Unlimited data sounds like the safe choice for Japan. For most first-timers it is the expensive one. The honest question is not "unlimited or not" but "how many gigabytes a day do I actually use" - and once you count it activity by activity, the break-even lands near 1.5 GB a day. Below that, a capped plan is cheaper and never throttles. Above it, unlimited wins outright.
Do you need unlimited data in Japan?
Probably not. A normal sightseeing day in Japan - maps, transit apps, messaging, some scrolling, a few uploads - lands around 1 to 2 GB. A light day stays under 0.7 GB. Hotel and konbini Wi-Fi absorb the evening. Unlimited only pays for itself past roughly 1.5 GB a day, every day, which in practice means streaming on trains or running a hotspot for someone else.
The cheapest way to check is your own phone. Open Settings and read last month's cellular data, then divide by thirty. That is your real baseline, with your habits and your apps, not a number from a review site. In Japan you will use slightly more navigation and slightly less streaming, because you will be walking. If that daily figure is under 1.5 GB, buy a capped plan and stop reading price pages.
What actually uses your data, activity by activity
Four things move the needle: navigation, social, video and tethering. Only the last two are big. Below we break each one down, and we are explicit about which figures are published by the service and which are our own estimates. Nobody publishes a per-app data figure for Japan, so anyone quoting one to two decimal places is guessing. We would rather show the method.
Navigation is the fear that sells unlimited plans, and it is the smallest line on the bill. Map tiles are vector data measured in hundreds of kilobytes, not megabytes. Our estimate is roughly 5-20 MB per hour of active navigation, so even three hours of walking directions a day stays under 100 MB. That is an estimate derived from tile sizes, not a published figure: Google publishes no data-per-hour number for Maps anywhere in its help pages.
Offline maps help less than the standard advice suggests. Google's own support page is blunt about the limits: when you are offline, transit, cycling and walking directions are unavailable, and driving offline gives you no traffic and no alternate routes. In Tokyo you navigate almost entirely by train and on foot - exactly the two modes offline maps do not cover. Download offline areas for a rental-car day in the countryside; do not count on them in a city.
Messaging is free in practice. LINE, WhatsApp and iMessage text traffic is a few megabytes a day, and even a long voice call is tens of megabytes. What costs money is the video inside social apps. Reels and TikTok-style feeds run at roughly 1.5-2.5 Mbps on mobile, which works out near 0.5-1 GB per hour of scrolling - our derivation from mobile video bitrates, since neither Meta nor ByteDance publishes a figure. Twenty minutes of scrolling on the train each way is a third of a gigabyte.
Uploads are the quiet one. A modern phone photo is 3-5 MB, so backing up a hundred shrine shots over cellular is roughly 0.4 GB. A thirty-second 4K clip to the family chat is 100-150 MB on its own. If iCloud Photos or Google Photos is set to back up over mobile data, turn it off before you fly. That single toggle is worth more than any plan upgrade you are considering.
Streaming is the line that breaks the budget, and here the numbers are actually published. Netflix documents up to 0.3 GB per hour on Low, 0.7 GB on Medium, 1 GB for standard definition on High, 3 GB for HD and 7 GB per hour for 4K. On mobile, its Automatic setting runs about four hours per gigabyte, while Maximum Data can burn a gigabyte every twenty minutes. YouTube publishes no equivalent table; from streaming bitrates we estimate roughly 0.5 GB per hour at 480p, 0.9 GB at 720p and 1.5-2 GB at 1080p.
Tethering is the real reason people buy unlimited, and it is the only activity that reliably doubles your daily figure. A laptop does not behave like a phone: it syncs cloud drives, pulls email with full attachments, downloads OS updates and runs video calls at desktop quality. A 1080p video call moves roughly 0.7-0.9 GB per hour in each direction, derived from published video-call bandwidth requirements. One working day on a hotspot lands at 2-5 GB, which clears every break-even in this article on its own.
Three traveler profiles and what they really use per day
Add the activities up and travelers fall into three bands: light users at 0.3-0.7 GB a day, normal sightseers at 1-2 GB, and hotspot or streaming users at 3-8 GB. These are our estimates, built from the per-activity figures above rather than from survey data. But they are the right shape: the first two bands sit under the break-even, and the third sits far above it.
Light: maps, transit apps, LINE and WhatsApp, a little browsing, photos backed up on hotel Wi-Fi at night. Call it 0.5 GB a day, so 3-4 GB over a week and about 7 GB over two. A 10 GB plan covers a fortnight with room to spare, and you will land back home with data left unused.
Normal: everything above, plus social scrolling on trains, a couple of YouTube videos, translation, restaurant research, and photo uploads that do not always wait for Wi-Fi. Call it 1.5 GB a day: roughly 10 GB in a week, 21 GB in two. This band sits almost exactly on the break-even, which is why the honest answer for most people is close rather than obvious.
Hotspot and heavy: you share the connection with a partner's phone or a laptop, take work calls, stream on the Shinkansen, or upload video every evening. Call it 4 GB a day and up: 28 GB in a week, 56 GB in two. No capped Japan plan on sale covers that at a sane price. This is the profile unlimited actually exists for.
