric persistence
Atmospheric lifetime is one of the three inputs to GWP (with radiative efficiency and the integration horizon) and often the dominant one. Per IPCC AR5 WG1 Table 8.A.1: HFC-23 has a 222-year lifetime; HFC-125, 28.2 years; HFC-134a, 13.4 years; HFC-32, 5.2 years; HFO-1234yf, 10.5 days. The collapse from HFC-134a to HFO-1234yf comes almost entirely from the shorter atmospheric lifetime — the basis of HFO chemistry.
International regulatory landscape
The Montreal Protocol has 198 parties; 174 of them have ratified the Kigali Amendment (as of August 10, 2026, UNEP Ozone Secretariat). Kigali coordinates an HFC phase-down; the AIM Act and the EU F-Gas Regulation are the regional implementations. Schedules differ by country group and continue to evolve, so check the framework in your jurisdiction for current compliance.