By giffgaff is offering a £15 unlimited data SIM card in August 2025. It’s an 18-month contract with a fixed monthly price and 5G coverage from O2.
In the UK, giffgaff is currently offering their unlimited data SIM for a reduced price of just £15 per month. This special deal is available on an 18-month contract and comes with a fixed monthly price for the whole of that time (no annual price rises). You’ll get 4G & 5G coverage from the O2 network, plus inclusive EU roaming (up to 5GB per month).
Get unlimited data for £15 on giffgaff →
In this article, we’ll review giffgaff’s unlimited data offer. We’ll start by looking at what their £15 unlimited data SIM card includes, along with the fair usage policy. We’ll also look at how giffgaff’s unlimited data plan compares to other mobile networks, and how you can keep your current phone number when you move to this deal.
| Special Offer: | Unlimited data for £15 (18 months) |
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| Reasons To Buy: |
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| Reasons To Avoid: |
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| Fair Use Limits: |
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| Coverage: | O2 coverage (4G & 5G) – check postcode |
Contents
Giffgaff’s £15 Unlimited Data SIM
As a special offer that’s running until the 4th December 2025, giffgaff has discounted their unlimited data SIM to just £15 per month for 18 months. This is reduced from the normal price of £25 per month, and is available for both new and existing customers through this link.
| Network | Data | Monthly Cost | |
|---|---|---|---|
| Unlimited data | £15.00 per month 18 month contract | See deal |
There are a couple of things we really like about this £15 deal:
- You’ll get unlimited data in the UK. You can use as much data as you like, without the need to worry about getting cut off in the middle of the month. Although there’s a fair usage limit of 650GB per month, it’s only really used as a threshold for giffgaff to take a look into your usage. In addition, this only applies when you go over the 650GB threshold twice in a 6-month period. So there’s no need to worry about going over it by accident from time to time.
- You can share your data with other devices through tethering & personal hotspot. If you’d like to use the unlimited data SIM card for mobile broadband (e.g. for connecting your laptop or tablet to the internet), that’s absolutely fine. You can even share your unlimited data allowance with friends and family via hotspot. The only fair use restriction is that you shouldn’t tether to more than 12 devices at the same time on a regular basis. If so, giffgaff may take a look into your usage.
- The monthly price is fixed, with no annual price rises. The cost of your plan is fixed at £15 per month for the whole of your 18-month contract. This allows you to avoid the annual price rises, which are often seen on other networks.
Although it’s an 18-month contract, you have flexibility (including downgrading). To get this £15 unlimited data deal, you’ll need to make an 18-month commitment to staying on giffgaff. However, as their contracts are flexible, you can move to another plan in giffgaff’s 18-month range at any time. If you need to cancel entirely, the termination fee is 50% of your remaining monthly payments.- You’ll be able to use your plan at no extra cost in the EU (up to 5GB per month). There are 38 European destinations where you’re able to use your plan at no extra cost. Do note, however, that data usage is capped at 5GB per month in the EU.
There are, also, some disadvantages to this deal.
Firstly, although giffgaff’s network offers good performance and coverage in many parts of the country, there are certain areas where the download speeds are poor (e.g. in areas where the O2 network is congested, or where coverage is poor). If you’re located in one of these areas, this is a major downside to consider.
Secondly, the inclusive EU roaming offer is capped at just 5GB data per month. While that’s enough for many people (especially if you’re trying to stay off your phone when on holiday), we can’t help but feel it’s a little bit stingy on a plan where you get unlimited data in the UK.
Finally, although it’s an 18-month contract that gives you some flexibility, it still isn’t as flexible as a one-month rolling plan (where you can cancel entirely at any time). If you’re looking for complete flexibility on cancellations, giffgaff charges £35 for the equivalent plan on a monthly rolling basis. Alternatively, you can consider a unlimited data SIM from other networks like SMARTY, Talkmobile or Lebara.
Fair Use Policy
On giffgaff’s unlimited data plans (including both the 18-month contract and the 1-month rolling plan), there are two key restrictions worth being aware of, as detailed in giffgaff’s fair use policy.
- There’s a 650GB per month threshold in the Fair Usage Policy. According to giffgaff, they monitor usage of this plan for anything that might harm their network or other member’s ability to use it. As a threshold, their fair usage policy states that you should avoid “regularly using unreasonably large amounts of data, including but not limited using around 650GB of data twice within a 6-month period”. For most people, that shouldn’t be anything to worry. That’s because it’s equivalent to streaming more than 200 hours of HD video on your phone each month (that’s more than 7 hours of HD video, every single day).
- You shouldn’t tether to more than 12 devices on a regular basis. Although it’s possible to share your data with other devices (e.g. with laptops, tablets, friends and family), the fair usage policy states that you should “avoid regularly tethering to 12 or more devices”. Once again, this shouldn’t normally be a problem for most users, unless you’re using the SIM card for something like 4G home broadband.
