How can I test baby monitor range before baby sleeps upstairs?

Why does the box say 300 metres when the signal drops on the landing?

The headline range on a baby monitor box is an open-field figure: two units, line of sight, nothing in between. VTech's UK spec sheets are unusually honest about this and print two numbers — 50 m indoor / 300 m outdoor for the VM819, VM818HD and VM919HD. Motorola Nursery quotes "up to 1,000 ft (300 m)" on its PIP1610 HD and PIP1500 pages and does not publish an indoor figure; its user guides simply say the range "will be affected by environmental conditions".

So a realistic indoor working distance is roughly a sixth to a third of the number on the box, and in a British house with solid walls and a Wi-Fi router in the hall it can be less. Twenty metres through two floors is a normal result, not a faulty unit. The only range figure that matters is the one you measure yourself, with everything switched on.

VTech's own quick-start guide tells you to "test the sound reception every time you turn on the units or move one of the components". That is the manufacturer's instruction, not an optional extra.

How do I test monitor range before the first night upstairs?

This takes about ten minutes and you only need a phone. Do it in the evening, when the router, television, microwave and any cordless phone are all in use, because that is the environment the monitor has to survive.

1. 1
   Charge the parent unit fully first A low battery makes some parent units drop the video link earlier. Use the supplied adapter and give it the full first charge the guide asks for (12 hours for the VTech VM819, 16 hours for the Motorola VM50G).
2. 2
   Place the camera where it will actually live At least 1 m from the cot and its cables out of reach, and at least 1 m (VTech) to 1.5 m (Motorola) from a Wi-Fi router, microwave or Bluetooth speaker. Do not test from a temporary spot on the bed — the position you test is the position you keep.
3. 3
   Give the camera something steady to hear Set a phone alarm, a ticking clock or a white-noise track playing quietly at cot level. You need continuous sound so you can tell a silent room from a dropped link.
4. 4
   Walk your real evening route Take the parent unit downstairs the way you will tonight: kitchen, sofa, bathroom, back door, garden if you use it. At each stop, wait 15 seconds and note three things — picture, sound and the signal-bar icon.
5. 5
   Stress the worst spots Stand by the microwave while it runs. Stand next to the router. Close the kitchen door. If you have a DECT cordless phone, make a call from its base. Note where the bars drop.
6. 6
   Walk out of range on purpose Keep going until the unit alarms. You need to hear what the no-link alert sounds like (VTech calls it "No Link to Camera"; Motorola "Out of range") and how many seconds it takes. If your monitor never alarms and just freezes the picture, you now know to watch the bars rather than trust the screen.
7. 7
   Test the overnight position last Put the parent unit where it will sit at night — bedside, on charge — and check it holds a full-bar link for a few minutes. Then repeat the whole walk any time you move the camera, the router or the parent unit's charging spot.

Write the results on a sticky note on the parent unit — "kitchen 3 bars, garden 1 bar, no link past the shed" — for whoever babysits.

What blocks a baby monitor signal in a UK house?

Video monitors and most digital audio monitors use short-range radio at 1.9 GHz (DECT) or 2.4 GHz (FHSS and Wi-Fi). At those frequencies dense, wet or metallic materials absorb or reflect the signal. Both Motorola's and Hubble's guides name the same culprits: large metal objects, mirrors, reinforced concrete, other solid walls, and other 2.4 GHz kit. British housing adds a few of its own.

Why does my video baby monitor lose signal upstairs when an audio one was fine?

Video needs far more data per second than audio, so a video link fails earlier as the signal weakens. Where an audio monitor degrades gracefully — hiss, then silence — a video parent unit freezes, pixelates or drops to "searching" while there is still enough signal for sound. Three other things are usually behind a monitor that "worked downstairs last week":

• Something moved. A new mesh Wi-Fi node, a smart speaker, or the router being shifted to a different shelf can push a marginal link over the edge. Re-run the test after any change in the house.
• Orientation. Parent-unit aerials are directional. Hubble's advice to rotate the unit 90 degrees, or move it 30 cm along the sofa arm, fixes a surprising number of dead spots.
• Battery. A worn parent-unit battery can cause the unit to drop the link, restart or lose the picture near the end of the night; see why a monitor battery drains before morning.

How can I set up an audio monitor in a terraced house?

Terraces are long and thin, so the distance from nursery to kitchen is often greater than the distance to the neighbour's router. Two things matter more than range: which wall you put the camera near and what the neighbours are running.

1. Put the baby unit on the wall furthest from the party wall, so the path to your own downstairs rooms is through your own doorways rather than through solid brick shared with next door.
2. Keep the baby unit at least 1 m from your own router and from any smart speaker in the nursery — VTech's figure for its audio and video units.
3. For a DECT audio monitor, keep the parent unit off the same shelf as a DECT cordless phone base; both hop channels, but they share the band.
4. Run the range test at 8 p.m. In a terrace the 2.4 GHz band is busiest when every household is streaming.
5. If the link is marginal at the back of the kitchen, move the parent unit rather than the baby unit; the baby unit's position is a safety decision, the parent unit's is not.

Audio monitors tolerate all of this better than video, which is why a DECT audio unit is often the first thing that actually works in a narrow Victorian terrace.

Which type of monitor works best in a two-storey Victorian house?

No brand will fix a solid-brick house, but the radio type changes what "losing signal" looks like and what you can do about it.

In shortRange is measured, not bought. Test your own house at 8 p.m. with the router and microwave on, walk out of range on purpose so you know the alert, and repeat after anything moves. In a solid-walled Victorian or terraced house, an audio DECT unit holds a link longest, an FHSS video unit is the honest middle ground, and a Wi-Fi model only works where your Wi-Fi already does.

Does a longer-range monitor change where my baby should sleep?

No. The NHS and the Lullaby Trust both advise that the safest place for a baby to sleep for the first six months is in a cot, on their back, in the same room as you, day and night. The Lullaby Trust adds that there is no research showing monitors help prevent sudden infant death syndrome and that a monitor "can never replace a parent or carer's supervision". A monitor that reaches the garden is convenient; it is not a reason to move a young baby upstairs alone earlier than you otherwise would.

If you are buying second-hand to get a longer-range model, search the model code first — see how to check a used baby monitor for recalls — and remember that not found ≠ safe.