What it is and how it works
The sensor, the sampling and the readings
Kidde's user guide describes the RAB as a portable radon concentration monitor that tracks the alpha radiation formed as radon decays, using a semiconductor radon sensor. Air reaches the sensor through vents on the sides of the case, which Kidde says let radon diffuse in quickly. There is no pump and no fan.
It takes time to give a number. The screen shows the first reading after 12 hours, with a countdown to that first update, and the reading then updates every 60 minutes. Kidde gives the time to a reliable reading as 12 hours above 6.4 pCi/L, 24 hours between 4.2 and 6.4 pCi/L, and 48 hours below 4.2 pCi/L, so at the levels most homes see, the first two days are a warm-up.
The screen is built around averages. After 12 hours, a short press of the Reset button steps through the averages for the past half day, 1 day, 3 days and 7 days; once it has run for a week, the display cycles through the 1-day, 3-day and 7-day averages every 10 seconds. Kidde also lists an accumulated average among the values it records.
Kidde lists a measurement range of 0.09 to 1,000 pCi/L, and the screen shows pCi/L by default, with a Unit button to switch to Bq/m³. Its data sheet prints the EPA's three bands beside the readings: below 2.0 pCi/L, continue monitoring; 2.0 to 3.9, consider steps to reduce radon; 4.0 or higher, take action to mitigate.
Kidde's guide adds a caution worth knowing for any detector of this kind: at low radon levels the random nature of radon decay means counts vary and two units can differ slightly, so it recommends using an average over 7 days or more. After a high reading, it says residual radon decay products inside the device can take from 24 hours to 3.8 days to decay, so allow 24 to 48 hours after moving it before trusting the number.
Independent evidence
C-NRPP 2024/25, recalls and studies
- C-NRPP 2024/25
- Not included in C-NRPP's 2024/25 evaluation
The Canadian National Radon Proficiency Program's 2024/25 comparison of consumer monitors did not include Kidde Radon Detector (RAB). That is a fact about which devices took part, not a finding about this one: no result from that program exists for it either way.
- Recalls
- No Health Canada recall or advisory names this device.
- Peer-reviewed studies
- We found no peer-reviewed comparison that names this model.
- Notes
- A newer battery-powered monitor on Kidde's US site, not in the product brief; added so its evidence status is on record.
C-NRPP is the Canadian National Radon Proficiency Program. Its 2024/25 results were published in May 2025.
How C-NRPP says to use any consumer monitor
- Leave it in place for at least three months, ideally through the heating season, when indoor radon tends to be highest.
- Put it in a room someone uses for at least four hours a day.
- Decide about fixing your home from the long-term average, not a single day or week.
- If you can only run a monitor for less than 91 days, follow up with a long-term test.
What the manufacturer says
Kidde's own statements, attributed
- Kidde saysKidde states the RAB provides an initial reading in about 12 hours and continuously tracks radon levels.
- Kidde saysKidde states battery life of at least one year with the screen off, under normal conditions, on three AAA batteries.
- Kidde saysKidde states the alarm sounds for 20 seconds every hour once the past day's average radon concentration exceeds 4 pCi/L.
- Kidde saysKidde describes the RAB as detecting the presence of radon, and says it is not intended for the prevention or mitigation of radon.
These are Kidde's own statements, attributed to it. They are not our findings, and we have not tested this product ourselves.
Who it fits
Good fit if, and look elsewhere if
Good fit if
- You want an audible alarm when the daily average passes 4 pCi/L.
- You want a battery detector with a screen and no app, phone or Wi-Fi to set up.
- You want daily, 3-day and 7-day averages shown on the device itself.
- You prefer a radon detector from a maker whose smoke and carbon monoxide alarms you already use.
Look elsewhere if
- You want a device that was itself graded in C-NRPP's 2024/25 evaluation.
- You want a reading within minutes; the first figure takes 12 hours and a reliable one up to 48 hours at lower levels.
- You want a record beyond 7-day averages, or graphs on your phone.
- You need a result for a home sale; check what your state accepts before relying on any consumer detector.
Setup and placement
4 steps
- To start, press and hold the Power button for 3 seconds until the buzzer beeps once and the screen lights. The alarm is on by default; a short press of Mute turns it off or on. To start a new measurement, for example after moving the detector, hold Reset for 3 seconds, which clears the data and begins a new 12-hour cycle.
- Kidde says to place it in the lowest livable level of the home for the most accurate readings, and that it measures radon only at the sensor, so radon may be present in other areas. It is meant for indoor residential use, is not waterproof, and should not be dropped or shaken. Kidde gives a working range of 14 to 113°F with humidity below 90%, non-condensing, and says readings outside that range are not accurate.
- The EPA's general guidance for any radon test adds the details: the lowest lived-in level, a room used regularly but not the kitchen or bathroom, at least 20 inches above the floor, and away from drafts, high heat, high humidity and exterior walls. C-NRPP's advice for consumer monitors is to run one for at least 3 months, preferably in the heating season, and decide on the long-term average.
- Kidde's guide also suggests ventilating for at least 10 minutes when the reading is above 4 pCi/L. Opening windows changes what a detector reads at that moment; it does not fix a radon problem. The EPA's advice is to fix a home with a radon level of 4 pCi/L or more, and Kidde's own page says a certified professional can install a mitigation system.
For where any radon test or monitor should sit in a home, see where to place a radon test.
What is in the box, and what it costs to run
Contents, warranty and running costs
In the box
The detector comes with three AAA batteries included, and Kidde's data sheet lists a 1-year limited warranty. It measures 4.2 by 2.1 by 0.9 inches and weighs 0.27 lb. Kidde's data sheet lists UPC 047871343195 among its ordering codes, which helps match the right product on a shelf.
Running costs
There is no lab fee, app or subscription. The running cost is batteries: three AAA cells, which Kidde says last at least a year in normal conditions. Kidde names Energizer E92 as the replacement, warns against lithium cells and against mixing old and new or different types, and suggests replacing them at least once a year.
Questions people ask
6 questions, answered
How long does the Kidde radon detector take to show a reading?
Kidde says the first reading appears after 12 hours, shown as dashes until then. A reliable reading takes 12 hours above 6.4 pCi/L, 24 hours between 4.2 and 6.4 pCi/L, and 48 hours below 4.2 pCi/L.
Why does my Kidde radon detector beep?
Kidde says it sounds for 20 seconds every hour when the average radon concentration over the past day has exceeded 4 pCi/L, with an icon in the upper left of the screen. A short press of Mute turns the alarm off or on.
Does the Kidde RAB detect carbon monoxide or smoke?
No. Kidde's guide says radon detectors are designed to detect radon gas only, not smoke, fire, carbon monoxide or any other gas. Keep your smoke and carbon monoxide alarms as they are.
Is the Kidde radon detector C-NRPP approved?
It was not included in C-NRPP's 2024/25 consumer monitor evaluation, so there is no C-NRPP result for it either way.
What batteries does it use?
Three AAA batteries, included. Kidde names Energizer E92 for replacements, says not to use lithium cells or mix old and new batteries, and rates battery life at a year or more with the screen off.
Can I switch it to Bq/m³?
Yes. It shows pCi/L by default, and a short press of the Unit button switches between pCi/L and Bq/m³.
What to do next
- See every continuous monitor we coverEach with the same fields and its evidence.Go
- Place it where it countsThe lowest lived-in level, away from drafts, at least 20 inches up.Go
- Read your resultWhat a number in pCi/L means and what the EPA says to do next.Go
- Testing for a home sale?Find radon measurement professionals in our directory.Go