International Roaming Cost Calculator
International mobile phone costs can be a significant and surprising travel expense. This calculator estimates the cost of your carrier's international roaming plan for your trip and compares it against the estimated cost of purchasing a local SIM card at your destination, so you can choose the more cost-effective option before you travel.
Carrier international roaming plan
Local SIM comparison
Roaming cost formula
Carrier plan cost = Daily plan fee x Days + max(0, Daily data use - Plan data) x Days x Overage rate per GB
Local SIM cost = SIM card cost + Top-up costs
Savings = |Carrier plan cost - Local SIM cost|
If your daily data usage is less than the plan's included data, no overage applies and the carrier plan cost is simply the daily fee multiplied by days. Overage charges apply only if usage exceeds the daily allotment.
Options for international mobile connectivity
- Carrier international day passes: simple, no number change, but often $10/day with throttled data after a daily cap.
- Local SIM card: cheapest for trips of 1 week or more; requires an unlocked phone; temporary number change.
- International eSIM: no physical SIM swap needed; available from providers such as Airalo and Ubigi; typically competitive with local SIM pricing.
- Pocket Wi-Fi device: provides a shared hotspot for multiple devices; useful for groups; requires managing a separate device and battery.
- Wi-Fi only (no SIM): viable for leisure travellers who can rely on hotel and cafe Wi-Fi; requires messaging apps (WhatsApp, iMessage over Wi-Fi) for communication.
International roaming cost calculator: frequently asked questions
How are international roaming charges calculated?
International roaming charges consist of three components: data charges (per MB or per GB, or a flat daily/weekly plan fee), voice call charges (per minute for outgoing and incoming calls, which may differ), and SMS charges (per text message sent or received). Most major US carriers now offer daily international plans ($5 to $15 per day) that include a data allotment and unlimited calls and texts, which is often simpler than paying per-use rates.
Is it cheaper to use a local SIM card when travelling internationally?
For trips of one week or more, a local SIM card (purchased at the destination) is typically significantly cheaper than carrier roaming plans. A local prepaid SIM with 5 to 15 GB of data typically costs $10 to $30 in most countries. The savings versus $10 to $15 per day for a carrier international plan can be substantial. The tradeoff is that you temporarily use a different phone number, which may inconvenience contacts trying to reach you on your home number.
What is the FCC rule on international roaming bill shock?
The US Federal Communications Commission (FCC) requires wireless carriers to provide customers with alerts when they are approaching significant international roaming charges. The FCC's International Bill Shock rule requires carriers to send a notification when international roaming data charges reach $100 in a billing cycle, and again at each subsequent $100 increment, to prevent unexpected large bills.
Can I use Wi-Fi calling to avoid roaming charges?
Yes. If your carrier supports Wi-Fi calling, you can make and receive calls over a Wi-Fi connection at no additional charge (the call is billed as a domestic call). This is effective in hotels, cafes, and other locations with free Wi-Fi. However, it requires an active Wi-Fi connection and may not work for all call types. Data roaming still applies for internet usage when not on Wi-Fi.
What is a good daily data usage estimate for international travel?
Typical daily mobile data usage for a traveller with moderate smartphone use (maps, messaging, email, social media, but no video streaming) is 100 to 500 MB per day. Heavy users who stream video or make frequent video calls may use 1 to 3 GB per day. Light users who rely primarily on Wi-Fi and use data only for maps and messaging may use 50 to 150 MB per day.
Official sources
- FCC International Bill Shock rules and consumer guides: fcc.gov international roaming.
- FCC consumer guide on reducing phone bills while travelling: fcc.gov reduce phone bill.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.