Fixed data or unlimited eSIM: how to choose
Most destinations offer two kinds of plan. A fixed plan gives you a set amount of data, say 5 GB, to use any way you like until it runs out or the days end. An unlimited plan lets you use data every day, with a daily high-speed allowance printed on the plan, after which speed drops. The simplest way to think about it: fixed caps the trip, unlimited caps each day.
How each plan behaves
| Fixed data | Unlimited, with daily cap | |
|---|---|---|
| What runs out | The total GB | The day's high-speed allowance |
| After the limit | No data until you top up | Slower speed until the next day |
| Uneven days | Fine: spend more one day, less the next | A heavy day hits the cap; a light day's leftover is lost |
| Best for | Predictable, light to medium use | Heavy daily use, hotspot, not wanting to count |
On most unlimited plans the cap is a few GB a day, then about 1 Mbps. The exact figure varies by destination and plan, so read the plan line before you buy. On the Japan page, for example, each unlimited plan shows its own cap.
Do the maths for your trip
Our planner uses three daily rates: 0.2 GB for maps and messaging, 0.5 GB for socials and photos, 1.3 GB for streaming or hotspot. Multiply by your days and add 15% headroom.
| Trip | Maps and messaging | Socials and photos | Streaming or hotspot |
|---|---|---|---|
| 7 days | 1.4 GB → about 1.6 GB | 3.5 GB → about 4 GB | 9.1 GB → about 10.5 GB |
| 14 days | 2.8 GB → about 3.2 GB | 7 GB → about 8 GB | 18.2 GB → about 21 GB |
| 30 days | 6 GB → about 6.9 GB | 15 GB → about 17.3 GB | 39 GB → about 45 GB |
If a fixed plan in the size you need is on the page, that is usually the simpler buy. When your total climbs into the streaming column, compare it against the unlimited plan for the same number of days.
Check your heaviest day, not your average
A fixed plan only cares about the total. An unlimited plan cares about each day. Two trips with the same total can behave very differently:
- Steady use. 0.5 GB every day for 14 days is 7 GB. That is far under a typical daily cap, so unlimited gives you nothing a fixed plan wouldn't.
- Spiky use. Light days plus two days of laptop work over hotspot. A fixed plan absorbs the spike from the pool. An unlimited plan slows down on those two days once you pass the cap.
So before you choose unlimited for "safety", ask whether your heaviest day would fit under the cap printed on the plan. If you're not sure what a heavy day looks like for you, check your usage on a normal day at home.
When unlimited is the better choice
- You stream or video-call most days, so your total sits in the right-hand column.
- You share your connection with a laptop or a travel partner every day. See using a travel eSIM as a hotspot for the caveats.
- You don't want to think about a meter at all, and the slower speed after the cap is acceptable for evenings.
When fixed is the better choice
- Your use is maps, messaging, socials and photos backed up on Wi-Fi.
- Your days are uneven, with a few heavy ones.
- You want a clear limit, then a deliberate top-up if you need more.
Running out: what each plan does
On a fixed plan, when the data runs out, data stops. You can top up from your account page while the plan is valid. It's a deliberate tap and nothing renews on its own. On an unlimited plan, data continues at the lower speed until the next day's allowance. Neither plan charges you anything extra without you choosing it. If an unlimited plan turns slow in the afternoon, the cap is the likely cause; slow travel eSIM data shows how to tell.
A Japan example
Ten days in Tokyo and Kyoto, socials and photos, with photo backup on hotel Wi-Fi: 5 GB, about 5.8 GB with headroom. A fixed plan of that size fits. The same ten days with streaming every evening: 13 GB, about 15 GB with headroom. At that level, compare against the unlimited plan for ten days. The Japan guide shows the plans for your trip length, and how much data you need explains the rates. If you're still deciding how to get connected in Japan at all, read Japan tourist SIM or eSIM.
Questions
Is an unlimited eSIM really unlimited?
You can keep using data all day, but each day has a high-speed allowance. After it, speed drops for the rest of that day. The exact cap is printed on the plan line.
Does unused unlimited allowance roll over to the next day?
No. The high-speed allowance resets each day. A fixed plan is different: unused data stays in the pool until the plan ends.
Is the slower speed after the cap usable?
On most plans it is about 1 Mbps. That is fine for messaging, maps and email, and slow for video, photo uploads or a laptop.
What if I hit the daily cap every day?
Then your daily use is above the cap, and a fixed plan sized at the streaming rate may suit you better. Moving video, uploads and updates onto Wi-Fi also keeps you under it.