Monthy vs O2
Monthy vs an O2 Data Bolt On
This is the comparison that made us build Monthy. O2's Data Bolt Ons are priced per gigabyte and they are not cheap — £12.50 for a single gigabyte, £24.99 for 8GB. If you've got a few days to go and you use your phone normally, a Monthy costs less than O2's smallest useful bolt-on and doesn't leave you rationing.
Get me to reset dayWhat O2 Data Bolt On actually sells
O2 Data Bolt Ons are a one-off payment for a fixed amount of data valid for just over 30 days: 100MB £5.50, 500MB £8.50, 1GB £12.50, 2GB £15.50, 4GB £18.99, 8GB £24.99, 12GB £32.50. Added through My O2.
What a gap costs
Monthy prices come straight from our live price list. Theirs were read off their own site on 2 August 2026.
| Days to your reset day | Monthy | O2 Data Bolt On |
|---|---|---|
| 1 day | £3.50 | £12.50 for 1GB — the smallest bolt-on that covers a normal day |
| 3 days | £6.75 | £15.50 for 2GB, or £18.99 for 4GB |
| 5 days | £9.75 | £18.99 for 4GB |
| 7 days | £11.95 | £24.99 for 8GB |
Side by side
| Monthy | O2 Data Bolt On | |
|---|---|---|
| What you're buying | Days — 1GB of full-speed data refreshed every 24 hours | A fixed lump of gigabytes to eke out |
| What happens at the end | It stops by itself | Bolt On expires after ~30 days |
| Cost of a light week | See the table above | £18.99–£24.99 |
| Do you need to be an O2 customer? | No — any network, any unlocked eSIM phone | Yes |
| Setup | eSIM, live in a couple of minutes | Instant in My O2 |
| Keeps your number | Yes — data only, sits alongside your normal SIM | Yes — it's your existing line |
When O2 Data Bolt On is the better buy
- You genuinely only need a few hundred megabytes to get through. £5.50 for 100MB is poor value per gigabyte but it's a small amount of money.
- Your phone doesn't do eSIM, or you'd rather not touch your settings at all.
- You want the data to sit on your existing O2 number with nothing else to manage.
Get me to reset day
30 secondsWhen does your normal data reset?
Or just tell us how long
Pick your reset day and we'll work out the rest — you'll see the exact price before you pay anything.
Nothing arrives in the post. Monthy is a second data connection your phone downloads itself — it takes about a minute, and your normal SIM stays exactly where it is.
Common questions
- Why is a Monthy cheaper than an O2 bolt-on?
- Because we're not selling you gigabytes at a markup. We buy wholesale UK data by the day and sell you the days you need. O2's bolt-ons are priced to make running out expensive.
- Does Monthy work if I'm on O2?
- Yes. It's a separate data-only eSIM. Your O2 SIM keeps your number, calls and texts; your phone uses Monthy for data until your allowance resets.
- How much data do I get?
- 1GB at full speed every 24 hours, which covers normal use — maps, messaging, socials, music. After that daily gigabyte it slows down until the next day rather than stopping.
- Will O2 charge me anything for using Monthy?
- No. You're not changing anything on your O2 account. Nothing is added, nothing is cancelled.
Where these numbers came from
Prices checked 2 August 2026. Other networks change their prices without telling us — always check theirs before you buy.