StamparioRefrigerant leak rate calculator
The annualizing method divides the refrigerant added by the appliance’s full charge, multiplies by 365 divided by the days since the last addition (365 if longer), and multiplies by 100. For example, 4.5 lb added to a 28 lb system 120 days after the last top-up is a 48.9% annual leak rate. EPA’s leak-repair rules use thresholds of 10% for comfort cooling, 20% for commercial refrigeration and 30% for industrial process refrigeration.
Above the 20% leak-rate threshold for this appliance type. Repair rules apply to covered appliances.
Thresholds apply to covered appliances: 50 lb+ of ozone-depleting refrigerant, or 15 lb+ of HFCs from 2026. Check the rule for your equipment.When you need it
Owners of appliances with 50 lb or more of an ozone-depleting refrigerant (40 CFR 82.157), and from 2026 appliances with 15 lb or more of an HFC or substitute (40 CFR 84.106), must calculate the leak rate every time refrigerant is added. The technician’s service record gives them the numbers.
How it works
- Refrigerant added this time, in pounds
- The appliance’s full charge
- Days since the last time refrigerant was added (365 if longer, or if this is the first time)
The other allowed method, the rolling average, looks at all refrigerant added over the past 365 days instead. Write the method you used on the record.
Common questions
What if it’s the first time refrigerant is added?
Use 365 days. The annualizing method caps the period at one year.
Does this apply to a house AC?
Usually not: typical residential systems are below the 50 lb (ozone-depleting) and 15 lb (HFC) sizes the rules cover. The calculation still tells you how fast it is leaking.
Sources
- 40 CFR 82.152, definitions (leak rate)
- 40 CFR 82.157, appliance maintenance and leak repair
- 40 CFR 84.106, HFC leak repair (from 2026)
Codes change by edition and the authority having jurisdiction (your fire marshal, water purveyor or state agency) decides which rules apply. This page is general information, not legal advice.