Short answer: there are three ways, and it is worth using two of them. Rank the transmitters from your location, which is what Aerial Aligner does from a postcode or GPS. Read the UHF channel numbers off your TV’s tuning menu and match them to a site, which tells you what the aerial is pointed at now. And look at the neighbours’ aerials, which tells you what the street settled on, right or wrong.

The reason to use more than one is that the nearest transmitter, the one you are currently on, and the one you should be on are three different questions with, quite often, three different answers.

Method 1: rank from your location

Ofcom publishes the position, power, polarisation and channels of every UK terrestrial TV transmitter. Aerial Aligner carries that dataset, 1,130 sites, and from your postcode or GPS position it ranks them by predicted signal. Distance is shown, but it is not the sort order, because power varies from a few watts at a valley relay to 200 kW at the biggest main stations. A 50 kW site 30 km away routinely outranks a 7 W relay 10 km away, and the main station carries more multiplexes.

The ranked list gives you a first choice and a second choice, with the bearing to each. Our guide on which way an aerial should point explains the ranking and works through an example.

The postcode lookup is the only thing the app sends anywhere; it converts a postcode to a grid reference. The ranking itself runs on the phone, offline.

Method 2: read your TV’s tuning information

Every Freeview television and box has a signal or tuning information screen, usually under Settings, Channels or Installation, and it shows the UHF channel number, sometimes called the RF channel or frequency, that each service is being received on. Write down two or three of them.

Then match them against the channels each transmitter uses. Aerial Aligner lists them for every site. If your TV says it is receiving BBC One on channel 23 and ITV on channel 26, and Crystal Palace uses 23 and 26 while your nearest relay uses 41 and 44, you are on Crystal Palace, whatever the aerial looks like.

This method tells you what the aerial is actually pointed at, which matters when you have moved into a house, inherited an aerial and have no idea what the previous occupant set up.

For reference, the UK’s largest main stations and their current channels from Ofcom’s data:

Transmitter Region Power Polarisation UHF channels Multiplexes
Crystal Palace London 200 kW H 22, 23, 25, 26, 28, 30, 35 7
Sutton Coldfield Midlands 200 kW H 36, 39, 40, 42, 43, 45, 46, 48 8
Rowridge South 200 kW H and V 21, 22, 24, 25, 27, 28, 37 7
Sandy Heath East 180 kW H 21, 24, 27, 33, 36, 48 6
Emley Moor North 174 kW H 33, 36, 39, 41, 44, 47, 48 7
Belmont North 150 kW H 22, 23, 25, 26, 28, 30, 32 7
Winter Hill North West 100 kW H 21, 24, 27, 29, 31, 32, 34, 35, 37, 40 10
Black Hill Scotland 100 kW H 30, 40, 41, 43, 44, 46, 47 7
Divis Northern Ireland 100 kW H 21, 23, 24, 26, 27, 30, 36, 48 8
Wenvoe Wales 100 kW H 31, 37, 39, 41, 42, 44, 45, 47 8
Mendip West 100 kW H 30, 32, 33, 34, 35, 36, 48 7
Bilsdale North East and Cumbria 100 kW H 21, 24, 27, 40, 43, 46 6
Pontop Pike North East and Cumbria 100 kW H 30, 32, 33, 34, 35, 39, 42, 45 8
Caradon Hill South West 100 kW H 21, 22, 24, 25, 27, 28 6
Tacolneston East 100 kW H 32, 39, 40, 42, 43, 45, 46 7
Oxford South 100 kW H 22, 29, 31, 37, 41, 44, 46, 47 8
Durris Scotland 100 kW H 22, 23, 25, 26, 28, 30, 41 7
Caldbeck North East and Cumbria 100 kW H 22, 23, 25, 26, 28, 29, 30, 33 8
Sudbury East 100 kW H 29, 31, 37, 41, 44, 47 6
Dover South East 80 kW H 33, 35, 36, 39, 42, 48 6
Hannington South 50 kW H 32, 34, 39, 40, 42, 43, 45, 46 8
Waltham East Midlands 50 kW H 29, 31, 32, 34, 35, 37, 41 7

Channel numbers change at retunes; these are as published by Ofcom and bundled in Aerial Aligner at the time of writing. Every UK Freeview transmitter currently uses channels between 21 and 48.

Method 3: look at the neighbours

A street’s aerials usually agree with each other, and they carry two pieces of information: the direction they point and whether the rods are horizontal or vertical. Horizontal rods mean a horizontally polarised transmitter, which is almost always a main station. Vertical rods mean a relay.

It is a sanity check, not an answer. Streets get it wrong in a consistent way: an installer years ago pointed everyone at the local relay because it was easy, the relay carries three multiplexes, and every house has been missing the same channels ever since. If the neighbours are on a vertical relay and the ranked list shows a main station with a clear path, the main station is worth trying.

Putting the three together

  1. Rank from your location to see the candidates and their bearings.
  2. Read the tuning menu to see what you are on now.
  3. Check the neighbours for direction and polarisation.

If all three agree, you are done. If the tuning menu says you are on a relay and the ranking prefers a main station, the missing channels are probably the multiplexes the relay does not carry, and a repoint (with the rods turned to match) is the fix. If the ranking’s first choice is blocked by a hill or a building you can see, its second choice with a clear line is the better bet, and that is what the ranked list is for.

The official checker

Freeview’s own website has a coverage checker that predicts which transmitter and which channels a given postcode should receive. It is the reference for what an address is expected to get. Aerial Aligner is the tool for standing on the roof or at the caravan pitch and pointing at it.

Sources

Transmitter positions, powers, polarisations, channels and multiplexes are from Ofcom’s published transmitter parameters, as bundled in Aerial Aligner and refreshed from that source. The predicted-signal ranking is the app’s own calibrated estimate, not an Ofcom coverage prediction.

The table and dataset facts were extracted on 11 September 2026 from the Ofcom transmitter data bundled in Aerial Aligner 2.0. Plan CD is not affiliated with Ofcom, Freeview or any broadcaster.