Calculate roaming data charges and compare with a local SIM.
Roaming cost is dominated by data beyond the bundle, where per-gigabyte rates are many times local prices. Once usage exceeds the bundle by a few gigabytes a local SIM almost always wins. A local eSIM removes the need to swap physical cards, which has made the comparison worth making even for short trips.
Roaming Data Cost
Roaming cost = bundle cost + data beyond the bundle × cost per additional GB
Roaming cost = bundle cost + data beyond the bundle × cost per additional GB Roaming cost is dominated by data beyond the bundle, where per-gigabyte rates are many times local prices. Once usage exceeds the bundle by a few gigabytes a local SIM almost always wins.
A local eSIM removes the need to swap physical cards, which has made the comparison worth making even for short trips.
This calculator takes 5 inputs: Data used, Data included in the roaming bundle, Cost per additional GB, Roaming bundle cost, Local SIM cost for the same data. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.