eSIM data usage calculator: how much data do you actually need?
Most people either buy way more data than they'll use or run out three days into a two-week trip. Here's what maps, streaming, and video calls actually cost in MB per hour, and how that adds up over a real itinerary.
Why "how much data do I need" is the wrong first question
Every eSIM checkout page makes you pick a plan size before you've really thought about what you'll do with your phone once you land. So people guess. Some overshoot out of fear of going dark on day four, some lowball it to save a few euros, and both groups are wrong for the same reason — data use was never one number to begin with. It's five or six very different habits stacked on top of each other, and most of them barely move the needle.
Walking around a new city all day with maps open, firing off the occasional Instagram story, texting the group chat back home — that costs almost nothing. Meanwhile a single two-hour video call, the kind where the hotel Wi-Fi drops out halfway through and your phone quietly switches to cellular without telling you, can burn through more data than that entire day of sightseeing. Buying a bigger plan doesn't fix that. Knowing which of your habits are actually expensive does.
What common activities actually cost
| Activity | Approximate data use |
|---|---|
| GPS navigation (Google/Apple Maps, live) | 5–10 MB per hour |
| Offline map download (one city or region) | 100–300 MB, once |
| Messaging (WhatsApp, iMessage, texts) | Under 5 MB per hour |
| Browsing / email | 20–60 MB per hour |
| Social media scrolling (Instagram, TikTok) | 300–700 MB per hour |
| Music streaming (Spotify, standard quality) | 50–150 MB per hour |
| Video call (FaceTime, Zoom, WhatsApp video) | 250 MB–1 GB per hour |
| Video streaming, SD (480p) | ~300 MB per hour |
| Video streaming, HD (720p–1080p) | 700 MB–1.5 GB per hour |
| Video streaming, 4K | 3 GB+ per hour |
Notice the gap between navigation and video streaming — three orders of magnitude apart. Maps are cheap because they're mostly cached tiles and tiny location updates. Video is expensive because every frame is new data. If you're trying to stretch a small plan, streaming is the first thing to cut, not maps.
By travel style
Recommended data by trip length
These assume a mix of the above — mostly maps and messaging, some social media, occasional video calls, and streaming saved for Wi-Fi where possible. Adjust up if streaming or video calls are a daily habit rather than an occasional one.
| Trip length | Recommended data |
|---|---|
| Weekend trip (2–3 days) | 2–3 GB |
| 1 week | 5–8 GB |
| 2 weeks | 10–15 GB |
| 1 month | 20–30 GB |
| Remote work / digital nomad, ongoing | 30–50 GB per month |
Add roughly 20% on top of your honest estimate. Unused data on most plans just expires quietly, but running out on your last day in a country with no Wi-Fi at the gate is the more expensive mistake. If you're between two plan sizes, size up.
What actually happens if you run out
Travel eSIMs don't usually charge you for going over — they just stop working. The connection quietly drops to nothing rather than switching to a metered overage, which is a relief the first time it happens and mildly infuriating the second time you're trying to pull up a boarding pass with no signal.
The fix is almost always a top-up: most providers let you add more data to the same eSIM profile in a couple of taps, and it's usually active again within minutes. If the plan has fully expired rather than just running dry, you'll need a fresh eSIM instead — worth checking your remaining balance a day or two before you expect to need it, rather than discovering the gap mid-taxi-ride.