Cell Phone Signal Booster Coverage Claims

You’re shopping for a cellular signal booster.

One says it covers 300 m².

Another says 1,000 m².

Then you find one claiming 5,000 m².

Fantastic. Bigger number wins. Add to cart.

Except... not quite.

When it comes to cellular signal boosters, square metres have become a surprisingly stretchy unit of measurement.

And because we spend an arguably unhealthy amount of time thinking about signal at Bolton, we decided to dig into it.

We reviewed 86 South African competitor product pages and listings, comparing the advertised coverage against the specifications that actually drive RF performance: amplifier gain and output power.

What we found was interesting.

Very interesting.

We Went Looking for the Physics Behind the Square Metres

Here’s a taste of what turned up in our benchmark:

 

Same published amplifier numbers.

Very different square metres.

On one competitor website currently, for example, a booster advertised for 300 m² and another advertised for 600 m² both publish 68–72 dB maximum gain and 22 dBm output power.

That doesn't automatically mean either coverage figure is wrong.

It means something much more important:

Coverage cannot be determined from one headline number.

In fact, when we analysed the mainstream products in our benchmark, published output power had almost no relationship to the coverage figures being advertised.

So, no, there isn't a secret RF formula that goes:

22 dBm + 72 dB = exactly 600 m².

Physics would like a few more details, please.

First Things First: A Booster Doesn't Create Signal

This is probably the most important thing to understand about any cellular signal booster.

It takes the signal that already exists outside your building, captures it with an outdoor antenna, amplifies it, and redistributes it indoors.

That's it.

No tower in a box. No cellular magic wand.

Bolton's signal booster guide describes the same three-part process: outdoor antenna, amplifier, indoor antenna.

And that means the strength of the signal entering the system has a massive influence on what can come out the other side.

Imagine two identical houses with exactly the same booster.

House A has a strong -70 dBm signal on the roof.

House B has a weak -107 dBm signal.

Same booster.

Same box.

Same impressive-looking specification sheet.

Very different result.

This is exactly why Bolton doesn't simply slap one giant square-metre number onto a booster and call it a day.

Coverage Is an Outcome, Not a Specification

Here's the simplest way we can put it:

Outdoor signal + amplifier capability + antenna system − RF losses = the indoor signal you actually get.

And there are quite a few things hiding inside that little equation.

Your outside signal matters.

The frequency matters.

Your amplifier gain matters.

Its maximum downlink and uplink output power matter.

Your outdoor antenna matters.

Your indoor antenna matters.

Cable length matters.

Splitters matter.

Concrete walls matter.

Steel matters.

Low-E glass definitely has opinions on the subject.

Even where you physically put the indoor antenna changes the result.

This is why a credible coverage estimate should describe the conditions under which that coverage is achievable.

Not just the biggest number that fits nicely next to a shopping-cart button.

Gain: The Number Everyone Likes to Quote

Gain tells us how much the amplifier can increase the strength of the signal it receives.

It's measured in dB.

Here's where things get slightly geeky, but stick with us.

Decibels are logarithmic.

A 3 dB increase represents roughly double the power.

A 10 dB increase represents ten times the power.

A 20 dB increase represents one hundred times the power.

So a few dB can be a much bigger difference than the numbers make it look. Bolton makes the same point in its booster guide: +3 dB is a significant increase because dB works logarithmically.

But here's the bit marketers sometimes conveniently forget:

Twice the power does not automatically mean twice the square metres.

Buildings aren't empty laboratory chambers.

Signal hits walls. It travels through ceilings. It loses energy through cable. It gets divided between antennas. Different cellular frequencies behave differently through the same structure.

Gain is important.

It just isn't a floor plan.

Then There's Downlink Power — and This One Really Matters

If gain tells you how much a weak signal can be amplified, downlink output power helps tell you how much amplified signal the system can actually distribute indoors.

It's measured in dBm.

And because dBm is logarithmic too, these numbers can be deceptive if you're just looking at them side by side.

Consider this:

10 dBm = 10 milliwatts

20 dBm = 100 milliwatts

25 dBm ≈ 316 milliwatts

So the difference between 10 dBm and 25 dBm isn't 2.5 times the power.

It's roughly 31.6 times the power.

Now things get interesting.

Our current WilsonPro A1000 publishes up to +25 dBm maximum downlink output power, +30 dBm uplink power, and 85 dB maximum gain. Under excellent outdoor signal conditions and with a suitably designed antenna system, we currently estimate coverage of up to 1,500 m².

Our competitor benchmark, meanwhile, found products publishing 10 dBm downlink power and 65 dB gain alongside coverage claims reaching several thousand square metres.

Does that prove those systems cannot cover those areas?

No.

And we're not going to pretend it does.

But if a significantly lower-powered amplifier claims significantly more coverage, there is a perfectly reasonable question to ask:

Under what conditions?

That little question does a lot of work.

Don't Forget Uplink: Your Phone Has to Talk Back

Cellular communication is a two-way conversation.

The downlink is the tower talking to your phone.

The uplink is your phone talking back to the tower.

You need both.

