Monthy vs Three
Monthy vs a Three data add-on
Three's One Day Boost is the most expensive single day in this comparison at £9, and it expires at midnight rather than 24 hours after you buy it — buy at 8pm and you've got four hours. The Monthly Boosts are better value per gigabyte but they renew automatically, which is the exact thing most people are trying to avoid when they're just short a few days.
Get me to reset dayWhat Three data add-on actually sells
Three Pay Monthly add-ons: One Day Boost (unlimited, expires midnight) £9; One Month Boost (unlimited until your bill renews) £25; recurring Monthly Boosts at £6 for 1GB, £8 for 3GB, £10 for 5GB, £13 for 10GB, £20 unlimited — all of which renew automatically until cancelled.
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 | Three data add-on |
|---|---|---|
| 1 day | £3.50 | £9.00 — and it dies at midnight, not in 24 hours |
| 3 days | £6.75 | £27.00 for three One Day Boosts, or an £8+/month recurring Boost |
| 5 days | £9.75 | A recurring Monthly Boost from £8–£13/month |
| 7 days | £11.95 | A recurring Monthly Boost, or £25 for the One Month Boost |
Side by side
| Monthy | Three data add-on | |
|---|---|---|
| What you're buying | A fixed number of days, then it's over | A day that ends at midnight, or a subscription |
| Does it renew? | Never. One payment, no card stored for later | Monthly Boosts renew automatically until you cancel |
| A three-day gap | See the table above | £27 in day boosts, or start a subscription |
| Do you need to be a Three customer? | No — any network, any unlocked eSIM phone | Yes |
| Setup | eSIM, live in a couple of minutes | Instant in My3 |
| Keeps your number | Yes — data only, sits alongside your normal SIM | Yes — it's your existing line |
When Three data add-on is the better buy
- You need unlimited data for a few hours this evening and don't want to install anything — £9 is steep but it's one tap.
- You'll realistically keep needing more data every month. A recurring Boost is the right shape for a recurring problem; Monthy isn't.
- Your phone doesn't support eSIM.
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
- Does Three's One Day Boost really expire at midnight?
- Yes — Three's own page says it expires at midnight rather than lasting a full 24 hours. A Monthy day runs 24 hours from activation.
- Will Monthy renew like a Monthly Boost?
- No, and we've deliberately built it so it can't. You pay once for the days you chose. When they run out, Monthy is done.
- Can I use Monthy on a Three contract?
- Yes. It's a data-only eSIM alongside your Three SIM. Your number, calls and texts stay on Three.
- What if my gap is longer than a fortnight?
- Then we'll tell you not to buy from us. Past about two weeks, a rolling monthly SIM is genuinely cheaper and we'd rather say so.
Where these numbers came from
Prices checked 2 August 2026. Other networks change their prices without telling us — always check theirs before you buy.