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Refrigerant Designation Decoder

Type any R-number and read the ASHRAE 34 numbering rules, then the family, composition, safety class, ODP, GWP, glide, and replacements.

Refrigerant numbers are not arbitrary labels. For a single compound the digits count the carbon, hydrogen, and fluorine atoms in the molecule, which is how R-22 reads as one chlorine, one hydrogen, two fluorines (an HCFC) and R-32 reads as a clean HFC. For blends, a 400-series number is zeotropic and a 500-series number is azeotropic, with a trailing letter that pins down the exact composition. The 700 series uses the molar mass, so 744 is CO2. This decoder reads those rules for any R-number, and for the common refrigerants it adds the safety class, ODP, GWP, temperature glide, and the replacement and phasedown context. The property values are reused from ToolGrit's shared refrigerant dataset so they match the P-T chart and the charge and leak tools.

Pro Tip: The safety class is two parts. The letter is toxicity (A is lower, B is higher) and the number is flammability (1 is non-flammable, 2L is mildly flammable, 3 is highly flammable). The newer low-GWP refrigerants like R-32 and R-454B are A2L, which means they are mildly flammable. They are not drop-in safe for equipment built for non-flammable A1 refrigerants, so the charge limits and leak detection in the code apply.

Once you know the refrigerant, look up its saturation pressure on the

Refrigerant P-T Chart →

Check the charge with superheat and subcooling using the

Superheat / Subcooling Calculator →

Adjust line-set charge with the

Refrigerant Charge Calculator →

Estimate the CO2-equivalent of a leak from the GWP with the

Refrigerant Leak Calculator →

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Refrigerant Designation Decoder
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How It Works

  1. Enter the R-number

    Type the designation from the nameplate or cylinder (R-410A, R-32, R-1234yf). Shorthand like CO2 works too.

  2. Read the number breakdown

    The decoder shows how the digits resolve under the ASHRAE 34 rules: the atom counts for a compound, or the blend series and composition letter for a blend.

  3. Check the properties

    For the common refrigerants you get the family, composition, safety class (decoded into toxicity and flammability), ODP, GWP, and glide.

  4. Read the field notes

    Notes cover zeotrope charging, A2L and A3 flammability, CO2 pressure, and what high GWP means for the phasedown.

  5. Verify before a regulated decision

    The numbering rules are exact. Confirm GWP, safety class, and exact blend composition against ASHRAE 34 or the manufacturer SDS before a regulated or safety decision.

Built For

  • An HVAC tech who finds an unfamiliar R-number on a nameplate and needs the safety class and pressure behavior before connecting gauges.
  • A contractor planning an R-22 retrofit who wants to compare R-407C, R-448A, and R-449A.
  • A facility manager estimating the CO2-equivalent exposure of a high-GWP charge for reporting.
  • An apprentice learning why R-454B is mildly flammable but R-410A is not.
  • Anyone confused by why R-410A and R-32 have such different numbers despite both being used in AC.

Features & Capabilities

Decodes any R-number

The ASHRAE 34 numbering rules resolve the atom counts or blend series for any valid number, not just a fixed list.

Safety class broken out

The class is split into toxicity (A/B) and flammability (1/2L/2/3) with plain-English meaning.

Consistent property data

GWP, ODP, and composition are reused from the same dataset as the rest of the site's refrigerant tools.

Replacement and phasedown context

For common refrigerants the tool states what it replaces, what replaces it, and where it sits in the HFC phasedown.

Comparison

R-number Family Safety class GWP Glide Note
R-22 HCFC A1 1810 None Legacy; production phased out 2020
R-410A HFC blend A1 2088 Negligible Residential AC; being phased down
R-32 HFC A2L 675 None Low-GWP A2L, mildly flammable
R-454B HFO/HFC blend A2L 466 ~1 F R-410A replacement, A2L
R-1234yf HFO A2L 1 None Automotive R-134a replacement
R-744 Inorganic (CO2) A1 1 None Natural; very high pressure

References

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Frequently Asked Questions

R-410A is a near-azeotropic HFC blend of R-32 and R-125 in a 50/50 ratio. The 4 marks it as a blend (400 series), and the trailing A identifies the specific composition among blends of those components. It is safety class A1 (non-flammable, lower toxicity), has zero ozone depletion potential, and a 100-year GWP around 2088. It replaced R-22 in residential AC and is now being phased down in favor of A2L options like R-454B and R-32.
For a single compound, the ones digit is the number of fluorine atoms, the tens digit is the number of hydrogen atoms plus one, and the hundreds digit is the number of carbon atoms minus one (omitted when zero). Chlorine fills whatever bonds are left. So R-134a is two carbons, two hydrogens, four fluorines, no chlorine, which makes it an HFC. R-22 works out to one carbon, one hydrogen, two fluorines, one chlorine, which makes it an HCFC.
The letter is toxicity and the number is flammability. A is lower toxicity, B is higher toxicity. 1 means no flame propagation (non-flammable), 2L means mildly flammable with a low burning velocity, 2 means flammable, and 3 means highly flammable. So A2L (R-32, R-454B) is lower toxicity and mildly flammable, while A3 (propane, R-290) is lower toxicity but highly flammable.
A zeotropic blend boils and condenses over a range of temperatures rather than at one point, which is the glide. The components also evaporate at different rates, so if you charge vapor or top off after a leak, the composition that stays in the system drifts (fractionation). Always charge a zeotrope from the liquid side, and on a significant leak recover and recharge rather than topping off.
GWP (Global Warming Potential) compares a gas to CO2 over 100 years, with CO2 set to 1. R-404A has a GWP near 3922, meaning a pound of it leaked has roughly 3922 times the warming effect of a pound of CO2. The AIM Act phasedown targets high-GWP HFCs, which is why lower-GWP A2L refrigerants and natural refrigerants like CO2 (R-744) are replacing them.
Disclaimer: Properties, safety classifications, and application notes returned by this decoder are reference values and vary by source, blend formulation, and standard edition (ASHRAE 34). Glide, flammability class (A1/A2L/A3), operating pressures, and material compatibility must be confirmed for the specific equipment and jurisdiction, and refrigerant handling is regulated. Use this tool to understand a designation, not to select or charge a system; always verify against the manufacturer's specifications, the refrigerant safety data sheet, and applicable codes. This tool is for educational and reference purposes only and is not a substitute for an EPA-certified technician.

Learn More

HVAC

Refrigerant Numbers Explained

How the R-number system works: what the digits mean for single compounds, how blends get their 400 and 500 series numbers, the safety class letters, and what ODP, GWP, and glide tell you.

Read Guide →

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