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How much mobile data do you really need?

Many people pay for more data than they use, and some pay for too little and run out. Here's how to find the right amount, and how to switch to a SIM-only plan while keeping your number.

Last updated: November 2026

Step 1: check what you actually use

Your phone keeps a record of how much mobile data you've used. Look in your phone's settings under Mobile data or Data usage. Your network's app or online account will usually show your monthly usage too.

Look at your last three months, not just one, so a holiday or a busy month doesn't skew the picture. Then add a little headroom.

Step 2: know what uses the most data

  • Heavy: streaming video (TV, films, video apps), video calls, hotspotting your laptop, and downloading large apps or updates over mobile data.
  • Medium: streaming music and podcasts, scrolling social media with lots of videos, and maps and navigation on long journeys.
  • Light: messaging, email and general web browsing.

If most of your streaming happens at home or work on Wi-Fi, you probably need far less mobile data than you think.

Step 3: pick a plan that fits

  • Mostly on Wi-Fi? A smaller data allowance is usually enough, and it's often the cheapest.
  • Regular streaming or travel on the go? Choose a mid-sized allowance with some headroom.
  • Heavy streaming, hotspotting, or you don't want to think about it? An unlimited plan may be simpler. Check for fair-use limits and any speed caps.

30-day or 12+ months? 30-day rolling SIM-only plans let you change or leave each month, which is useful while you work out what you need. Longer plans can be cheaper per month but tie you in. Check any price rises: for contracts taken out since 17 January 2025, rises must be set out upfront in pounds and pence.

How to switch and keep your number

Ofcom's "text to switch" rules make this quick and free:

  1. From the phone you want to switch, text "PAC" to 65075. You'll get your switching code (PAC) by text, usually within a minute, along with any early termination charges. The code is valid for 30 days.
  2. Sign up for your new SIM-only plan and give the new network your PAC.
  3. Your new network must complete the switch within one working day of receiving your PAC.

Want a new number instead? Text "STAC" to 75075. Not sure if you're still in contract? Text "INFO" to 85075 to find out, without starting a switch.

You won't be charged for notice periods that run past your switch date, as long as you give the new provider your PAC or STAC.

Can I keep my phone?

Yes. UK networks are banned from selling locked phones, so your handset should work with a new SIM. If you're still paying off your phone, keep making those payments as agreed. Moving your airtime to a SIM-only plan doesn't end a separate phone payment plan.

Ready to switch?

See our hand-picked deals. Every one shows the reward you'll get, to keep as a shop voucher or donate to charity.

See SIM-only deals

Sources

This guide is general information, not advice about your personal situation. Rules can change, so check the latest details with your provider or the regulator.