Broadband speed guarantees: Are they completely meaningless?
Dan Howdle • November 27th, 2025
Broadband speed guarantees sound great on paper – a simple promise that your connection will stay above a certain, comfy threshold. But if you’ve ever dug into the small print (and we're willing to bet you haven't – that's our job), you’ll see they’re not quite as solid a backstop as providers like to make out.
The question is: Do speed guarantees offer any meaningful protection, or are they in actual fact rather flimsy? They're kind of both, but that requires and explanation. So let's look at what’s actually being guaranteed, how providers measure it, and what you can realistically expect if your speeds fall short of your expectations.
What are speed guarantees and who offers them?
Speed guarantees are a promise by your provider that your broadband speed will never fall below a certain threshold – a certain number of megabits per second, dependent on how fast your broadband's supposed to be. Speed guarantees and Wi-Fi guarantees are two completely different things too, so be mindful of that. We'll cover that a bit further down.
The reality is quite murky, in fact. One issue is that each provider defines, measures and enforces its speed guarantee differently. Added to that, the number you see in your speed test isn’t usually the number providers will accept to prove they're not making good on their promises.
That's because the speed you might be getting on an iPhone connected to your router over Wi-Fi, for example, may be very different to the speed your provider measures actually coming into your home, whether that's because your iPhone is old and slow, or because you simply can't push 900Mbps over a Wi-Fi signal outside of a lab.
Here’s a quick look at how a couple of major providers stack up when it comes to the minimum guaranteed speeds they publish for their Full Fibre packages. Really this is just to illustrate the sort of guarantee you can expect.
| Provider | Packages | Minimum guaranteed line speed | Compensation |
|---|---|---|---|
| BT | Full Fibre 100 / 300 / 500 / 900 | 100 Mbps / 150 Mbps / 250 Mbps / 700 Mbps | £20 pre-paid card, option to cancel |
| Sky | Any Sky Full-Fibre package | Will be quoted when you sign up | One month’s broadband bill, or exit without fees |
To reiterate: Guaranteed speeds are based on the performance of the line coming into your home, tested directly at the router, and often using only your provider's in-house speed test. They don’t reflect Wi-Fi performance, the position of your devices, or how many people are using the connection at once. Calling up your provider with a 'slow Wi-Fi' issue won't cut it. That's simply not what's being 'guaranteed'.
Also, providers typically only consider it claimable if your line repeatedly falls below the guaranteed speed over several days.
Case in point: BT's Speed Guarantee
We're not singling out BT here. Rather, here's a straightforward example of how a typical speed guarantee actually works in the real world.
- Personalised minimum speed – BT gives you an individual guaranteed speed when you sign up or renew
- £20 compensation – If your line stays below that speed and BT can’t fix it within 30 days, you get £20 on a prepaid card
- Line speed only – The guarantee applies to the speed reaching your BT Hub, not your Wi-Fi performance around the home
- Tests required – You must run BT’s official speed test and complete their fault checks before they’ll assess the guarantee
- Leave penalty-free – If BT still can’t meet the guaranteed speed, you can cancel without early-exit fees
Still feel reassured? Because although BT (like other providers – as we say, not singling out here) likes to shout about its speed guarantee, what sort of guarantee is '£20 if you jump through all our hoops, and if we can't fix it then, well, off you trot'.
We're not certain that really fits the description of a guarantee at all, in fact. Far preferable would be 'we will fix the issue no matter the cost, and in the meantime we'll compensate you daily'. But the reality is that speed guarantees, from any provider, are nothing like that, and must be taken with a pinch of salt.
Compensation and why it doesn't really change anything
Most providers offer compensation or let you walk away penalty-free if your speeds continue to fall short and they can't fix the issue, but the amounts involved are usually quite small. In many cases, you’ll get a modest bill credit or the option to cancel your contract entirely. That often sounds more dramatic than it is – switching providers takes time, and the compensation rarely makes up for weeks of unusable broadband.
Which is why for most people who've had to lean on one of these guarantees, they often feel hollow. They exist, and they can occasionally help, but they don’t prevent everyday slowdowns or guarantee consistently fast Wi-Fi around your home. They’re a backstop, not a performance promise.
Easily compare the best deals, providers and speeds where you live. It's free and takes less than a minute to check your postcode.
Speed guarantees versus Wi-Fi guarantees – two completely different things
One of the biggest misunderstandings around provider guarantees is that a speed guarantee covers your whole home. It doesn’t. A speed guarantee only applies to the speed delivered to your router over the line coming into your property. A Wi-Fi guarantee, on the other hand, is about wireless coverage inside your home – an entirely separate issue with its own set of terms.
