Roaming vs Local SIM: How to Choose for Your Trip
International mobile costs can vary wildly depending on how you connect. The same destination can cost very differently depending on your home carrier's roaming rates versus buying a local SIM on arrival. This calculator helps you make a data-driven decision before your trip.
Daily Flat-Rate Roaming
Most major carriers offer a flat-rate daily roaming add-on, typically $5–$15/day, giving you access to your home plan's data abroad. This is convenient for short trips since there is no setup required and your home number stays active. For trips of 7+ days, the costs can add up quickly.
Local SIM and eSIM
Local SIMs are available at airports, convenience stores, and online. They typically offer much more data for less money. An eSIM (embedded SIM) works the same way but is activated digitally via QR code — no physical card swap needed. The tradeoff: your home phone number won't receive calls unless you forward them.
How to Use This Calculator
Enter the number of days, select your roaming type (daily flat or pay-per-use), and fill in your roaming fees. In the SIM section, enter the purchase price, data allowance, and expected daily usage. The calculator shows total estimated costs for both options and highlights the cheaper one.
Frequently Asked Questions
What if I exceed the SIM data cap?
Enter your expected daily data usage and the SIM's data cap. If your total usage exceeds the cap, the calculator applies your overage rate. If there is no overage (data speed throttled instead), enter 0 for the overage rate.
What about calls and SMS?
This calculator focuses on data costs, as most travelers now use apps (WhatsApp, FaceTime) for calls and messages over data. If you need voice calls, add your expected call costs to the roaming activation fee field.