Unlimited data on trains, buses and ferries: price the day you will actually have

Netflix’s data-use guidance lists up to 1GB an hour for standard definition and up to 3GB for high definition under its High setting, with up to 7GB for Ultra HD. Its Medium setting is lower, at up to 0.7GB an hour. Six hours at 1GB or 3GB an hour means up to 6GB or 18GB respectively, before the rest of the phone’s use.

Those are settings-based examples, not measurements from your train. A downloaded programme doesn’t use mobile data to play, though fresh downloads, browsing and other background tasks still can. Open saved content offline before setting off so you know it finished downloading.

A stated week of six 0.5GB days and one 6GB streaming day totals 9GB; with a deliberate 25% margin, that’s 11.25GB. A 10GB fixed allowance falls short of that buffered example, while a 1GB-per-day service would reach its daily high-speed limit during the 6GB day even though other days are quiet.

Use Plan my trip with your dates, video-use choices and any sharing, or use our video data guide to check your own use. A daily allowance has to cover the busy day; a set trip allowance can be spread across quieter and busier days.

Japan’s seven-day 10Mbps plan does not routinely slow phone data because you have used a particular amount, but it includes only 6GB of sharing across the trip. The seven-day full-speed plan has no fixed plan speed limit or separate sharing limit. Both allow exceptional restrictions to protect the network, and neither promises a signal through every tunnel.

Indonesia unlimited has no published data limit that triggers a slowdown and no extra slowdown for heavy use. Thailand instead gives you 100GB at up to 10Mbps across the trip, then slows to 384kbps. Fourteen days using 6GB a day total 84GB before other use; eighteen days total 108GB and go past the faster allowance. Those are examples, not a typical bus passenger’s usage.

The local KDDI plans cover 11–21, 26 and 31 days in Japan. You can use unlimited data on your phone, but heavy use is reviewed over a rolling three-day period and may slow to around 1Mbps. The operator has not published a fixed number of gigabytes that triggers this slowdown.

Data shared with a laptop or another phone has its own limit for the trip: the number of plan days minus one, in GB. That gives you 13GB on the 14-day plan or 30GB on the 31-day plan. Once you use that sharing allowance, shared data may slow to around 128kbps.

The date you first use KDDI data counts as Day 1, even if you connect late in the day, and the plan ends at 11:59pm Japan time on its final day. There is also a start-by date supplied with the eSIM; an unused plan may start automatically when that date passes. Your phone needs to support KDDI, including LTE Band 18 or 26, and the local eSIM needs Data Roaming OFF. Follow its own setup details, because the shorter Japan plans work differently.

Save tickets, your arrival address and connection instructions offline. Coverage for a country does not promise a signal along every railway or out at sea, and a land-based plan does not include a ship’s maritime service.

Choose validity reaching the final travel day, save the setup email before flying and install after landing on working, steady Wi-Fi. For Indonesia and Thailand, don’t assume laptop sharing from their unlimited labels: supplier hotspot support and device/network limits remain unconfirmed.