What it is and how it works
The sensor, the sampling and the readings
Aranet's datasheet describes the detector as alpha decay event detection using an ionization chamber, filled by air diffusion. There is no pump: air drifts into a 152 cm³ chamber through a spunbound polyester filter that keeps out radon's decay products, and the sensor counts the alpha particles released as radon decays. The datasheet rates its efficiency at 1 count per minute at 2.7 pCi/L.
The same table says plainly what the sensor does not do: it has no radon and thoron discrimination, so it cannot tell radon from thoron, a related gas. Aranet also warns that the device is sensitive to static electricity, and that rubbing it can briefly add false readings of higher radon, so it is worth handling it gently.
A first number appears about 10 minutes after the batteries go in, and Aranet says it takes 1 hour to reach full measurement accuracy. The Back and Forward buttons move the screen between a 10-minute reading and 24-hour, 7-day and 30-day averages. Aranet states its accuracy for those averages; for the current reading, its datasheet says accuracy depends on the radon concentration.
The screen is E-Ink, which holds its image without power and is the main reason for the long battery life. It shows the radon level, the averaging period, the battery level, the units and the buzzer status, with a colored bar for the radon level: green under 2.7 pCi/L, yellow from 2.7 to 8.1 pCi/L and red above 8.1 pCi/L. Those defaults follow World Health Organization reference levels, and Aranet says you can change the thresholds in the app.
Aranet's calibrated range is 0 to 108.10 pCi/L (0 to 4,000 Bq/m³), at a resolution of 0.02 pCi/L. The device can display values up to 214 pCi/L, but Aranet says the listed accuracy is not guaranteed above its calibrated range. Units switch between pCi/L and Bq/m³ in the device settings. The monitor works on its own; Bluetooth to the Aranet Home app adds history, trend charts and alerts, and the device keeps 30 days of history for the app to collect.
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 Aranet Radon One. 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.
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
Aranet's own statements, attributed
- Aranet saysAranet states an accuracy of ±10% for the 24-hour, 7-day and 30-day averages.
- Aranet saysAranet states that the first reliable measurement comes after 1 hour, and the first reading after 10 minutes.
- Aranet saysAranet states that the monitor runs up to 7 years on 2 AA batteries.
- Aranet saysAranet's datasheet gives extrapolated battery lifetimes of 5.0 years with Bluetooth off and 3.4 years with it on for alkaline AA batteries, and 7.0 and 4.7 years for lithium, for descriptive purposes only.
These are Aranet'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 a monitor that runs on batteries for years, so you can place it anywhere without an outlet.
- You want a reading within an hour, with 24-hour, 7-day and 30-day averages on the screen.
- You want radon only, without paying for other air quality sensors.
- You would rather not put a device on your Wi-Fi network.
Look elsewhere if
- You want a device that was itself graded in C-NRPP's 2024/25 evaluation.
- You want to check readings from away from home; it connects to its app over Bluetooth only.
- You also want temperature and humidity on the same screen.
- You need a result for a home sale; check what your state accepts before relying on any consumer monitor.
Setup and placement
4 steps
- Setup is short: insert the two AA batteries the right way round, press the Accept button, and wait 10 minutes for the first measurement. To pair with the Aranet Home app, choose Pair new device in the app, find the sensor by the device number shown on its screen, and enter the pairing code the sensor displays.
- Aranet's placement advice: the lowest regularly occupied floor, usually a basement or ground-floor living area, at least 20 inches (50 cm) above the floor, away from exterior walls, windows, doors and areas with high airflow, and not in a kitchen, bathroom or laundry room. Keep it out of direct sunlight, which Aranet says can damage the E-Ink display and affect readings, and out of humidity above 85%.
- Because it is portable, you can move it between rooms to compare them. Aranet says to allow at least 24 hours in a new spot before reading the result, and recommends monitoring for 3 months or more, ideally across both heating and non-heating seasons, for a reliable long-term average.
- The EPA's general guidance agrees on the essentials: test the lowest lived-in level, at least 20 inches above the floor, away from drafts, high heat, high humidity and exterior walls. C-NRPP's advice for any consumer monitor is to run it for at least 3 months, preferably in the heating season, in a room occupied for at least 4 hours a day.
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
Aranet's datasheet lists two AA alkaline batteries in the package with the monitor. The monitor measures 4.13 by 3.15 by 2.80 inches, weighs 7.8 oz with batteries, has a polycarbonate case rated IP20, and comes with a white, green, yellow or red front panel.
Running costs
There is no lab fee and the Aranet Home app is free. The ongoing cost is two AA batteries; Aranet says lithium cells last longer than alkaline in its own extrapolation, and that turning Bluetooth on shortens battery life, as does its extended Bluetooth range setting. There is no subscription.
Questions people ask
6 questions, answered
Is the Aranet Radon One 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. Aranet's other radon monitor, the Radon Plus, was approved in that evaluation under the name Aranet RN+.
How is it different from the Aranet Radon Plus?
Both use an ionization chamber and an E-Ink screen on two AA batteries. The Radon Plus also measures temperature, humidity and air pressure, and Aranet states ±8% for its averages against ±10% for the Radon One. Only the Radon Plus took part in C-NRPP's 2024/25 evaluation.
How soon does it show a reading?
Aranet says the first measurement appears after 10 minutes and that full accuracy takes 1 hour. The 24-hour, 7-day and 30-day averages build up as the device runs.
Does it need Wi-Fi?
No. Aranet says it measures and displays radon entirely on its own. Bluetooth links it to the Aranet Home app on a phone nearby for history, trend charts and alerts.
How long do the batteries last?
Aranet's product page says up to 7 years on two AA batteries. Its datasheet breaks that down by extrapolation: 5.0 years with Bluetooth off and 3.4 years with it on for alkaline cells, and 7.0 and 4.7 years for lithium, and says the figures are descriptive, not a guarantee.
What do the green, yellow and red bars mean?
By default, green is under 2.7 pCi/L, yellow is 2.7 to 8.1 pCi/L and red is above 8.1 pCi/L, following World Health Organization reference levels. The EPA's guidance in the United States is to fix a home at 4 pCi/L or more and to consider fixing between 2 and 4 pCi/L, so compare the long-term average with those figures too.
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