Cheapest Unlimited Data SIM Deals UK | PAYM And PAYG

September 20, 2025 by Tom

Searching for the cheapest possible unlimited data SIM you can buy in the UK?

Below, you’ll find the cheapest SIM deals with unlimited usage on the market at the moment.

Contents

Cheapest pay monthly unlimited data SIM deals
Cheapest pay as you go (month to month) unlimited data SIM deals

Cheapest pay monthly unlimited data SIM deals

12 month contract

Unlimited Texts
Unlimited Calls

Cashback paid automatically: £53.00
Recommend a Friend and Earn Rewards
No speed caps
+ More

Unlimited Monthly Data

£11.58 Average Monthly Cost

£16.00 Per Month

12 month contract

Unlimited Texts
Unlimited Calls

Cashback paid automatically: £40.00
Prices that stay fixed
Free Roaming up to 30GB
+ More

Unlimited Monthly Data

£11.67 Average Monthly Cost

£15.00 Per Month

12 month contract

Unlimited Texts
Unlimited Calls

Cashback paid automatically: £36.00
Recommend a Friend and Earn Rewards
No speed caps
+ More

Unlimited Monthly Data

£12.00 Average Monthly Cost

£15.00 Per Month

24 month contract

Unlimited Texts
Unlimited Calls

Cashback paid automatically: £50.00
Recommend a Friend and Earn Rewards
No speed caps
+ More

Unlimited Monthly Data

£14.92 Average Monthly Cost

£17.00 Per Month

24 month contract

Unlimited Texts
Unlimited Calls

Unlimited Data
No annual price increase
+ More

Unlimited Monthly Data

£15.00 Average Monthly Cost

£15.00 Per Month

12 month contract

Unlimited Texts
Unlimited Calls

Data Rollover
Free Roaming up to 30GB
+ More

Unlimited Monthly Data

£16.00 Average Monthly Cost

£16.00 Per Month

24 month contract

Unlimited Texts
Unlimited Calls

Data Rollover
Free Roaming up to 30GB
+ More

Unlimited Monthly Data

£16.00 Average Monthly Cost

£16.00 Per Month

12 month contract

Unlimited Texts
Unlimited Calls

Unlimited Monthly Data

£17.00 Average Monthly Cost

£17.00 Per Month*

*Monthly cost will increase by approx. £1-£1.50 each April

12 month contract

Unlimited Texts
Unlimited Calls

Unlimited Monthly Data

£17.00 Average Monthly Cost

£17.00 Per Month*

*Monthly cost will increase by approx. £1-£1.50 each April

12 month contract

Unlimited Texts
Unlimited Calls

Unlimited Monthly Data

£17.00 Average Monthly Cost

£17.00 Per Month*

*Monthly cost will increase by approx. £1-£1.50 each April

Cheapest pay as you go (month to month) unlimited data SIM deals

1 month contract

Unlimited Texts
Unlimited Calls

Wi-Fi Calling
eSIM Compatible
+ More

Unlimited Monthly Data

£9.00 Average Monthly Cost

£9.00 Per Month*

*Monthly cost will increase by approx. £1.50 each April

1 month contract

Unlimited Texts
Unlimited Calls

Unlimited Data
No annual price increase
+ More

Unlimited Monthly Data

£15.00 Average Monthly Cost

£15.00 Per Month

1 month contract

Unlimited Texts
Unlimited Calls

Recommend a Friend and Earn Rewards
No speed caps
+ More

Unlimited Monthly Data

£15.00 Average Monthly Cost

£15.00 Per Month

1 month contract

Unlimited Texts
Unlimited Calls

Data Rollover
Free Roaming up to 30GB
+ More

Unlimited Monthly Data

£15.00 Average Monthly Cost

£15.00 Per Month

1 month contract

Unlimited Texts
Unlimited Calls

Data Rollover
Free Roaming up to 30GB
+ More

Unlimited Monthly Data

£16.00 Average Monthly Cost

£16.00 Per Month

1 month contract

Unlimited Texts
Unlimited Calls

Wi-Fi Calling
eSIM Compatible
+ More

Unlimited Monthly Data

£16.00 Average Monthly Cost

£16.00 Per Month

1 month contract

Unlimited Texts
Unlimited Calls

Unlimited Monthly Data

£18.00 Average Monthly Cost

£18.00 Per Month

1 month contract

Unlimited Texts
Unlimited Calls

Unlimited Monthly Data

£25.00 Average Monthly Cost

£25.00 Per Month

1 month contract

Unlimited Texts
Unlimited Calls

Unlimited Monthly Data

£25.00 Average Monthly Cost

£25.00 Per Month

1 month contract

Unlimited Texts
Unlimited Calls

Unlimited Monthly Data

£25.00 Average Monthly Cost

£25.00 Per Month

About the author

Tom

Tom is the founder of Green Smartphones. You’ll find him writing about phones on the Green Smartphones blog, or talking about SIM deals and mobile networks on our YouTube channel. He’s the Android expert on the team – currently using a Google Pixel 9, recently upgrading from a very long-suffering Note 20 Ultra. When he’s not working on Green Smartphones, you’ll find him playing football or hiking.

Leave a Comment Cancel reply