The most common mistake when buying a travel eSIM is not picking the wrong provider; it is picking the wrong size. Too small and you are topping up at the worst moment; too large and you have paid for gigabytes you never used. The good news is that data use is predictable once you know what each activity costs.
What one hour of each activity uses
These are typical figures for a modern phone with default settings:
- Navigation (Google Maps, Apple Maps): 5 to 10 MB per hour of active turn-by-turn. Downloading an offline map of a city beforehand reduces this to almost nothing.
- Messaging (WhatsApp, iMessage, Telegram): text is negligible; photos cost 1 to 3 MB each, short videos 10 to 50 MB each.
- Email and web browsing: 30 to 60 MB per hour.
- Social media scrolling with autoplaying video: 150 to 300 MB per hour. This is the quiet budget killer.
- Music streaming: 50 to 150 MB per hour depending on quality.
- Video calls: 300 to 700 MB per hour for one-to-one calls; more for group calls.
- Video streaming: 500 MB to 1 GB per hour in standard definition, 1.5 to 3 GB per hour in HD.
- Photo backup to the cloud: 3 to 5 MB per photo; a day of 100 photos is 300 to 500 MB, and 4K video is far more. Set backups to Wi-Fi only.
Three traveller profiles
- Light: maps, messaging, a few photos, no video. Around 300 MB per day. A week is 2 to 3 GB; two weeks, 5 GB.
- Typical: the above plus social media, music, the occasional video call. Around 750 MB to 1 GB per day. A week is 5 to 7 GB; two weeks, 10 to 15 GB.
- Heavy: streaming in the evening, daily video calls, tethering a laptop. 2 GB per day or more. A week is 15 GB; two weeks, 30 GB, or a daily-allowance plan.
Fixed volume or daily allowance?
Plans come in two shapes. A fixed volume (say 10 GB valid for 30 days) suits uneven use: heavy on travel days, light on the beach. A daily allowance (say 1 GB per day, resetting every day) suits consistent use and streaming, and often works out cheaper for heavy users, but unused daily data does not carry over.
"Unlimited" plans are a third shape with their own rules; we explain them in what 'unlimited' really means on an eSIM.
A simple formula
Daily estimate from your profile × number of days × 1.3. The 30 percent margin covers the day your hotel Wi-Fi fails and the evening you watch a film on the phone. If the result sits between two plan sizes, take the larger one: the price per gigabyte almost always drops with size, so the step up costs less than it seems.
Cut your usage without noticing
- Download offline maps for every city on the itinerary.
- Set photo and video backup to Wi-Fi only.
- Turn off autoplay in social apps.
- Download playlists and shows before you leave.
- Enable "Low Data Mode" (iPhone) or "Data Saver" (Android) on the eSIM line.
When you know your size, compare plans at that size by price per GB on esimlist.com, and let the filters hide everything that is too small or expires too soon.