Last updated 2026-07-17
Radon testing is the cheapest piece of the whole radon picture — and in New Jersey it’s sometimes free. Here’s what each option actually costs, what the state’s rules allow you to do yourself, and when paying a professional is worth it.
| Test option | Typical cost | Best for |
|---|---|---|
| Free county health department kit | $0 (while supplies last) | Routine screening of your own home |
| DIY charcoal kit (hardware store or certified NJ business) | $15–$50 incl. lab fee | Routine screening, retests |
| Consumer digital radon monitor | $150–$300 one-time | Ongoing tracking, no lab fees |
| Professional short-term test | ~$100–$300 | Real estate deals, documentation |
| Radon test added to a home inspection | ~$90–$250 add-on | Home purchases |
National cost guides put professional radon testing in the $125–$400 range, with continuous-monitor tests in some markets reaching $300–$500 for large homes needing multiple devices. Most standard NJ homes land near the middle of that.
New Jersey requires businesses and professionals that test for or mitigate radon to be certified by the NJDEP Radon Program — but the rules (N.J.A.C. 7:28-27, per N.J.S.A. 26:2D-72) carve out an exception for an individual testing or mitigating a building he or she owns. Testing your own house with a $20 kit is fully allowed.
The classic DIY device is a charcoal canister: you open it, leave it in the lowest lived-in level of the home for 2–7 days, reseal it, and mail it to a lab. Some kits include the lab fee; others charge it separately, so check before buying. NJDEP suggests buying kits from a certified NJ radon business or picking one up at a hardware store — and many municipal and county health departments hand out free kits in partnership with the state (Bergen, Burlington, and Passaic counties have all run programs; supplies are limited).
DIY caveats worth knowing:
A certified measurement professional typically deploys a continuous radon monitor (CRM) — professional-grade equipment (the devices themselves cost inspectors over $1,000) that logs radon hourly for 48+ hours. That buys you three things:
Expect roughly $100–$300 for a standalone professional short-term test in New Jersey. Bundling radon with a general home inspection is usually the cheapest professional route.
If you’re testing a house you’re considering purchasing, NJDEP’s guidance is clear: use the services of a DEP-certified radon tester. The state’s certification law prohibits anyone from testing other people’s buildings for compensation without certification, so a buyer’s radon test in a transaction should always come from a certified measurement business. You can verify any company’s certification through the NJDEP Radon Program (800-648-0394 or njradon.org).
For short-term tests (2–7 days), EPA protocol calls for windows and doors closed — except normal coming and going — for 12 hours before the test starts and for its entire duration. Run the test in the lowest level of the home you use as living space. Winter is the best season to test: the “stack effect” of a heated house pulls more soil gas indoors, which is why NJDEP recommends heating-season testing and marks January as Radon Action Month.
EPA and NJDEP both recommend mitigating at 4.0 pCi/L or higher, and EPA suggests considering fixes between 2 and 4 pCi/L. For context, the average indoor level in U.S. homes is about 1.3 pCi/L and outdoor air averages 0.4 pCi/L. If a short-term DIY test comes back elevated, confirm with a follow-up test before spending mitigation money — and if you’re at or above 4 pCi/L on confirmation, get quotes from NJ-certified mitigation businesses (typically $800–$2,500 for a standard system).
Screen your own home with a free or ~$20 kit; there’s no reason not to. Pay for a certified professional test when a transaction, tenant, or dispute means the result has to stand up to scrutiny — or when you want hourly data you can trust.
Yes. New Jersey's certification rules (N.J.A.C. 7:28-27) include an exception for individuals testing a building they own, so a DIY kit in your own home is perfectly legal. The exception does not extend to testing someone else's building — and if you're testing a home you're buying, NJDEP says to use a certified measurement business.
Plan on roughly $100–$300 for a professional short-term test. Adding radon to a home inspection typically runs about $90–$250 since the inspector is already on site, while a standalone visit with a continuous radon monitor sits at the higher end of the range.
Yes, several county health departments distribute free kits in partnership with NJDEP while supplies last — Bergen, Burlington, and Passaic counties have run programs, among others. Call your municipal or county health department to ask; kits are usually first-come, first-served.
For any short-term test, EPA protocol requires windows and exterior doors to stay closed (except normal entry and exit) for 12 hours before and during the test. Skipping this dilutes indoor air with outdoor air, which averages just 0.4 pCi/L, and can mask a real problem.
EPA recommends retesting about every two years, and also after renovations, foundation work, or adding living space in a basement. Radon levels change over time even when nothing obvious about the house has changed.
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