Tools · eSIM data calculator

How much data will you need?

Tell us where you are going, for how long, and how you use your phone away from Wi-Fi. We will work out the gigabytes, then find the cheapest plan from four eSIM providers that actually covers it, including the catches on the unlimited ones.

Japan · 1 month · Normal phone use

28 GB to plan for.

About 23 GB over 1 month, plus a fifth on top so you do not run out. Your busiest day is about 800 MB. Cheapest that covers it: Nomad, 50 GB, 30 days, for £26.29.

Your phoneMaps, messages, an hour or two of browsing and social media, and some music: about 400 MB a day.
12 GB
Video calls1 hour a week. Zoom gives 1.2 Mbps each way for a one-to-one call in 720p, which is about 1.1 GB an hour.
4.7 GB
Streaming2 hours a week. Netflix says standard definition uses up to 0.7 GB an hour and HD up to 3 GB. We count 0.7; on a phone's automatic setting it can be nearer 0.25.
6 GB

The cheapest way to get 28 GB in Japan, provider by provider

  1. Nomad50 GB, 30 days
    Cheapest£26.29
    See Nomad's Japan plans
  2. Saily2 × 20 GB, 30 days each
    £37.54
    See Saily's Japan plans
  3. AiraloUnlimited, 30 days
    £51.83
    See Airalo's Japan plans
  4. HolaflyUnlimited, 30 days
    £55.51

    Holafly says it may slow your connection for up to a day to manage network traffic, without saying at what point.

    See Holafly's Japan plans
  5. Saily2 × Unlimited, 15 days each
    £73.59
    See Saily's Japan plans
  6. Nomad2 × Unlimited, 21 days each
    £73.61
    See Nomad's Japan plans

Prices were read in US dollars and converted at today's rate. The providers may charge a slightly different amount in your currency.

How it counts. Only what you use away from Wi-Fi. Calls, laptop work and streaming are spread evenly over each week; your phone use is the same every day. The busiest day is a working day on the laptop: your phone use, a fifth of the week's calls, a seventh of the week's streaming and a full day of laptop work. Your phone use levels are our own estimates, built from published figures for maps, browsing and social media. A fifth is added on top. Each provider's cheapest option is shown twice at most: its best fixed-GB plan, and its best unlimited plan, bought as many times as the stay needs.

Where the figures come from. Zoom, bandwidth requirements · Netflix, how to control data use. Laptop work over a hotspot is our own estimate.

Where the prices come from. Each provider's own Japan page, read on 8 October 2026, in US dollars. Prices change often and sales come and go, so check the provider's page before you buy. Plans whose price looked out of line with the rest of the page when we read it were left out. Airalo's fixed-GB prices come from Airalo's own plan data, where we could read it: its country pages open on the unlimited plans. Speed limits and hotspot rules: Airalo, fair use on unlimited plans · Saily, fair usage policy · Holafly, plan details on each country page · Nomad, unlimited plan details.

What it does not cover. Calls and texts to local numbers, local SIM cards (which need a shop visit and often a passport), and roaming on your home plan. Saily says its unlimited plans allow hotspot use but bans "excessive" tethering; Nomad's help pages and plan details give different slow-down speeds. For Saily in the UAE, Mexico and South Africa we assume 3 GB a day at full speed, as a comparison site lists; Saily's own pages do not say. Plans that cover your use without a catch come first, then by price. Some links may earn us a commission; that never changes the order.

Exchange rates from 20 October 2026.