Guide to AT&T International Plans in Japan

Heading to Japan and wondering if your AT&T plan will work just like it does back home?

AT&T offers two international options that can be used in Japan:

• International Day Pass (IDP)
• Pay-per-use rates (Pay as you go)

While these options do work abroad, they can get expensive depending on your current plan and the length of your trip.

In this article, we’ll break down AT&T’s international roaming options and introduce a more budget-friendly alternative: prepaid SIM and eSIM plans made for travelers in Japan.

Let’s dive in!

Table of Contents

1. Does AT&T Work in Japan?

Yes, AT&T customers can use their phones in Japan through international roaming. AT&T is most likely partnered with one of Japan’s three main providers.

AT&T’s Coverage in Japan

On AT&T’s coverage map, most of Japan shows up in green, which means you should get a signal in most places. 5G isn’t guaranteed everywhere, but you should have 4G or at least 3G, especially in cities and well-traveled areas.

Now, let’s take a closer look at AT&T’s international plans.

2. AT&T International Plans in Japan

Wondering how your AT&T plan works in Japan and how it compares? Here are the details for each plan below:

Scroll right for more (on mobile) →→

（Excluding Tax）

How it works:

• International Day Pass (IDP): Sign up for the IDP before your trip or it will be automatically added once you land in Japan.
• Pay-per-use rates: Those without an IDP or an eligible plan will automatically be charged the fees in the table above when they go abroad.

With AT&T’s International Day Pass, you can use your regular plan abroad for $12 per day. Charges cap at $120 per month/bill period for the IDP.

Connection Speeds⚡

AT&T doesn’t publish specific connection speeds for international roaming or the International Day Pass (IDP) on its website. While the IDP itself doesn’t have a daily high-speed data cap (e.g. 5GB/day), your actual speeds can vary depending on two key factors:

• Network congestion in Japan
• The details of your AT&T domestic plan

A quick breakdown:

AT&T’s unlimited plans differ when it comes to high-speed data. Some offer truly unlimited high-speed access, while others have a 75 GB cap, 4 GB cap, etc. before speeds are slowed.

📌Important: If your regular plan has a data limit, you could end up with extra charges or super slow speeds (as low as 128 Kbps) once you hit your cap, depending on your plan’s terms.

Keep your domestic plan’s terms in mind when thinking about how much high-speed data you will need in Japan.

Data Amount & Costs📱

While those with an unlimited plan and an IDP shouldn’t have to worry about extra fees, those planning on going with pay-per-use rates should be aware of the costs. $2.05/MB is very expensive for data, especially since you will likely be using more data than usual during your travels.

Here is an estimate of how much data you can expect to use:

• Using Google Maps and sending texts: 500 MB ~ 800 MB/day
• Browsing the internet and using social media: 800 MB ~ 1.5 GB/day
• Watching videos: 1000 MB (1 GB) ~ 3000 MB (3 GB)/day

If you plan to navigate frequently, scroll social media, or watch videos, this will be very expensive.
Here’s how much 1GB of data would cost with AT&T’s pay-per-use rate:

1 GB = 1024 MB
1024 MB × $2.05/MB
Total Cost = $2,100.80

So, 1GB of data would cost over $2,000! 😳 For this reason, we do not recommend traveling with pay-per-use rates.

Additionally, if you’re on AT&T’s 4GB plan, you’ll want to be careful not to go over your data limit (you’ll be charged $10 for each additional 2 GB).

Instead of paying for expensive international roaming plans (like AT&T’s), skip the hassle and go with a local eSIM/SIM!
・You probably won’t need your U.S. number while you’re in Japan.
・You’ll save a ton on roaming fees.
・Sakura Mobile’s 5G unlimited data eSIM gives you full coverage (on the au network).
・Perfect for maps, social media, and streaming.
・No FUP = no throttling, truly unlimited data with no slowdowns.

🛫Staying in Japan for more than 90 days?

If you’re planning a longer stay in Japan—maybe for work, study, or a working holiday—then a voice + data SIM/eSIM with a Japanese phone number might be more convenient.

It’s usually much more economical to cancel or suspend your U.S. phone plan (like AT&T) and switch to a local provider if you’re staying long-term. Check out our Voice + Data plans below!

Want to compare your options? For the best SIM cards for long-term stays in Japan, be sure to check out the following article!
Best SIM Cards for Long-Term Stays in Japan

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Is AT&T Worth it in Japan?

AT&T’s international plans may not be affordable and may not be the best value if you do not already have an unlimited plan. Here is a breakdown of the total costs for the IDP below (click image to enlarge):

Keep in mind you’ll be paying your monthly domestic plan fee (unlimited from $66 to $86) plus the IDP, so this can add up quickly. Even with the cheapest unlimited plan, a 7-day trip will cost you around $150 ($84 IDP costs + $66 unlimited plan) on your monthly bill.