If you have one of giffgaff’s older plans with ‘Always On’ data, there’s a speed reduction to 384kbps once you’ve used more than 80GB data per month. This speed restriction no longer applies on the latest unlimited data plans.
Alternatives
Alongside the 18-month contract, giffgaff also offers a version of this unlimited data plan on a monthly rolling basis. However, this is priced at £35 per month:
| Network | Data | Monthly Cost | |
|---|---|---|---|
| Unlimited data | £35.00 per month 1 month rolling | See deal |
In most cases, you’re better off choosing the 18-month contract due to the lower monthly price. It still gives you flexibility to change your plan as needed (e.g. downgrading to a cheaper plan within giffgaff’s 18-month range). If you’d like to cancel the service entirely before the end of the 18-month contract, you can downgrade to a cheaper plan first (e.g. to giffgaff’s £8 plan) and you would then need to pay just 50% of the remaining monthly payments for your contract length (i.e. just £4 for each month that remains on your plan). Changing plans will not reset the length of your contract.
For unlimited data on another mobile network that uses O2 coverage, you can also consider the unlimited data plans from Sky and Tesco Mobile:
| Network | Data | Monthly Cost | |
|---|---|---|---|
| Unlimited data | £20.00 per month 12 month contract | See deal |
| Unlimited data | £25.00 per month 24 month contract Monthly cost rising to £26.50 on 1 Apr 2026 | See deal |
| Unlimited data | £30.00 per month 12 month contract Monthly cost will rise each April by CPI inflation plus 3.9% | See deal |
For more information, see our full overview of the UK’s best unlimited data plans.
Network & Coverage
On giffgaff, you’ll have access to 4G and 5G coverage from the O2 network. This includes 99% population coverage on 4G, plus 5G coverage in more than 750 UK towns and cities.
To check the coverage that’s available in your area, enter your postcode on giffgaff’s online coverage map:
Check giffgaff coverage (giffgaff.com) →
Both 4G Calling and Wi-Fi Calling are available on giffgaff, providing you have a mobile phone that’s compatible with the feature.
Keeping Your Phone Number
If you’re switching from another mobile network to giffgaff, it’s a straightforward process to keep your current phone number.
Start by ordering your unlimited data SIM from giffgaff. Once you’ve done that, request a PAC Code from your current mobile network. You can get one using their website or app, or by texting PAC to 65075.
When your giffgaff SIM card arrives in the post, activate it and fill out the number transfer form on giffgaff’s website. Once you’ve done that, your phone number will normally be scheduled for the next working day.
For a step-by-step guide on transferring your phone number to giffgaff, please select your current mobile network from the drop-down menu below:
More Information
For more information about giffgaff’s £15 unlimited data SIM, please see their official website. You can also read our overview of unlimited data plans in the UK.
Philip Arthur said:
Since November 2020 till beginning of April this year l had unlimited calls for free.
Now, after adding more credit, for an overseas call, l am being charged for every local l make!
Can anyone tell me the reason for the above and how l can go back to having unlimited access to giffgaff?
Ken replied:
Hi Philip,
Thanks for your comment. Are you referring to the free giffgaff-to-giffgaff calls? I believe this requires you to top-up by £10, after which you’ll get free calls to other giffgaff customers for the next 3 months.
Ken
Philip Arthur replied:
No. I made regular calls to my doctor over the previous 5 months using my giffgaff and called them via landline (that is to say the sugery are not giffgaff subscribers).
How can l go back to my original account agreement between us. That is to say unlimitted calls and automatic top up each month of £8?
Ken replied:
Hi Philip,
Ah, ok that makes sense now. I think you previously had a giffgaff goodybag bundle on your account? You can now get a goodybag from £6/month that includes unlimited calling. If so, there should be an option to buy that inside your giffgaff account area or app.
Ken
Ebony Patterson said:
I bought this plan before realising that my router arrived with a Smarty SIM already. I have good signal strength, the router is in the best spot in the flat and there are no reported network/coverage issues with O2 in the area. I have only just started using the pan and only get maximum 2-3 mbps upload and 0.5-1.5 download. When the plan runs out I will try Smarty for comparison.
Demi said:
I have 1 one day left on my giffgaff always on data will it run out at midnight or the time I purchased it a month ago?
Ken replied:
Hi Demi,
Thanks for your comment. I believe all of giffgaff’s bundles run until midnight.
Ken
candice said:
can i use a always on data goodybag in.my tablet
Ken replied:
Hi Candice,
Thanks for your comment. Yes, you can use your Always On goodybag in any device, including a 4G tablet.
Hope this helps!
Ken
lorna hunt said:
hi just a quick question, i have a £25 goody bag with gift gaff and this month i have used 120GB or so. all this has been in the UK am i going to get charged extra for this?
Ken replied:
Hi Lorna,
Thanks for your comment. No, you won’t be charged any extra for this. You get unlimited downloads on the £25 goodybag (albeit, with reduced speeds after the first 40GB per month).