It’s easy to see why people mix the two up. Both use the word ‘guarantee’, both involve performance, and both are mooted by providers in their advertising. But if your Wi-Fi is patchy in the bedroom or your laptop struggles at the far end of the house, that has nothing to do with your minimum guaranteed speed. The line can be performing perfectly while your Wi-Fi experience feels painfully slow.
It's very easy to confuse the two
Most devices connect to your broadband via Wi-Fi. So when a provider talks about guaranteed speeds, it’s natural to assume they’re guaranteeing the experience you get on your phone or laptop. The problem is that Wi-Fi is influenced by walls, interference, old devices, microwaves, baby monitors, Christmas tree lights (yes, really!) distance from the router, and half a dozen other things your provider can’t control.
Remember: The guarantee applies only to the cable feeding your router, not the airwaves doing the last few metres.
Full Fibre 900
First month payable upfront
910Mb
Average speed
No phone line
24
Month contract
Zero upfront cost
£31.99 Per month
Effective monthly cost is calculated by adding up all the monthly costs, price rises and any discounts and dividing it by the contract length.
Once activated you'll receive claim information by email and must claim within 2 months, then activate within 3 months of it being issued.
Full Fibre Gigafast
600Mbps speed guarantee£5 fee refunded to first bill
900Mb
Average speed
Pay as you go calls
24
Month contract
Zero upfront cost
£37.00 Per month
Effective monthly cost is calculated by adding up all the monthly costs, price rises and any discounts and dividing it by the contract length.
You will be sent instructions on how to choose your Gift Card up to 120 days after your purchase. You will have 90 days to claim your Gift Card by sending it to your email or mobile phone.
Gig1 Fibre Broadband
Fixed price until March 2026 bill
1.1Gb
Average speed
No phone line
24
Month contract
Zero upfront cost
£24.99 Per month
Effective monthly cost is calculated by adding up all the monthly costs, price rises and any discounts and dividing it by the contract length.
When a speed guarantee actually helps
For all their limitations, speed guarantees aren’t completely without merit. They can be genuinely useful when something is wrong with the physical line coming into your home. If your connection is consistently underperforming, but perhaps less for the compensation your provider promises, and more for the right to leave offered if they can't fix it.
They’re also valuable in the early days after a new installation. If the line is struggling to reach the promised minimum, your provider is obliged to investigate. You can make fairly good use of the leverage a speed guarantee offers you if you experience…
- Consistently slow line performance – When your wired speeds repeatedly fall below the guaranteed minimum
- Faults on the physical line – Inconsistent speed and dropout problems that require engineering work rather than simple router resets
- A new installation struggling to stabilise – When your brand-new service can’t reach the promised speed from day one
- Local network issues – When congestion or local faults frequently push your speed below the guaranteed threshold
- Lines that simply cannot hit the minimum – When the technology in your area isn’t capable of delivering the speed you were promised
When you can leave penalty-free
Every provider’s rules differ slightly, but the principle is the same: if your connection repeatedly tests below the guaranteed speed over several days and the provider can’t fix the issue, you are entitled to leave without early-exit fees.
The process is rarely quick – you’ll need to run tests, restart equipment and allow the line to be monitored – but if the numbers remain below the guaranteed minimum and there’s no viable fix, you can walk away without penalty. Just bear in mind that your provider not being able to fix the problem at all is really quite rare.
The bottom line
Speed guarantees aren’t completely meaningless, but they’re nowhere near as reassuring as they sound to the average ear. They apply only to the line coming into your home, not the Wi-Fi you actually use, and providers only act when speeds fall below the guaranteed minimum repeatedly over several days. For most of us, that means the guarantee won’t help with everyday slowdowns and Wi-Fi frustrations.
That said, speed guarantees do have a purpose. If your line is genuinely underperforming, especially after a new installation, they give you a formal route to push for a fix and, if the provider can’t resolve the issue, the right to leave without penalty. And that's where the value is in reality – not from your provider bunging you a £20 John Lewis card to say sorry.
What they really are is a backstop, and they are definitely not a promise of perfect performance. Our advice is to take them for what they are, lean on them when you need to, and choose your broadband deal based on the the things that really matter to you.
Our expert advisors have access to special offers and can create a personalised package just for you. Give us a call!
Call 0330 221 9424
