Plan roaming data needs and the bundle size a trip requires.
Wi-fi offload dominates the calculation, since accommodation wi-fi typically handles half or more of usage. Navigation is the one category that reliably needs cellular data. Downloading offline maps before travelling removes the largest unavoidable component of roaming data use.
Mobile Data Roaming
Data needed = (daily use × (1 − wi-fi offload) + navigation data) × days
Data needed = (daily use × (1 − wi-fi offload) + navigation data) × days Wi-fi offload dominates the calculation, since accommodation wi-fi typically handles half or more of usage. Navigation is the one category that reliably needs cellular data.
Downloading offline maps before travelling removes the largest unavoidable component of roaming data use.
This calculator takes 5 inputs: Trip length, Daily data use, Share offloaded to wi-fi, Navigation data per day, Bundle size available. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.