EPA 608 leak rate calculator
Three numbers from the ticket, one percentage per year, checked against the threshold for that equipment class. Every step is on this page, so a spreadsheet gets you the same answer. No email required.
What you get
5 things that decide this
- 01A leak rate as EPA defines it: the percentage of the appliance's full charge that would be lost over 12 months if the current rate of loss continued.
- 02Both results side by side: the annualizing method, which scales one top-up by the days since the last one, and the rolling-average method, which sums every top-up in the last 365 days.
- 03A plain verdict against the threshold: 10 percent for comfort cooling and other appliances, 20 percent for commercial refrigeration, 30 percent for industrial process refrigeration.
- 04It will not tell you whether the appliance is covered. That depends on full charge (50 pounds under Section 608, 15 pounds for HFCs under the AIM Act) and the refrigerant, which you confirm against the rule.
- 05A low number is a real result. It means the paperwork, not the leak, is what to fix next.
How the calculator works
The EPA 608 leak rate calculator takes three inputs: pounds of refrigerant added to return the appliance to full charge, the appliance's full charge in pounds, and the number of days since refrigerant was last added. A fourth input, the equipment class, picks the threshold. Its arithmetic is copied from the definition of leak rate in 40 CFR 82.152, which EPA's AIM Act rules in 40 CFR part 84 reuse.
Full charge is the input people get wrong. EPA accepts four ways to set it: the manufacturer's figure, a calculation from component sizes and piping volume, actual measurements of refrigerant added or evacuated, or the midpoint of an established range. Use one method per appliance and write it down, because the record has to show how you got the number.
Out comes a percentage per year and a comparison to the threshold. Nothing is stored, and no email is asked for.
EPA's four steps, as the calculator runs them
This is the method in 40 CFR 82.152, step for step. Use it when one leak event led to one top-up, or several top-ups for the same leak.
- 01
Divide pounds added by full charge
Take the pounds of refrigerant added to bring the appliance back to full charge. If several additions fixed the same leak, add them together. Divide by the pounds the appliance normally holds at full charge.
- 02
Work out the fraction of a year
Count the days since refrigerant was last added. If that's more than 365, use 365. Then divide by 365.
- 03
Divide step one by step two
This scales the top-up to a full year. A top-up after six months counts double; a top-up after a full year counts once.
- 04
Multiply by 100
You now have the leak rate as a percentage of full charge per year. Compare it to the threshold for the equipment class.
The leak rate that starts the 30-day clock
Same three thresholds under both rulebooks. What differs is which appliances are covered.
| Equipment class | Threshold (percent of full charge per year) | Covered under Section 608 | Covered under the AIM Act, from January 1, 2026 |
|---|---|---|---|
| Comfort cooling and other appliances | 10 percent | Full charge of 50 pounds or more of ozone-depleting refrigerant | Full charge of 15 pounds or more of an HFC or a substitute with a GWP above 53 |
| Commercial refrigeration | 20 percent | Full charge of 50 pounds or more | Full charge of 15 pounds or more, same GWP test |
| Industrial process refrigeration | 30 percent | Full charge of 50 pounds or more; 120 days to repair if a shutdown is needed | Full charge of 15 pounds or more; same 120-day shutdown allowance |
Two worked examples
A rooftop unit holds 100 pounds and is comfort cooling. Your tech adds 15 pounds, 180 days after the last top-up. First, 15 divided by 100 is 0.15. Next, 180 divided by 365 is 0.49. Then 0.15 divided by 0.49 is about 0.30, which is 30 percent a year. Comfort cooling's threshold is 10 percent, so the clock is running.
A supermarket rack holds 400 pounds and is commercial refrigeration. Over the last 365 days it took three top-ups totalling 60 pounds. Under the rolling-average method, 60 divided by 400 is 0.15, so 15 percent a year. Commercial refrigeration's threshold is 20 percent, so no repair clock, but a rack losing that much is worth a leak check before the next season.
Notice what the first example shows. Fifteen pounds sounds small against a hundred. Scaled to a year, it's three times the limit. That's why leak rates worked out in someone's head at year end are the usual audit failure.
- Pounds addedRead off the service ticket.
- Full chargeOne of EPA's four methods, recorded.
- Days since last chargeCapped at 365.
- Leak rateAnnualized and rolling, both shown.
- Threshold10, 20 or 30 percent by class.
- VerdictUnder, or the 30-day clock has started.
When the software runs this at ticket close instead of at audit time, the clock becomes visible on the day it starts.
Run it against a real quarter of your tickets
A free scoping call. Bring one quarter of leak-inspection paperwork; we bring the arithmetic and the 2026 rule changes. Where we'd need to go into an existing codebase to build, a paid two-week diagnostic comes first and the fixed price comes out of it.
Questions, answered
01Which method should I use, annualizing or rolling average?+
Either is allowed; the rule lets the owner or operator choose, and the record shows which was used. Annualizing is the natural fit right after a single top-up. Rolling average smooths several small additions across a year. A shop that keeps both has the answer whichever way an inspector asks.
02When does the 30-day repair clock start?+
On the date the calculated leak rate exceeds the threshold, not the date someone in the office notices. Repairs and the initial verification test are due within 30 days, or 120 days where an industrial process shutdown is required. A follow-up verification test is then due within 10 days of the initial test or of the appliance returning to normal operating conditions.
03Does a small system need this at all?+
Under Section 608, leak-repair rules cover appliances with a full charge of 50 pounds or more of ozone-depleting refrigerant. Since January 1, 2026, EPA's AIM Act rules extend leak repair to appliances holding 15 pounds or more of an HFC or a substitute with a GWP above 53. Below those sizes the venting ban and certification rules still apply, but the leak-rate math doesn't drive a deadline.
04How long do I keep the calculation?+
At least three years from the service event. Your record should show the full charge and how it was set, the refrigerant added, the method and result of the leak-rate calculation, and any repair and verification test dates. That's the file an EPA request asks for.
Related
- Refrigerant compliance software for HVAC and refrigeration contractors →The layer that runs this arithmetic at ticket close.
- What is EPA Section 608 compliance? →Defines the rule, plainly.
- Software for HVAC companies →Everything else we build for the trade.
- Missed-call cost calculator →Our other trades calculator, same no-email rule.
