Radon test kits we recommend

Radon is a colorless, odorless radioactive gas that seeps up from soil and rock, and testing is the only way to know how much is in a home. For most homeowners, the short answer is to start with an inexpensive short-term charcoal kit placed in the lowest lived-in level, then confirm any high result with a second test. This page explains the kit types, how to test correctly and what the numbers mean. The product buttons below go to Amazon, where you can check the live price and current availability.

Short-term, long-term and continuous radon tests

Home radon tests fall into three broad groups, and the right one depends on how fast an answer is needed and how much the result has to be trusted.

• Short-term charcoal kits (2 to 7 days). A small canister or envelope of activated charcoal absorbs radon from the air while it sits in the home. After the exposure period, the kit is sealed and mailed to a lab, which measures the radon decay products and reports a level in picocuries per liter (pCi/L). These are the most common and least expensive kits, and they are a sensible first screening test.
• Long-term alpha-track kits (90 days or more). An alpha-track detector holds a small piece of plastic film that records tiny damage tracks from alpha particles released as radon decays. Because radon levels swing with weather, season and how the house is used, a test that runs three months to a year gives a much better picture of the year-round average. Long-term detectors also go to a lab for analysis.
• Continuous digital monitors. Electronic monitors sample air continuously and show readings on a display or in an app, usually as short-term and long-term averages. Consumer models suit homeowners who want ongoing tracking, for example after a mitigation system is installed. Professional continuous radon monitors are calibrated instruments that log hourly data and can flag tampering, which is why they are standard in real-estate testing.

Short-term tests answer "is there likely a problem?" quickly. Long-term tests answer "what is the true average exposure?" Many homeowners use both: a charcoal kit first, then an alpha-track kit or a follow-up short-term test to confirm.

How to test correctly

Radon kits are simple, but small setup mistakes can skew the result. Every kit comes with its own instructions, and those take priority, but most follow the same basic rules.

• Test the lowest lived-in level. Place the kit in the lowest level of the home that is used regularly, such as a finished basement or a ground-floor bedroom or living room. Skip kitchens, bathrooms, laundry rooms and closets, where humidity and air movement can distort the reading.
• Position the kit properly. Most instructions call for placing the kit at least 20 inches above the floor, away from exterior walls, windows, vents, fans and direct sunlight, in a spot where it will not be disturbed.
• Keep closed-house conditions for short-term tests. Keep windows and exterior doors closed, except for normal coming and going, for at least 12 hours before the test starts and for the full test period. Normal heating and central air can run, but window fans and whole-house fans that bring in outside air should stay off.
• Avoid severe weather. Strong storms and high winds can push short-term results up or down, so many kits recommend not testing during them.
• Record and mail promptly. Write down the start and end dates and times exactly, seal the kit as directed and mail it to the lab right away. Charcoal kits have a limited window between sealing and analysis, and a late arrival can void the result.

Long-term alpha-track tests do not require closed-house conditions; they are meant to capture normal living patterns over the months they run.

Lab fees, turnaround and what to look for

Most do-it-yourself kits are passive devices that need lab analysis. Some kits include the lab fee and return postage in the purchase; others charge the lab fee separately when the kit is sent in. Read the listing and the package carefully so there is no surprise at the mailing stage. Results typically come back by email or online within a week or two of the lab receiving the kit, though timing varies by lab and by season.

Test type	Test length	Best for	Notes
Short-term charcoal kit	2 to 7 days	A quick first screening; follow-up testing	Needs closed-house conditions; mail to the lab promptly; check whether the lab fee is included
Long-term alpha-track kit	90 days to 1 year	Confirming a borderline result; estimating the annual average	Captures seasonal swings; slower answer; lab analysis required
Consumer digital monitor	Ongoing	Tracking trends, checking a mitigation system	No lab step; readings settle over days; useful as a companion to lab tests
Professional continuous monitor	Usually 48 hours or more	Real-estate transactions	Run by a certified tester; hourly data and tamper checks; a service, not a retail purchase

Before buying, check that the kit is analyzed by a lab that participates in a recognized radon proficiency program, that the instructions are clear about test length and placement, and whether the price covers analysis and return postage. Some state radon programs also distribute free or discounted kits, so it is worth checking with the state health department first.