The break-even: how many GB before unlimited wins
About 1.5 GB a day. Priced against Ubigi's own capped ladder, unlimited starts winning past roughly 10 GB on a seven-day trip, 25 GB on a fortnight and 50 GB on a month. Below those numbers you pay more for unlimited and get less full-speed data than a capped plan gives you. Above them, unlimited is both cheaper and simpler. All prices here were checked on 1 September 2026.
The math is cleanest inside one provider's own ladder, so the comparison is like for like. Ubigi sells 10 GB for $16.50, 25 GB for $32 and 50 GB for $55, all with 30-day validity and no throttling. Its unlimited plans cost $25 for 8 days, $39 for 15 days and $65 for 30. On a one-week trip, the $8.50 gap between the 10 GB plan and the 8-day unlimited is what buys you everything above 10 GB. That is the whole decision.
| Trip length | Best capped plan | Unlimited alternative | Break-even / fair use |
|---|---|---|---|
| 7 days | Ubigi 10 GB / 30 days - $16.50 | Ubigi unlimited 8 days - $25 (5 GB/day, then 2 Mbps) | About 10 GB, or 1.4 GB/day |
| 14 days | Ubigi 25 GB / 30 days - $32 | Ubigi unlimited 15 days - $39 (30 GB, then 2 Mbps) | About 25 GB, or 1.8 GB/day |
| 30 days | Ubigi 50 GB / 30 days - $55 | Ubigi unlimited 30 days - $65 (60 GB, then 2 Mbps) | About 50 GB, or 1.7 GB/day |
| Airalo, any length | No capped Japan package listed on its country page | $27 / 7 days, $48 / 15 days, $69 / 30 days | 3 GB/day, then 1 Mbps. No tethering limit |
| Saily, any length | Saily 20 GB / 30 days - $24.99 | Saily unlimited 15 days - $48.99 | 5 GB/day, then 1 Mbps. Hotspot allowed |
| Holafly, any length | No capped option sold | $27.50 / 7 days, $50.50 / 15 days, $73.90 / 30 days | No published GB threshold. Hotspot 1 GB/day |
One detail that softens the risk of guessing low: every provider here lets you top up in the app in a couple of taps. Underbuying costs you a few dollars and two minutes of your evening; overbuying costs you the difference for good. For scale, $25 is about 3,950 yen at 158 yen to the dollar - roughly two konbini lunches and a coffee.
Fair-use policies: what "unlimited" actually means
No Japan eSIM is truly unlimited. Every plan has a fair-use threshold after which speed drops, and the useful question is where it sits and whether the provider publishes it at all. Ubigi and Airalo publish exact numbers. Saily publishes a daily figure. Holafly publishes none. A provider that hides its threshold is telling you something. We checked all four on 1 September 2026.
Ubigi publishes a different threshold on every plan page, and the differences are large. Its 8-day unlimited gives 5 GB a day at full speed, then 2 Mbps, with the allowance resetting every 24 hours from your activation time - up to 40 GB of full-speed data across the plan. Its 15-day plan gives 30 GB in total before dropping to 2 Mbps, and the 30-day plan gives 60 GB. Data sharing is allowed on all of them, and hotspot traffic counts against the same pool.
Watch which Ubigi page you land on. On 1 September 2026 two unlimited Japan pages were live at the same $25 price: a 7-day plan throttled to 1 Mbps after 15,360 MB in total, and an 8-day plan giving 5 GB a day at full speed and 2 Mbps after. Same money, very different plan - 15 GB of full-speed data against a possible 40 GB. Read the fair-use line on the page you are actually buying from.
Airalo publishes one policy covering all its unlimited plans: pass 3 GB in a day and speed drops to 1 Mbps for the rest of that day, with the allowance resetting every 24 hours counted from the moment you activated the eSIM. Its Japan page listed unlimited packages only when we checked - $27 for 7 days, $48 for 15 and $69 for 30. Saily's Japan unlimited gives 5 GB a day before dropping to 1 Mbps, and was priced at $48.99 for 15 days.
Holafly is the outlier, and not in a good way. Its Japan page sells 7 days at $27.50, 15 at $50.50 and 30 days at $73.90 - the most expensive here - while publishing no gigabyte threshold at all. The terms say only that fair-use throttling is applied temporarily, for no more than one day at a time. You cannot plan a trip around a policy with no number in it, and at that price you should not have to.
Hotspot and tethering: the real reason to buy unlimited
If you will tether a laptop or share with a travel partner, the decision flips - but check the sharing rules before you check the price. Airalo states there is no limit on tethering or the number of connected devices. Ubigi allows data sharing, counted against the plan's own pool. Saily advertises unrestricted hotspot sharing. Holafly caps sharing at 1 GB per day, which makes its unlimited badge close to meaningless for a laptop.