Hope this helps,
Ken
Steven hurst said:
I must say thank you for this page. Your information has covered everything I needed to know. Im with virgjn media home broadband and have given them my 30 days notice. As I’ve just started using my phone for my internet use more and more. So I’ve decided to try giffgaff always on data £25 and try out tethering to my desktop computer as I don’t like doing my banking etc on my phone. I’m already on o2 mobile phone so everything should be straight forward. I don’t actually know how much data I normally use on my broadband so I’m hoping 40 gb is enough. But as this is not a contract it’s worth a try for one month to test it out
Clarence Chuah said:
Hi guys justs a quick question.
While roaming in Europe, and I limited to 3G speed or full 4G for 20GB? Planning to purchase the $25 plan.
Thanks
Clarence
Ken replied:
Hi Clarence,
Thanks for your comment. 4G roaming is available in the countries listed here. I believe download speeds are only reduced once you’ve used 40GB of data in one month.
Hope this helps,
Ken
chipz chipping said:
Hey, it appears that I’ve ended up in the ‘well..it’s not really, er, how do I put this, er, it’s not what we in the business call, erm, always on as such…?’ sort of area. After the first 20gb is used, I’m actually left with 0.4mbps download speed an long with a mighty 0.3mbps at 7.10pm!?WWWHHHAAAATTTTT?????
chipz chipping replied:
Sorry, yes your right it is now 4G.
Ken said:
Hi all,
Great news! You can now get 40GB of full-speed 4G data on the £25 goodybag. The article above has been updated to reflect this 🙂
Ken
Rich Baxter said:
This is not at all accurate. What GiffGaff don’t say until you read the small print (or even smaller print) is that after you use the 20GB, yes you drop to the slower speeds but you also have to pay 47p per MB used (yes, thats Mega Byte) after the 20GB. This is surely going to hurt a lot of people. I’ve already used over 10GB in 5 days so I am glad I read that as I’m stopping the service immediately.
This is for roaming in the EU.
Ken replied:
Hi Rich,
Thanks for your comment. As you say, giffgaff has a 20GB fair usage policy for roaming in Europe. If you’ve used more than 20GB of data, you’ll be surcharged 0.47p/MB (equivalent to £4.70/GB). However, this isn’t actually unique to giffgaff – most other mobile networks also have a fair usage policy for roaming in Europe!
Ken
steven moran said:
Why wont it let me buy a £25 goody bag as mine ran out
Ken replied:
Hi Steven,
I believe it should normally be possible to renew your goodybag early when you have less than 100 minutes, 100 texts or 100MB remaining on your goodybag. On the £25 Always-On goodybag, you should also be able to renew it early once you’ve used 20GB of data per month. If the system isn’t allowing you to do this, I recommend asking your question again over at giffgaff’s online community.
Ken
Amelia said:
So I’m confused. I want to get a data package that means I’ll always have data and for a cheap price which is why I chose giffgaff.
I’m unsure whether or not this is unlimited or not and if I’d be better getting the £20 deal.
Also is my bank card automatically charged every month or do I do that myself manually??
Ken replied:
Hi Amelia,
Thanks for your comment. giffgaff’s £25 goodybag is unlimited in some sense, though it’s worth being aware of the speed restriction once you hit 20GB per month. Personally, I’d probably go for the £20 goodybag unless you definitely know you need more than 20GB per month! You can then change your goodybag as required in subsequent months based on the amount of data you actually use.
With regards to how you’re charged for this, you’re not charged automatically every month by default. However, if you like, you can enable the automatic top-up & automatic goodybag purchase feature within your giffgaff account interface.
Hope this helps,
Ken
Ken said:
Hi all,
Just a quick note to say that giffgaff have updated their Always On goodybag. It has now gone up in price from £20 to £25 per month. However, you can now use 20GB of data at full 4G speeds, before the maximum speed is limited to 384kbps between 8am and midnight.
I’ve updated the article above to reflect these changes.
Ken
jim boonman said:
Dude 2. Giffgaff backend for data is shocking in some locations. All you can eat… yeah from a tap that drips once a minute.
Dan said:
Dude your forgetting to inform people that gigfgaff have a secret limit on always that means they can ban you from rebuying it ….. So one month you will be always on the next you won’t and they ban you for 3 months from purchasing always on …..three can not be compared to gigfgaff at all. On. Three you can use 100 or 200gb. No fuss …..on gigfgaff u dare even approach 15 to 20gb your banned although 384 kilobits. Isn’t gonna get you far and it’s not enough to stream. YouTube or Netflix I mean off gigfgaff labled the speed restriction in kylobytes you would realize that also vectone are doing amazing deals I get 30 gb pay as you go for a tenner a month
Sandra replied:
Three stops all their services once you reach 30gb. Be aware they will blame your post code area. They even stopped the calling service and everything once I reached 50gb. They give me 10-30kbps speed at most of the day. They are evil.