Field note · United Kingdom
Which Size Mobile Signal Booster Do I Need? 300, 500 or 1,000 m² Kits Explained (UK)
Shopping for a mobile signal booster? How to size a kit for a flat, house, office or farm in the UK, what the m² figure really means, and what to check before you buy.
Short answer
Pick a booster size by the floor area you need covered, the number of walls and floors the signal must pass through, and how strong the signal is outside. As a rough guide, a 300 m² class kit suits a flat or small house, 500 m² a larger house or small office, and 1,000 m² an office floor, shop or farmhouse with outbuildings. Weak outdoor signal shrinks real coverage, so size up if you only get one or two bars outside.
What the coverage figure on a booster really means
Every kit in our UK shop is labelled with a coverage area such as 300, 500 or 1,000 m². That figure is what the kit can cover in good conditions: a clear outdoor signal of three bars or more, an open-plan layout and the indoor antenna in a central spot. It is a ceiling, not a promise.
In real homes the number drops. Every wall, floor and fire door the signal has to pass through costs coverage, and so does a weak signal outside. A 500 m² kit installed where the outside signal is one bar may only fill a few rooms well. That is why the most useful question is not just how big your building is, but how much signal you have to work with.
Step 1: measure the signal outside
Before choosing a size, find out what EE, Vodafone, O2 or Three signal you actually get outside. Turn Wi-Fi off, stand where an outdoor antenna could go (a gable wall, chimney or roof edge) and make a test call. On Android you can read the signal strength in dBm in the phone's status settings; on iPhone, a speed test and a call are a good practical check.
As a rule of thumb: three bars or more outside means a kit will usually reach its rated area; two bars means plan for about half to two-thirds of it; one bar or less means you need the next size up, a higher-gain outdoor antenna, or a better antenna position. If there is no usable signal anywhere outside, no booster can help, and Wi-Fi calling or a carrier solution is the answer.
Step 2: match the kit to your building
A 300 m² class kit suits most flats, terraced houses and small semis, especially where the problem is one or two dead rooms. A 500 m² class kit suits detached houses, homes with a loft conversion or basement, and small offices or shops. A 1,000 m² class kit is for an open office floor, a warehouse corner, a pub or restaurant, or a farmhouse where you also want signal in the yard or a nearby barn.
Count floors as well as area. Signal travels sideways more easily than through a concrete floor, so a three-storey house often needs a second indoor antenna even if the total area looks small. Stone cottages, new-builds with foil-backed insulation and buildings with coated glass also benefit from sizing up one step.
Step 3: choose the right bands
Size is only half the choice. The kit must boost the frequencies your network uses at your address. Our Universal kits cover 700, 800, 900, 1800, 2100 and 2600 MHz, the main 4G and 3G bands used by UK networks, while the 4G-only and 5G kits are for people who know which band they need. If your household uses more than one network, choose a multi-band kit so everyone benefits.
If you are unsure, Ofcom's mobile coverage checker shows which networks and technologies reach your postcode, and our advisor can match a kit to your network and building from a few details.
Step 4: plan the installation
A typical install has three parts: an outdoor antenna mounted high and pointed towards the nearest mast, a cable into the building, and the booster with one or more indoor antennas. Keep the outdoor and indoor antennas well apart, ideally with a wall or roof between them, so the booster does not feed back on itself. Longer cable runs lose some signal, so place the booster as close to the outdoor antenna as practical.
In the UK, static mobile repeaters can be used without a licence only if they meet Ofcom's technical requirements (IR 2102). Ofcom publishes guidance and a list of repeaters that meet those rules, so check the exact model before installing. We don't claim any product is Ofcom-approved; please check for yourself, and ask us if you need the model details.
Quick sizing examples
A two-bed flat with one weak bedroom and two bars outside: 300 m² class kit. A four-bed detached house with thick walls and one bar upstairs outside: 500 m² class kit with the antenna on the gable end. A 600 m² open-plan office with three bars on the roof: 1,000 m² class kit. A farmhouse plus an adjoining workshop: 1,000 m² class kit, or talk to us about an extra indoor antenna.
Frequently asked questions
Is a bigger mobile signal booster always better?
Not always. A bigger kit costs more and needs careful installation to avoid feedback. Choose the size that matches your floor area, layout and outside signal, and size up one step only for weak outside signal or difficult walls.
Can one booster cover two floors?
Often yes, with a second indoor antenna or by placing the indoor antenna on the stairwell. Concrete floors block signal strongly, so plan antennas per floor in larger homes.
Will a booster work if I have no signal outside?
No. A booster can only amplify signal that already reaches the outdoor antenna. If there is nothing usable outside, use Wi-Fi calling or contact your network.
Do boosters work for all UK networks?
Multi-band kits such as our Universal range cover the main bands used by EE, Vodafone, O2 and Three, so one kit can help everyone in the building. Check the product page for the exact bands.
Are mobile signal boosters legal in the UK?
Static repeaters may be used licence-exempt only if they meet Ofcom's IR 2102 requirements. Check the exact model against Ofcom's guidance before installing.