For a couple, run the numbers both ways. Two Ubigi 10 GB plans cost $33 together and give you a spare line if one phone or one eSIM misbehaves - cheaper than a single $39 unlimited fortnight and far cheaper than $65 for a month. One unlimited line plus hotspot only wins when one of you is genuinely heavy and the other barely touches data. For laptop work, prefer a high total cap over a tight daily one: a video call plus a cloud sync can eat a 3 GB daily allowance before lunch.
When to install your eSIM, and when the clock starts
This trips people up on short unlimited plans, where one wasted day is a seventh of what you paid. Ubigi is unambiguous: the plan activates automatically on arrival in a covered destination, and the validity period starts from that moment. Airalo is not: its help pages say validity starts either when you install the eSIM or when you first connect to a supported network, depending on the package.
The practical rule: install and configure the eSIM at home on Wi-Fi, days before you fly, but leave data roaming off on that line. Installing is the fiddly part, and the Narita arrivals hall is a bad place to do it. Then read the package's own validity policy before you buy, because Airalo explicitly says the trigger varies by package, and switch the line on only after you land. Ubigi's plans also expire if you have not activated them within six months of purchase.
Our picks per profile
Light user, one or two weeks: a 10 GB capped plan around $16.50, and you will not finish it. Normal sightseer on a fortnight: 25 GB for $32, or the $39 unlimited fortnight if you would rather not think about it again. Hotspot, remote work or daily streaming: an unlimited plan with a generous published daily threshold. For which provider to buy from - coverage, speeds, setup - read our Airalo vs Ubigi comparison; this page only answers how many gigabytes. And landing without data is worse than landing with too little: your Visit Japan Web QR code needs a connection if you have not screenshotted it, and our Japan daily budget guide shows where data sits against everything else you will spend.
Frequently asked questions
Do "unlimited" Japan eSIMs really throttle?
Yes, all of them. Airalo drops you to 1 Mbps once you pass 3 GB in a single day, with the allowance resetting 24 hours after activation. Ubigi's 8-day plan gives 5 GB a day at full speed then 2 Mbps; its 15-day plan gives 30 GB in total and its 30-day plan 60 GB, both then 2 Mbps. Saily gives 5 GB a day, then 1 Mbps. Holafly publishes no gigabyte threshold at all, only that throttling is temporary and lasts no more than one day at a time. "Unlimited" means you keep a usable connection, not unlimited full speed.
When should I install the eSIM? Does the countdown start at install or first connection?
It depends on the provider, and on a short unlimited plan the difference is worth a day of what you paid. Ubigi states that the plan activates automatically on arrival in a covered destination, with the validity period starting from that moment, so installing it at home weeks ahead costs you nothing. Airalo's help pages say validity begins either when you install the eSIM or when you connect to a supported network, depending on the package, and tell you to check that package's validity policy before buying. The safe routine either way: install at home on Wi-Fi, leave data roaming off on the travel line, switch it on after you land.
Which plans cap or block hotspot use?
Holafly caps sharing at 1 GB per day, which rules it out for a laptop. Airalo's fair-use policy states there is no limit on tethering or on the number of connected devices, though everything you share still counts toward the 3 GB daily threshold. Ubigi allows data sharing and counts hotspot traffic against the plan's own pool. Saily advertises unrestricted hotspot sharing. If tethering is the point of the plan, pick a high total cap rather than a tight daily one.
How much data does Google Maps use, and do offline maps fix it?
Less than people fear. Google publishes no data-per-hour figure for Maps, so treat any precise number you read online as a guess; our own estimate, derived from map tile sizes, is roughly 5-20 MB per hour of active navigation. Offline maps help less than the usual advice suggests: Google's support pages state that transit, cycling and walking directions are unavailable offline, and that driving offline gives you no traffic and no alternate routes. In a Japanese city you navigate by train and on foot, so download offline areas for a rental-car day in the countryside, not for Tokyo.
Is unlimited worth it for a 2-week trip?
Only above about 25 GB, which is roughly 1.8 GB a day. Ubigi's 25 GB plan is $32 with no throttling at all; its 15-day unlimited is $39 with 30 GB at full speed before dropping to 2 Mbps. Normal sightseeing lands near 21 GB over two weeks, just under the line, so most travelers should take the capped plan and top up in the app if they guessed low. Tether a laptop for even two working days and you cross the line comfortably.
Couple traveling: one unlimited plan or two capped plans?
Two capped plans, usually. Two Ubigi 10 GB plans cost $33 together, less than one $39 unlimited fortnight, and give you a second line if a phone or an eSIM misbehaves - a real risk when neither of you has a Japanese SIM to fall back on. Go with one unlimited line plus hotspot only when one of you is a genuinely heavy user and the other barely touches mobile data.
Which networks do these eSIMs use in Japan?
Ubigi's plan pages list KDDI and NTT Docomo, a dual-network setup that helps outside the big cities. Saily's Japan page lists KDDI and SoftBank. Airalo's Japan page shows SoftBank plus one other network it does not name, so we will not guess which. Holafly's Japan page did not state its networks when we checked on 1 September 2026. For rural and mountain routes, a Docomo-based option tends to hold signal best.