A system that gives your phone plenty of signal indoors but doesn't have enough uplink capability to communicate effectively back to a distant tower can still leave you with a poor experience.

Think of it like standing across a football field.

It's brilliant if you can hear the other person shouting.

Less brilliant if they can't hear you.

That's why we want customers comparing gain, downlink power and uplink power, rather than treating a coverage number as the entire specification.

The current A1000, for example, publishes all three: 85 dB maximum gain, +25 dBm maximum downlink and +30 dBm maximum uplink.

If you're comparing boosters and those numbers are nowhere to be found, we'd be asking why.

Your Outside Signal Changes Everything

This is where Bolton's coverage tables differ from the typical "UP TO ELEVENTY-BILLION SQUARE METRES!" approach.

Take the WilsonPro A500.

With excellent outside signal of roughly -55 to -70 dBm, we currently estimate indoor coverage of up to 750 m².

Move down to -86 to -95 dBm, and our estimate falls to around 500 m².

At -106 to -110 dBm, we're talking about approximately 150 m².

Same A500.

Same 70 dB maximum gain.

Same +20 dBm maximum downlink output.

The thing that changed was the signal going into it.

The A1000 follows the same principle. With excellent outdoor signal, our current estimate reaches up to 1,500 m². At -96 to -105 dBm, that drops to around 650 m². With very weak outdoor signal below -110 dBm, we'd rather recommend a site assessment than invent a reassuring number.

That's not us being conservative for fun.

That's RF.

Then Your Building Gets a Vote

Here's another reason coverage claims need context.

A 1,000 m² open-plan warehouse and a 1,000 m² reinforced-concrete building are not the same RF environment.

Not even close.

Cellular signal loses energy as it passes through building materials. Concrete, metal structures, coated glass and other materials can significantly attenuate cellular frequencies; even ordinary interior materials introduce some loss.

An indoor dome antenna broadcasting into a large open-plan area may perform very differently from that same antenna trying to punch through several concrete walls.

Add another indoor antenna and you can improve distribution — but now you may also need a splitter.

A splitter introduces loss.

Longer coax introduces loss.

Every part of the system affects the final RF link budget.

That's why professional commercial systems aren't designed by asking only:

"How many square metres is the building?"

If only our jobs were that easy.

So What Does “Up to 5,000 m²” Actually Mean?

Potentially?

It means the system may achieve that coverage under the conditions assumed by whoever published the figure.

And that's the important part.

Was the incoming outdoor signal -60 dBm or -105 dBm?

Was the area completely open?

How many indoor antennas were used?

What building materials were involved?

Which frequency was being tested?

How much cable was installed?

Were there splitters or couplers?

What target signal level counted as "covered"?

Was the number calculated, laboratory tested or field tested?

Was it one amplifier or a larger multi-stage system?

Without that information, an "up to" coverage figure is not useless.

But it is incomplete.

And when you're spending real money trying to solve a real connectivity problem, incomplete isn't quite good enough.

The Bolton Standard: We'd Rather Give You the Useful Number

Could we put enormous theoretical coverage figures all over our website?

Sure.

We know where the Caps Lock key is.

But we'd rather help you choose the right system.

That's why you'll increasingly see Bolton publish coverage against measured outdoor signal strength, along with the amplifier's actual technical specifications.

For example, our current range positions the WilsonPro A500 at up to 750 m² under excellent signal conditions, with up to 70 dB gain, +30 dBm uplink and +20 dBm downlink. The WilsonPro A1000 steps up to 85 dB maximum gain, +30 dBm uplink and +25 dBm downlink, with coverage up to 1,500 m² under excellent outdoor conditions and a correctly designed distribution system.

Notice all those words after the square metres?

They're important.

Because realistic performance claims are part of The Bolton Standard.

We don't want you buying the booster with the biggest number.

We want you buying the booster that's right for your signal.

Before You Compare Square Metres, Ask These Questions

1. What is the maximum amplifier gain? A few dB can represent a very significant difference in amplification capability.
2. What are the uplink and downlink output powers? If they're not published separately, ask for them.
3. What outside signal strength was assumed for the advertised coverage? Ideally, look for a measured dBm value rather than simply "bars".
4. What installation was used to achieve the coverage figure? One indoor antenna? Four? Open-plan building? Reinforced concrete? These details matter.
5. Can the supplier explain how the coverage figure was determined? If the technical answer is just "it covers 5,000 m²", you haven't actually received a technical answer.

Big Claims Are Easy. Good RF Takes a Little More Work.

We're not suggesting you should ignore coverage figures.

We publish them too.

They're useful.

What we're saying is that square metres should be the beginning of the conversation, not the end of it.

Because a signal booster doesn't know how big the number on its product page is.

It knows the signal arriving at its antenna.

It knows its gain.

It knows how much output power it can produce.

And then it has to deal with your cables, walls, antennas, frequencies and layout.

Physics can be annoyingly immune to marketing.

Fortunately, we quite like physics.

Not sure what your building actually needs? Measure your outdoor signal in dBm and talk to the Bolton team. We'll help you work from the signal you really have — not the square metres someone would really like you to believe.

Bolton Technical. Built for Better Signal.