This is one of those posts where the conclusion isn’t the surprise. The surprise is the size of the gap.
The trip we costed
To make this concrete: a one-week trip to Japan. Tokyo, Kyoto, Osaka. Maps, Google Translate, photo backups, ride-share, WhatsApp, three video calls with home. Total data usage: about 5 GB, which is bang in the middle of what most travellers actually use.
We costed it across five home carriers (Telstra, Optus, Vodafone AU, EE in the UK, AT&T in the US) and compared each one against the equivalent SimKit Japan plan.
The numbers
| Carrier / option | Cost for 7 days, ~5 GB | Notes |
|---|---|---|
| Telstra International Day Pass | A$70 | $10/day, capped at FUP after 1 GB/day |
| Optus Roaming | A$70 | $10/day for 7 days |
| Vodafone AU Roaming | A$35 | $5/day — the cheapest big-carrier option |
| EE Roam Abroad (UK) | £42 (~A$80) | £6/day day pass |
| AT&T International Day Pass | US$84 (~A$130) | $12/day |
| SimKit Japan 5 GB / 30 days | A$11.90 | No fair-use throttling, tethering allowed |
The verdict
SimKit comes in at A$11.90. The cheapest carrier roaming option (Vodafone AU) comes in at A$35 — nearly 3× the price. The most expensive (AT&T) is more than 10×. And the Telstra and Optus options throttle you to 1 GB/day before slowing speeds, which on a maps-and-translate-heavy trip you’ll hit by lunchtime on day one.
The reason isn’t magic. It’s structure: when you roam, your home carrier is paying the foreign carrier wholesale and adding a margin. When you buy a SimKit eSIM, you’re effectively skipping the home carrier middleman — our network partner connects directly to the same Japanese network towers, at wholesale-plus-a-thin-margin.
When roaming actually wins
One scenario only: a one- or two-day stopover where setup time matters more than money. If you’re in Tokyo for 18 hours between flights and your home plan includes a free day of roaming, just use that. The math only tips when you’re abroad long enough to recoup the setup minutes — which is basically any trip 2+ days.
Want to do this on your trip?
Have a look at our Japan plans, or browse other destinations. The whole flow from buying to installed takes about 60 seconds.