Radon Test Calculator
Schedule a radon test window, keep it inside the heating season when possible, and compare a lab result with the EPA action level.
A long-term radon test started October 1 runs through 2026-12-31; a 5 pCi/L result is above the EPA action level and should follow the EPA action guidance.
How to use it
- Choose a test type. Use a long-term test for the main schedule, or a short-term test for quick screening.
- Pick the start date. Choose when the detector will be placed in the lowest lived-in level of the home.
- Add the lab result if you have it. Enter the pCi/L result only after the lab report comes back.
- Read the schedule and guideline note. Use the test window, retest reminder, and the EPA action wording as planning guidance.
How this works
The calculator uses 91 days for a long-term test, 7 days for a short-term screen, and October through April as the heating-season target window. It then sets a 2-year retest reminder and compares any entered result with the EPA action level.
Sources
Radon test length, closed-house testing advice, the 4.0 pCi/L action level, and the 2 to 4 pCi/L consider-fixing range follow the EPA's Citizen's Guide to Radon and the EPA radon program. Use the lab report and a state-certified radon professional for mitigation decisions.
Radon test questions
When should I start a radon test?
Place a long-term test during the heating season, in the lowest lived-in level of the home, under closed-house conditions. The EPA treats tests longer than 90 days as long-term.
What radon level triggers action in the US?
The EPA action level is 4.0 pCi/L. The EPA recommends fixing your home at or above 4 pCi/L, and suggests considering a fix between 2 and 4 pCi/L.
Can a short-term radon test decide whether to remediate?
A short-term test (2 to 90 days) screens quickly, but the EPA recommends confirming with a long-term test, or a second test, before deciding to mitigate.
How often should I retest for radon?
Retest after major renovations, energy retrofits, foundation work, radon mitigation, or about every 2 years for ongoing checks.
Does this calculator diagnose health risk?
No. It schedules testing and compares a lab result with the EPA action level. It does not diagnose exposure, illness, or individual risk.