On au and UQ mobile plans with no free days of au海外放題, it costs ¥800 per 24 hours booked ahead in the United States, South Korea, Taiwan and Thailand, so 7 x ¥800 = ¥5,600 ($35.63) for a week. Travel periods of 6 to 8 days used a median of 1.38 GB in Bcengi's 2026 sample. Paying as you go, that trip's 1.38 GB costs $2.50 in South Korea at $1.81/GB, metered by the KB. Bcengi is about 14 times cheaper for this trip.
This page is for au and UQ mobile plans that get no free days of au海外放題. Prices are as listed on au's website, read October 3, 2026.
What au charges for data abroad
- au海外放題 booked ahead from Japan in au's app: au charges ¥800 per 24 hours in the United States (including Hawaii), South Korea, Taiwan and Thailand, and ¥1,000 per 24 hours in France.
- au海外放題 without booking: au charges ¥1,200 per 24 hours in every destination, so 7 x ¥1,200 = ¥8,400 ($53.44) for a week.
- au charges for every 24 hours you use it, however little data those hours use. The same au海外放題 prices apply on UQ mobile.
What a 7-day trip costs: au海外放題 or paying as you go
Paying as you go with Bcengi, a trip costs what its data costs. Each line below is a model for a trip of 6 to 8 days: the median (1.38 GB) and the 90th percentile (6.50 GB) from the usage report, times the country's rate on October 3, 2026.
- United States rates: a median 7-day trip (1.38 GB at $1.68/GB) costs $2.32 with Bcengi; at the 90th percentile (6.50 GB at $1.68/GB), $10.92. Against au海外放題 booked ahead (7 x ¥800 = ¥5,600 with au), the median trip is about 15 times cheaper and the 90th percentile trip about 3.5 times cheaper.
- South Korea, Taiwan and Thailand: a median 7-day trip (1.38 GB at $1.81/GB) costs $2.50 with Bcengi; at the 90th percentile (6.50 GB at $1.81/GB), $11.77. Against au海外放題 booked ahead (7 x ¥800 = ¥5,600 with au), the median trip is about 14 times cheaper and the 90th percentile trip about 3 times cheaper.
- France rates: a median 7-day trip (1.38 GB at $1.19/GB) costs $1.64 with Bcengi; at the 90th percentile (6.50 GB at $1.19/GB), $7.74. Against au海外放題 booked ahead (7 x ¥1,000 = ¥7,000 with au), the median trip is about 27 times cheaper and the 90th percentile trip about 6 times cheaper.
In every destination listed, even a 7-day trip at the 90th percentile costs less paying as you go than a week of au海外放題 booked ahead (¥5,600 with au, ¥7,000 in France).
For how bundles and pay as you go compare, see bundles vs pay as you go.
What you get with Bcengi
- One reusable eSIM: install it once and use it on every trip.
- A balance that never expires: what one trip does not use is there for the next.
- No plan to pick: you never guess a size before you travel.
- Top up any time, by hand or with auto-refill.
- Your phone number stays on your home SIM for calls and texts; Bcengi is data only.
au and UQ mobile overseas data questions
How much does au海外放題 cost?
Booked ahead, au charges ¥800 per 24 hours in the United States, South Korea, Taiwan and Thailand and ¥1,000 in France; without booking, au charges ¥1,200 per 24 hours.
Can I use au海外放題 on UQ mobile?
Yes. au's page offers au海外放題 to UQ mobile customers at the same prices.
How do I use a travel eSIM instead of au海外放題?
Install the eSIM before you leave, set it as your data line, and turn data roaming off for your au or UQ mobile line so it does not use data abroad. See turn roaming off on your home line.
How these figures were measured
The usage figures come from Bcengi's 2026 International Mobile Data Usage Report: a stratified random sample of 10,000 travel periods, with usage from January 1 to September 30, 2026. The figures cover every destination in the sample, not one country.
Each trip cost on this page is a model, not a bill: the GB a trip used times the per-GB rate on our pricing page on October 3, 2026. Rates can change; the pricing page always has the current ones.
Yen prices are converted to US dollars at the Federal Reserve's rate for September 25, 2026, 157.18 yen per dollar.
Updated October 3, 2026. Sources: au's au海外放題 page; Federal Reserve exchange rates; Bcengi 2026 International Mobile Data Usage Report; Bcengi pricing page.
