How to calculate a refrigerant leak rate

Each time you add refrigerant to a covered appliance you calculate its leak rate. There are two accepted methods. Pick one and use it for every appliance at the facility.

Annualizing method

This projects the loss since the last addition over a full year.

leak rate % = (pounds added ÷ full charge) × (365 ÷ days since last addition) × 100

Example. A system with a 120 lb full charge needs 6 lb added, 90 days after the last addition.

(6 ÷ 120) × (365 ÷ 90) × 100 = 20.3%

For comfort cooling the trigger is 10%, so repair is required. For commercial refrigeration the trigger is 20%, so 20.3% is also over it, just barely.

Rolling average method

This totals what you actually added over the past 12 months.

leak rate % = (pounds added in the last 365 days ÷ full charge) × 100

Example. A 500 lb system has had 60 lb added over the past 365 days.

(60 ÷ 500) × 100 = 12.0%

That is over the 10% comfort cooling trigger, but under the 20% commercial refrigeration trigger.

The first calculation after January 1, 2026

The regulation sets how to start. For your first calculation after January 1, 2026:

Annualizing: use 365 as the number of days since the last refrigerant addition.
Rolling average: use the pounds of refrigerant added since January 1, 2026.

Choosing a method

The annualizing method reacts quickly: a large addition after a short interval gives a high rate. The rolling method smooths out one-off events by looking at a full year, but it can lag when a leak starts. Whichever you choose, apply it to every appliance at the facility.

What to record

Record the date, the pounds added, the full charge, the calculation method and the resulting leak rate. See the records checklist. If the rate is over the trigger, the repair clock starts.

Run the numbers for your system. The calculator handles both methods, shows the repair trigger for your appliance type and the repair deadline, and prints a record for the job file. Nothing you enter is stored.

Open the leak rate calculator

Source: 40 CFR 84.106, Leak repair (also on eCFR). This guide is informational and is not legal advice. Last reviewed October 2026. Check the current regulation and your own records before relying on it.