A new 64 GB iPhone 8 could cost anywhere between £1,011 and £2,142 over two years, depending on your network deal and how much data you want per month.

While it’s not news that the more data you get, the more expensive it is, you might be surprised at the range of prices for the phone for any given amount of data.

For example, if you need about 8-10 GB of data a month, you could be paying anything between £1,035 for the cheapest deal (buying the phone for £699 and having two years of SIM-only connection with Three) and £1,441.75 for the most expensive (a £58 a month contract with EE).

Here, I did a graph. I’ll post links to my working soon in a spreadsheet. While this is just for the 64 GB iPhone 8, the shapes of everything are similar for the 256 GB and Plus versions.

Stuff to notice:

• Every provider apart from Three really doesn’t want you to sign up for a lot of data. EE and O2 offer particularly expensive deals if you flag yourself as a potentially heavy data user.
• There’s almost always a premium for paying less upfront. The contract deals (solid lines) sit well above the SIM-only + cost of phone deals (dashed lines) except in a few weird cases. On Three, this premium generally adds between 26% and 38% to the total cost over two years. There’s another particularly extreme example on Three which is the big kink in their cost curve. You can pay £79 upfront and get 100 GB data for £65 a month (total £1,639) or get the same phone and data with zero upfront and £81 a month (total £1,944). That’s a £305 charge to borrow £79 for two years – something like 190% annual interest. Seriously? If you’re paying £81 a month for your phone anyway, you’d be mad to go for that.
• You should probably note that there are “added value” extras in some networks’ plans, and I haven’t costed that in. If you want Spotify Premium, you’ll get that thrown in with Vodafone’s Red Entertainment plans, for example, which is worth £9.99 a month.  I just got a free pack of Hotel Chocolat chocs as a random freebie with Three. Go figure.

Ultimately, it’s worth doing a few sums before grabbing any new phone deal, especially at a low upfront price.

And I’m probably going to stick with my cost-saving strategy of buying a last-gen phone outright next time I need a new one!