There are numerous providers that sell prepaid eSIM/SIM cards for usage in Japan that are about half the price of AT&T’s plans, with some even offering unlimited data.

See how Sakura Mobile’s unlimited data SIM/eSIM compares below (click to enlarge image):

Sakura Mobile’s 5G truly unlimited eSIM (no daily limit!) is also a great deal at only $46 for 10 days of unlimited data. It’s an excellent option if you use a lot of data and don’t want to be slowed down by any data restrictions.

If your phone isn’t eSIM compatible, we also provide a 4G unlimited travel SIM starting from 4,950 JPY (tax incl.) for 8 days of data. With the current exchange rate, that’s only $35! (*USD/JPY=142.69 as of 4/15/2025)

AT&T’s International Plans are convenient because you can use your phone without taking out and switching the SIM card. However, it should be noted that this convenience also comes at a steep price.

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3. Who Should Use AT&T International Plans?

Taking into account all the above points, these are the types of people to whom we can and cannot recommend AT&T’s International Plans.

Recommended if:

• You want to keep your phone number/line available while traveling. (For work, family, etc.)
• You’re traveling to multiple countries and don’t want to swap SIMs.
• You do not mind the higher costs added to your plan.

NOT recommended if:

• You want to reduce costs as much as possible.
• You don’t plan on making phone calls (You’re planning on using applications such as WhatsApp, etc.)
• You do not want to use the data you have on your monthly plan while overseas.

If you want to save money or are fine with just using data, then buying a prepaid SIM card or eSIM for Japan may be the best option.

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4. Why Choose Sakura Mobile? Affordable & Flexible Data Options

We understand that everyone’s data needs differ, and you have much to plan for your Japan trip. If you want a simple and reliable SIM/eSIM for Japan travel, we recommend Sakura Mobile as the best option.

Best Use Cases:

Even though AT&T’s international plans may sound convenient, they can come with hidden downsides or limits based on your domestic plan. Here’s when Sakura Mobile makes more sense:

• 💰Reduce costs: No need to pay a full month of your domestic plan plus the $12 IDP daily rate. Our unlimited SIM/eSIM is a fraction of the cost.
• 📲Heavy data users: Our 5G unlimited data eSIM and 4G eSIM/SIM card plans mean no $2,000 surprise bills from pay-per-use rates.
• 🧳Travelers who don’t need their U.S. number: By using apps like WhatsApp, Messenger, or LINE, a data-only SIM or eSIM is all you need for short trips.

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5. Maximize Your Data with These Tips

Traveling with limited data? Here are some simple ways to save data and make the most of your connection:

6. Check This Before Your Trip

Is your phone compatible with Japanese frequency bands?

Before heading to Japan, it’s essential to check if your phone is compatible with the country’s frequency bands.

To ensure compatibility with Sakura Mobile, you can check your device against our compatibility list:

• Sakura Mobile physical SIM compatibility
• Sakura Mobile eSIM compatibility

If your device isn’t listed, don’t worry! Our customer support team is here to help. Just reach out with your questions, and we’ll get back to you by the next day.

• 💬Contact Us

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7. Enjoy Your Trip to Japan!

With so many different foods to taste and places to visit during your trip to Japan, your phone not working should be the last thing on your mind.

We recommend getting Sakura Mobile’s Travel SIM/eSIM to be as safe as possible and enjoy your trip to the fullest.

Ready to Stay Connected?🌸

Try Sakura Mobile’s 5G Unlimited Data eSIM!

Sakura Mobile’s truly unlimited 5G eSIM is perfect if you want peace of mind during your Japan trip.

• 🚀 Truly unlimited 5G data – No FUP = no daily limits, no slowdowns, no stress

• 🧠 Worry-free travel – No need to monitor usage or top up data passes

• 🌍 Instant connection – Just pre-order online and scan a QR code to get started

• 🏞️ Perfect for travelers – Navigate, share photos, and stream without limits

• 📸 Focus on the fun – Spend less time managing data and more time making memories

Stay connected effortlessly, enjoy Japan to the fullest, and focus on making memories, not managing data. Enjoy your trip to Japan without stressing about data passes!

Not a heavy-data user? Check out our 4G Travel SIM/eSIM:

4G Unlimited eSIM:

• 4G high-speed data: 3 GB/day
• Unlimited low-speed data

4G Travel Physical SIM

• Up to 2GB/day of high-speed data
• Unlimited low-speed data

Staying in Japan for more than 90 days?

Using your AT&T plan in Japan is not recommended for extended stays due to their terms, which state that primary usage must be in the US. Your service may suddenly be terminated for excessive roaming. If you’re staying in Japan for a while, check out our long-term plans below!

Thank you for reading, and have a great trip!

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