eSIM vs Local SIM Cost Comparator

Why travelers overpay for mobile data

Most people buy travel data the way they buy snacks at the airport — in a hurry, at the worst possible price. The default is usually roaming on your home plan, which can cost ten dollars or more per gigabyte, or grabbing whatever SIM the arrivals-hall kiosk pushes at you. Neither option is chosen; both just happen to you. A little comparison shopping before you fly routinely saves twenty to fifty dollars on a two-week trip, and it is the difference between rationing Google Maps and using your phone normally.

How the comparator does the math

First it works out your total data need: trip days multiplied by your expected daily use. Then, for each plan, it figures out how many packs you actually have to buy. That is the part people get wrong, because packs are limited by two things at once: the data allowance and the validity period. The number of packs is the larger of (total need ÷ allowance, rounded up) and (trip days ÷ validity, rounded up). A 7-day eSIM on a 14-day trip needs two packs even if the data would have been plenty. Finally it divides each option's total cost by your real data need to get an effective price per gigabyte, and declares the cheaper option.

Worked example

Take a 14-day trip at 1 GB per day — 14 GB total. An eSIM costs $20 for 10 GB valid 15 days: the 10 GB allowance falls short of 14 GB, so you need 2 packs = $40 for 20 GB bought. A local SIM costs $15 for 20 GB valid 30 days: one pack covers the whole trip = $15. The local SIM wins by $25, at $1.07 per GB versus the eSIM's $2.86 per GB. Notice the headline prices told the opposite story — the $15 plan beat the $20 plan by a mile once packs and validity were counted properly.

Practical tips

Always check that a plan's validity covers your whole trip, not just its data allowance. eSIMs need no physical swap — most recent phones run the travel eSIM alongside your home SIM in dual-SIM mode. Local SIMs are often cheapest but may need passport or ID registration, and the shop may charge an activation fee — add it to the price field. Budget about 20% more data than you think: navigation, photo backups and hotspot tethering add up fast. And compare the effective price per gigabyte, never the headline pack price.