Understanding results and when to act

The EPA recommends fixing a home when the radon level is 4 pCi/L or higher, and suggests considering a fix for levels between 2 and 4 pCi/L, since there is no known safe level of radon exposure. Radon is the leading cause of lung cancer among people who do not smoke, and the risk rises with both the level and the length of exposure.

• Below 2 pCi/L: generally no action needed, though retesting every few years and after major renovations is reasonable.
• Between 2 and 4 pCi/L: consider a long-term test to get a better annual average, and consider mitigation, especially if people spend a lot of time on the lowest level.
• 4 pCi/L or higher on a short-term test: run a follow-up test. A long-term test gives the best picture of the annual average; a second short-term test gives a faster answer. If the follow-up also comes back at or above 4 pCi/L, plan for mitigation.

Mitigation is usually done by a qualified radon contractor, most often with a sub-slab depressurization system: a pipe and fan that draw radon from beneath the foundation and vent it above the roofline. After installation, retest to confirm the system is working, and repeat testing periodically.

Location matters too. Colorado is one of the higher-radon states, with most of its counties in the EPA's highest-potential radon zone, and the state health department encourages every home to be tested. Even so, neighboring houses can test very differently, so a neighbor's result is not a substitute for testing your own home.

For a real-estate sale, buyers and sellers usually rely on a professional radon test rather than a mail-in kit. A certified tester typically places a continuous monitor for at least 48 hours, which gives a fast, documented result that fits inspection deadlines. Homeowners who are not in a transaction can start with a kit and bring in a professional if results are high.

Our picks in this category

The Pro-Lab RA100 Radon Gas Kit is a short-term mail-in screening kit from a long-established home-test brand. Check the package details for how the lab fee is handled.

The Accustar Alpha Track Long-Term Radon Test is an alpha-track detector designed to run for 90 days or more, a good fit for confirming a borderline short-term result or estimating the annual average.

The Health Metric Radon Test Kit is a simple do-it-yourself test that is placed in the home and returned to a lab, suited to homeowners who want an easy first reading.

The First Alert RD1 Radon Test Kit is a widely stocked short-term charcoal kit from a familiar safety brand; the lab fee is typically paid separately when the kit is mailed in, so factor that in.

The AirChek Charcoal Radon Test Kit is a short-term charcoal canister kit that is mailed to the company's lab after exposure, a practical choice for a quick screening test or a follow-up.

Related guides

For an overview of every test format, start with radon test kits: types, use and action levels, and see how a radon test kit works for the science behind charcoal and alpha-track detectors. The guide to what is in a radon test kit walks through the contents of a typical box.

Homeowners comparing brands can read the best radon test kit comparison guide and the First Alert radon test kit guide. For the slower but more accurate route, see long-term radon testing and the annual average and the best long-term radon test kit guide.

Buyers deciding between a kit and a hired tester should read the professional radon test kit guide. Sourcing questions are covered in where to buy a radon test kit and the guide to free radon test kits. Colorado readers can check radon kits for Colorado homeowners and free radon test kits in Colorado.

References

• EPA: Radon
• EPA: Health Risk of Radon
• EPA: Map of Radon Zones

Frequently asked questions

How long does a radon test kit take?

A short-term charcoal kit usually stays in the home for 2 to 7 days, depending on the kit. A long-term alpha-track kit runs for at least 90 days and can stay out up to a year. After the test, the kit goes to a lab, and results typically arrive within a week or two of the lab receiving it.

Where should a radon test kit be placed?

Put the kit in the lowest level of the home that is regularly lived in, such as a finished basement or ground-floor living area. Most instructions call for placing it about 20 inches or more above the floor, away from exterior walls, windows, vents, kitchens and bathrooms. Always follow the specific kit's instructions.

What radon level is considered dangerous?

The EPA recommends fixing a home at 4 pCi/L or higher and suggests considering a fix between 2 and 4 pCi/L. There is no known safe level of radon, so lower is better. Confirm a high short-term result with a follow-up test before deciding on mitigation.

Are home radon test kits accurate?

Kits analyzed by a qualified lab give a reliable reading when the instructions are followed, including placement, closed-house conditions and prompt mailing. Short-term results can vary with weather and season, which is why a high result should be confirmed with a second test, ideally a long-term one.

Should I use a test kit or a professional for a home sale?

Most real-estate radon tests are done by a certified professional with a continuous radon monitor, which produces a documented result within a few days and fits inspection timelines. A mail-in kit is a good option for homeowners who are not in a transaction or who want an initial screening.