What does an advertised 300-metre baby monitor range mean indoors in the UK?

What do box figures of 50 m and 300 m actually mean?

They are the maker's maximum distance in a stated test, not a prediction for a terrace hall. Always pair the number with the words next to it: indoor versus outdoor, and 'ideal conditions' or 'line of sight'.

These are manufacturer test figures. MayTally does not invent a 'typical UK indoor range' in metres. The usable number in your house is the walk-test, not a fraction of 300.

Why do indoor UK rooms fall so far short of the outdoor number?

Outdoor metres assume you and the camera can still see each other across open ground. Indoor metres already assume walls exist, but BT still says the published indoor figure needs a clear line of sight and that wall material, thickness, dampness, the number of walls, and metal or electrical kit nearby cut it. A mid-terrace kitchen path is short in metres and heavy in brick. That is why 12 metres of house can fail a 50-metre indoor claim.

Angelcare's UK interference note adds metal (including some window frames), microwaves, routers and phones — the things that sit on a UK kitchen path even when the tape measure looks kind.

How does Which? test range, if not by the box number?

Which? does not score monitors by reprinting 300 m. Testers walk away through three rooms, noting when picture and sound deteriorate and when the link is lost, then take the parent unit outdoors until reception declines. That method is closer to a house than a field, and it is still not a party-wall terrace or a loft-to-garden map. Use it as a reminder to walk, not as a substitute for your stairs.

How should I read a manufacturer's range line?

1. 1
   Find both numbers Look for an indoor metre figure and an outdoor metre figure on the same box or PDF. If only one number appears, treat it as incomplete until you find the manual.
2. 2
   Read the caveat Copy the words 'line of sight', 'ideal conditions' or 'walls and doors reduce range' into your notes. Those words are the meaning of the number.
3. 3
   Ignore a single huge outdoor figure A 300-metre outdoor line without the 50-metre indoor line is the field test. It does not describe a kitchen.
4. 4
   Walk your path Camera in the bedroom, parent unit along the real route. The pass mark is usable picture or sound at your stops, not 'we got close to 50 m'.

What should I not do with the number on the box?

• Do not divide 300 by the number of walls to invent a remaining range. No official page publishes that conversion.
• Do not treat 50 m indoor as a terrace floorplan. It is BT's indoor test maximum.
• Do not mix brands. A 300-metre Motorola line and a 250-metre BT line are two manuals, not one league table.
• Do not skip the beep check. BT's 1000 guide lists out-of-range and battery-low warnings as separate features — the beep is the live measurement.

Does a long advertised range change safer-sleep rules?

No. The Lullaby Trust says there is no research showing monitors help prevent SIDS, and that a monitor never replaces a parent in the room for the first six months. A 300-metre outdoor line does not stretch that rule down the garden.

In shortIn short: outdoor metres are a line-of-sight field test; indoor metres are still a best-case. Quote the model's own pair. Believe the walk, not a fraction of 300.