What does my radon result mean?

Enter the number from your test kit, lab report or monitor. The checker runs in your browser; nothing you enter is sent to us.

Radon levels at a glance

Result	What it means
Below 2 pCi/Lbelow 74 Bq/m³	Low. No fix needed; retest after big changes to the house.
2 to 4 pCi/L74 to 148 Bq/m³	Below the action level, but the EPA says to consider fixing. Confirm with a long-term test first.
4 pCi/L or more148 Bq/m³ or more	At or above the EPA action level: fix the home. After a short-term test, confirm with a follow-up test first.

US results are in picocuries per liter (pCi/L); most digital monitors and other countries use becquerels per cubic meter (Bq/m³). 1 pCi/L is 37 Bq/m³.

Short-term or long-term test?

A short-term test runs 2 to 7 days and shows the level during that week. Radon rises and falls with weather and seasons, so a long-term test of 90 days or more gives a truer picture of your year-round average. That's why the EPA recommends a follow-up test before fixing a home after a high short-term result.

Does fixing it work?

Yes. Across Pennsylvania, where the state records every installation, the typical level dropped from 7.7 to 1.0 pCi/L after a radon system was installed, and 95% of homes ended up below 4. See what fixing radon costs.

Compare with your area

Every county page has this checker, with the county's own test results to compare against.

Sources

EPA, A Citizen's Guide to Radon: action level, follow-up testing and when to fix.
WHO Handbook on Indoor Radon: reference level of 100 Bq/m³.
National comparison: CDC Environmental Public Health Tracking Network, lab radon tests 2008–2017. Results after mitigation: Pennsylvania DEP mitigation records. See how we know.