Everyone tells you to buy unlimited to be safe. Then you land in Tokyo, use 800MB on day one, and realize your 10GB plan would have lasted the whole trip. Or you buy 3GB for two weeks in Thailand and run out on day four because you forgot about offline maps eating data while navigating continuously. Here's how to calculate what you actually need — not the guess, the math.
What Each Activity Actually Consumes
| Activity | Data per hour | Per day typical |
|---|---|---|
| Google Maps navigation (active) | 5–15 MB per hour | 30–80 MB navigating 4–6 hours |
| Google Maps casual checking | 2–5 MB per lookup | 20–50 MB |
| WhatsApp messaging + photos | 5–20 MB per hour | 20–60 MB |
| WhatsApp voice call | ~1 MB per minute | 30 MB per 30-min call |
| WhatsApp video call | ~5–8 MB per minute | 150 MB per 30-min call |
| Instagram scrolling feed | 30–80 MB per hour | 30–60 MB casual |
| Instagram Story upload | 3–10 MB each | Variable |
| Google Translate camera mode | 5–15 MB per hour | 10–30 MB |
| Uber / Grab booking rides | 1–3 MB per booking | 5–20 MB |
| Offline Maps download (one city) | 50–300 MB one-time | Do this on hotel WiFi |
The Calculation by Trip Type
Light traveler (city-focused, hotel WiFi at night):
Maps 40 MB/day, WhatsApp 40 MB/day, Instagram casual 40 MB/day, buffer 500 MB, 14 days total: approximately 2.2 GB. Buy a 3GB plan.
Standard traveler (cities and towns, daily navigation):
Maps 70 MB/day, WhatsApp including video calls 100 MB/day, social media 80 MB/day, buffer 1 GB, 14 days total: approximately 4.5 GB. Buy a 5GB plan.
Heavy traveler (road trip, constant navigation, daily uploads):
Maps in active navigation 200 MB/day, WhatsApp and social 150 MB/day, uploads and stories 200 MB/day, 14 days total: approximately 7.7 GB. Buy a 10GB plan.
When unlimited actually makes sense: Remote work with video calls, hotspot for laptop, streaming in accommodation with no WiFi, or group travel sharing data via hotspot. For typical tourist use, a correctly sized 5–10GB fixed plan is more cost-effective and has more predictable speed than a throttled unlimited plan.
Three Situations Where People Get This Wrong
Situation 1: Offline map download counted wrong
A traveler downloads offline Google Maps while on their travel eSIM data instead of hotel WiFi. One offline map download for a major prefecture: 200–400 MB, gone in one session. Rule: always download offline maps on WiFi, not mobile data.
Situation 2: Forgot WhatsApp video calls stack up
A traveler budgets 3GB for 10 days in Europe. Daily WhatsApp video calls home (30 min each) consume 150 MB per call times 10 days equals 1.5 GB on calls alone. Remaining 1.5 GB for everything else: very tight. Factor in call frequency before choosing plan size.
Situation 3: Hotel WiFi was unusable
Hotel WiFi in Vietnam, India, and parts of Southeast Asia is often too slow for video calls. When it fails, travelers use mobile data for everything. Add 1–2 GB buffer if your hotels are in regions where WiFi quality is unpredictable.
Quick Plan Selector
| Trip length | Light use | Standard | Heavy / road trip |
|---|---|---|---|
| 7 days | 1 GB | 3 GB | 5 GB |
| 14 days | 3 GB | 5 GB | 10 GB |
| 21 days | 5 GB | 10 GB | 20 GB |
| 30 days | 5–10 GB | 10–15 GB | 20 GB+ |
FAQ
Is 5GB enough for two weeks in Japan?
For a standard traveler with daily navigation, WhatsApp, and Instagram but no streaming: yes, 5GB covers a standard two-week Japan circuit with room to spare. For a road trip or heavy uploads: move to 10GB. For city-only travel staying in good WiFi hotels: 3GB is sufficient.
Should I download offline maps before or after arriving?
Always before arriving, and always on WiFi — not mobile data. Offline Google Maps for a major city or prefecture can consume 200–500 MB per download. Do this at home or in your hotel on their WiFi.
When does unlimited actually make sense?
When you're doing remote work with video calls, hotspotting for a laptop, or sharing data with multiple devices. For typical tourist use — navigation, messaging, social media — a correctly sized 5–10GB fixed plan is more cost-effective and has more predictable speed than a throttled unlimited plan.
Based on the standard traveler calculation for 14 days: Japan eSIM 5GB · Thailand eSIM 5GB · Europe eSIM 10GB · Australia eSIM 10GB