Unlimited Data SIM Cards UK
Truly Unlimited Plans from ~£20/month
Compare unlimited data SIMs from Giffgaff and Lebara. 5G included at no extra cost, rolling 30-day plans, no contract and no credit check — ideal for streaming, hotspotting and replacing home broadband.
From ~£20/month
Cheapest unlimited data plans
No Contract
Cancel or change plan any month
5G Included
Fastest speeds at no extra cost
Who Needs an Unlimited Data SIM?
Unlimited plans cost more upfront but work out cheaper than paying overage fees — if you actually use the data.
Stream Without Counting GB
An hour of HD video uses roughly 3GB. If you stream daily on your commute, a 20GB plan disappears fast — unlimited removes the mental arithmetic.
Hotspot Your Laptop
Working from cafés, trains or client sites? Tethering eats 1-2GB per workday. Unlimited data turns your phone into a genuine mobile office.
Replace Home Broadband
In a flat with slow or expensive fixed-line broadband? An unlimited 5G SIM in a router can deliver faster speeds with no installation and no 18-month contract.
No Bill Shock
With Giffgaff and Lebara you can't run up overage charges — when the allowance is gone on a capped plan you simply top up or wait. Unlimited makes it a non-issue.
No Credit Check
Rolling 30-day unlimited plans from both networks need no credit check, unlike 12-24 month unlimited contracts from the big networks.
5G at No Extra Cost
Both networks include 5G on unlimited plans where coverage is available — no premium 5G tariff, no speed-cap upsell.
Unlimited Data SIM Only Deals by Network
Giffgaff Unlimited Data (O2 Network)
Unlimited goodybags on O2's network — change or cancel every month.
- ✓ Unlimited data — £20/month on promotion (normally £35)
- ✓ Unlimited UK calls & texts included
- ✓ O2 network - 99% UK coverage
- ✓ 5G included at no extra cost
- ✓ EU-zone roaming — use up to 5GB of your allowance
- ✓ No contract, no credit check
Lebara Unlimited Data (Vodafone Network)
Unlimited plans on Vodafone's network with international minutes included.
- ✓ Unlimited data plans from around £25/month
- ✓ Unlimited UK calls & texts
- ✓ International minutes to 50+ countries on many plans
- ✓ 5G included where available
- ✓ EU & India roaming, up to 30GB fair use
- ✓ Rolling 30-day plans, no credit check
Unlimited Data SIMs Compared
Side-by-side look at the two no-contract networks offering unlimited data, so you can pick the right unlimited plan.
| Feature | Giffgaff (O2 network) | Lebara (Vodafone network) |
|---|---|---|
| Unlimited data from | £20/month promo (normally £35) | ~£25/month |
| Data options | 1GB to unlimited | 2GB to unlimited |
| Calls & texts | Unlimited UK on all plans | Unlimited UK on all plans |
| International calls | Pay-as-you-go rates | 100+ mins to 50+ countries on many plans |
| 5G | Included at no extra cost | Included at no extra cost |
| EU roaming | Included on qualifying plans | Included allowance |
| Contract | None — rolling 30 days | None — rolling 30 days |
| Credit check | None | None |
Best for most people: Giffgaff (O2 coverage, flexible goodybags). Best for international calling: Lebara (50+ countries included).
Unlimited Data SIM Pricing
Typical unlimited data pricing, plus the high-data alternative worth comparing before you commit to unlimited.
Giffgaff Unlimited
O2 network, change plan monthly
£20/month promo (norm. £35)
- ✓ Unlimited data
- ✓ Unlimited calls & texts
- ✓ 5G included
- ✓ No contract
Lebara Unlimited
Vodafone network, international minutes in
~£25/month
- ✓ Unlimited data
- ✓ Unlimited calls & texts
- ✓ 5G included
- ✓ EU roaming
Alternative: ~100GB
Often enough — and cheaper than unlimited
£15–£20/month
- ✓ ~100GB data
- ✓ Unlimited calls & texts
- ✓ 5G included
- ✓ Save ~£5-£10/month vs unlimited
Prices are indicative and may change — always confirm current pricing on the network's site before ordering.
Unlimited Data SIMs: FAQs
What is an unlimited data SIM?
It's a SIM only plan with no data cap — you can use as much data as you like each month for a fixed price. Unlimited plans from Giffgaff and Lebara also include unlimited UK calls and texts, on rolling 30-day terms.
Is unlimited data really unlimited?
For normal phone use, yes. Networks apply fair use and traffic management policies (for example, prioritising traffic in congested areas or restricting resale/tethering at scale), but for personal use — streaming, hotspotting, browsing — your speeds aren't capped.
How much is unlimited data in the UK?
No-contract unlimited data SIMs from Giffgaff and Lebara start from around £20/month. That's typically far cheaper than unlimited plans bundled with a new handset from the major networks.
Can I hotspot with an unlimited data SIM?
Yes — tethering your laptop or tablet is fine on both networks for personal use. If you need connectivity for a router or multiple devices full-time, see our data only SIM guide.
Can I put an unlimited SIM in a 4G/5G router?
Yes, any SIM works in a router. For a permanent home-broadband replacement, a dedicated data only SIM is often the cleaner choice, but an unlimited SIM does the same job.
What is the cheapest unlimited data SIM only deal in the UK?
The cheapest no-contract unlimited data SIM only deals come from Giffgaff and Lebara, starting around £20/month — both on rolling 30-day terms with 5G included. That's typically £10-£20/month less than unlimited plans on a handset contract from the major networks.
Ready to Go Unlimited?
Order a free SIM, activate, and switch to unlimited data on a rolling monthly basis