Most travellers default to whichever option requires the least thought — usually their home carrier's roaming service — without realising it's frequently the most expensive of three genuinely viable choices. This estimator lines up home-carrier roaming, a local prepaid SIM bought on arrival, and a travel eSIM installed before departure, so the actual cost difference is visible before you commit to one, rather than discovering after the trip that a much cheaper option existed the whole time.
Home carrier roaming is the path of least resistance — your existing number and plan simply extend to work abroad with no new SIM card, no shop visit, and no risk of losing your usual number for the trip. That convenience typically comes at the steepest per-gigabyte cost of the three options, particularly on traditional pay-as-you-go roaming rates rather than a carrier's dedicated travel pass, if one is offered. A local prepaid SIM bought after arrival is usually the cheapest route for data-heavy trips, but it requires your phone to be carrier-unlocked, a working local shop or SIM vending machine on arrival, and it temporarily replaces your home number, meaning anyone trying to reach you on your usual number won't get through unless you have call forwarding or a secondary way to stay reachable. A travel eSIM installed digitally before you even leave home splits the difference well for many travellers — competitive data pricing similar to a local SIM, active before you land, with no physical SIM swap — provided your specific phone model supports eSIM technology and your travel dates fall within what your chosen eSIM plan covers.
The right choice depends heavily on how much data you'll genuinely use, which is easy to either overestimate or badly underestimate. Mostly using WiFi at accommodation and only needing maps and messaging on the go uses meaningfully less data than someone planning to stream video or make video calls throughout the trip. Checking your own typical monthly data usage at home, then scaling it to your trip length, is a more reliable starting estimate than guessing a flat number, since usage patterns vary enormously between travellers.
For very short trips of just a few days, the convenience of home-carrier roaming or a pre-installed eSIM often outweighs a marginal saving from hunting down a local SIM vendor on arrival. For longer trips or heavy data use, the larger absolute saving from a local SIM or a well-priced eSIM plan becomes worth the small extra setup effort. Run your own trip's numbers through this estimator with real prices — found via a quick search for "[destination] tourist SIM price" or your chosen eSIM provider's own pricing page — rather than relying on this tool's default placeholder figures.
One final point: whichever option you choose, download offline maps and any essential travel documents to your phone before you land, so a brief gap in connectivity while switching SIMs or activating an eSIM doesn't leave you stranded without directions or your boarding pass.
Yes, generally — a phone still locked to your home carrier typically can't accept a different carrier's physical SIM card. Check with your home carrier whether your phone is unlocked before planning around a local SIM purchase.
An eSIM is a digital SIM built into supporting phones that can be activated remotely without inserting a physical card. Most flagship phones released in the last several years support it, but check your specific model's specifications, since many budget and older phones don't.
Yes, while the local SIM is active, calls and texts to your home number typically won't reach your phone unless you've arranged call forwarding in advance, which is worth setting up if you need to stay reachable on your usual number.
No, they're placeholder examples meant to illustrate the comparison — replace them with your home carrier's actual roaming rate and real local SIM/eSIM prices for your specific destination before relying on the result.