MurmeliBaby monitors and radiation: how much distance do you need?
Based on current knowledge, the radiation from a baby monitor is no reason to worry. The Swiss Federal Office of Public Health (FOPH) had baby monitors measured: at a distance of one metre, the values are far below the limits. According to the FOPH, this explicitly also applies to a phone used as a baby monitor. If you want to take extra precautions, a few simple steps are enough, and most of them take a moment with a baby monitor app.
This guide comes from the team behind the baby monitor app Murmeli. The figures are taken from the FOPH fact sheet on baby monitors dated 1 March 2026 and from the pages of the German Federal Office for Radiation Protection (BfS). We did not take any measurements ourselves.
What the FOPH measured
The measurements the FOPH relies on come from a 2005 study by the IT'IS Foundation and, according to the fact sheet, still represent the state of knowledge. The worst case was measured: the devices were exposed to a continuous tone so that they transmitted without a break.
The result shows how quickly radiation drops with distance. For the strongest of the three devices, a 500 milliwatt baby monitor, the electric field fell from 41.6 volts per metre at 5 centimetres to 8.5 V/m at 20 centimetres and to 3.2 V/m at one metre. The reference level for this device is 29 V/m. A 10 milliwatt device reached 0.43 V/m at one metre, against a reference level of 40 V/m.
Even right next to the device, the radiation actually absorbed by the body stayed far below the limit. This specific absorption rate was 0.01 and 0.08 watts per kilogram, while the limit is 2 W/kg. For ten newer devices from 2020 onwards, the FOPH analysed test reports from the US telecommunications authority (FCC): on average they stayed below a quarter of the US limit, and none exceeded it. According to the FOPH, baby monitors comply with the limit even if the child were to touch the device while it is running.
The FOPH still recommends some precaution, because the limits cover the proven short-term effects and less is known about very long periods. These recommendations are easy to follow.
How strongly do different baby monitors transmit?
Baby monitors transmit on different frequencies and with different power. The FOPH lists these maximum values:
| Frequency | Max. transmit power | Range according to manufacturer |
|---|---|---|
| 27 MHz | 100 mW | 400 m |
| 40.7 MHz | 10 mW | 150 m |
| 446 MHz (walkie-talkie) | 500 mW | 5000 m |
| 865 MHz | 10 mW | 400 m |
| 1900 MHz (DECT) | 250 mW | 300 m |
| 2400 MHz | 10 mW | 300 m |
According to the BfS, a Wi-Fi device may transmit at no more than 100 milliwatts in the 2.4 GHz band, which is less than half of what a DECT baby monitor is allowed. A phone running as a baby monitor over Wi-Fi is therefore at the lower end of this table. Walkie-talkies have the highest power, which is why the FOPH does not recommend them as a low-radiation baby monitor.
Some radio baby monitors have automatic voice activation, called VOX. They only transmit when the room gets louder. This is an extra precaution, not a requirement: according to the FOPH, devices that transmit continuously also stay below the limits. During video transmission every system transmits without a break, so it pays to turn the picture on only when you need it.
How far from the cot?
The FOPH recommends placing the baby unit at least one metre from the cot. The BfS advises the largest distance at which the device still works reliably.
With a phone that is easy. It sits on a chest of drawers, a shelf or a table next to the cot, and from there the camera usually has a better view of your child than from up close. Neither a phone nor a baby monitor belongs in the cot or against the bars. The measurements above show why a few decimetres already make a big difference: between 5 and 20 centimetres, the field of the strongest device dropped to a fifth.
Once it is set up, check once that the baby monitor hears your child well: speak quietly next to the cot and listen to what arrives on the parent device.
The power adapter needs its own distance
A plug-in power adapter creates a low-frequency magnetic field. According to the FOPH, it often contains a cheap transformer that produces a stronger field in its immediate surroundings. At 50 centimetres this field is already very small. The FOPH therefore recommends 50 centimetres between the adapter and the cot.
This also applies to the phone charger. The socket and the charger should not be right next to the cot; a longer cable usually solves it.
A phone as a baby monitor: safe and easy to set up
The FOPH covers this case explicitly: a phone used as a baby monitor one metre from the baby stays below the limits. In a test by Stiftung Warentest, shown by the Swiss consumer programme Kassensturz in 2020, all 20 baby monitors stayed well below the German limits, including the three apps in the test.
On top of that, with a phone you decide how much it transmits:
Wi-Fi rather than mobile data. According to the BfS, the transmit power of Wi-Fi is usually lower than that of GSM, LTE or 5G. If both phones are on the same Wi-Fi, the device next to your child does not need the mobile network.
Airplane mode, then Wi-Fi back on. On the phone next to your child, turn on airplane mode and then switch only Wi-Fi back on. The mobile radio is then off, and no call can interrupt the connection. It is not necessary: the BfS considers airplane mode unnecessary from a radiation protection point of view. It is a convenient extra precaution. How things work without Wi-Fi is explained in the article on the baby monitor app without Wi-Fi.
Sound on, picture only when needed. In Murmeli, video is off at the start. The phone next to your child transmits sounds, which take only a small fraction of the data of a video. You turn the picture on when you want to check.
One metre away, charger 50 centimetres away. The phone sits on the chest of drawers, the cable reaches the nearest socket. An old phone works well for this; what matters is covered in the article on using an old phone as a baby monitor.
A reliable connection
The first recommendation in the FOPH fact sheet is about the connection: the baby unit and the parent unit should be reliably connected. Murmeli keeps the connection open all night and raises an audible alarm if it drops. That way you always know whether the transmission is running.
As with any baby monitor, what the FOPH points out applies here too: stay close enough to be with your child quickly. A baby monitor tells you what is happening in the nursery. Supervision stays with you.
Frequently asked questions
Is baby monitor radiation harmful?
Based on current knowledge, no. In its baby monitor fact sheet from March 2026, the FOPH writes that no health risk is to be expected. Measured devices were far below the limits at one metre, and even right next to the device baby monitors comply with the limit. Distance and turning the picture on only when needed are a simple extra precaution.
Is a phone safe to use as a baby monitor?
Yes. According to the FOPH, a phone used as a baby monitor one metre from the baby also stays below the limits. It transmits least when it is connected over Wi-Fi rather than the mobile network and video only runs when needed.
How far from the baby should the baby monitor be?
The FOPH recommends at least one metre between the baby unit and the cot, and 50 centimetres for the power adapter. A chest of drawers or a shelf next to the cot is usually the right spot.
Does a phone used as a baby monitor emit more than a regular baby monitor?
Not as a rule. A DECT baby monitor may transmit at up to 250 milliwatts, a Wi-Fi device in the 2.4 GHz band at no more than 100 milliwatts. A phone on Wi-Fi is therefore rather on the lower side. According to the FOPH, both stay below the limits at one metre.
Does airplane mode help when the phone is next to the baby?
It switches off the mobile radio, whose transmit power according to the BfS is usually higher than that of Wi-Fi. If you then turn Wi-Fi back on, the baby monitor app keeps working on the same Wi-Fi and no call interrupts the connection. From a radiation protection point of view, the BfS says it is not necessary.
Does a baby monitor need VOX?
No. VOX is voice activation that makes a radio baby monitor transmit only when there is noise. The FOPH mentions it as a possible precaution. Devices that transmit continuously also stay below the limits at one metre.
Do video baby monitors emit more?
During video transmission they transmit without a break and send more data. That is why in an app like Murmeli the picture is off at the start. You hear your child all night and turn the picture on only when you want to check.