Core answer: Streaming is the data budget's main course: 1080p video ≈ 3 GB/hour, 4K ≈ 7–20 GB/hour, music ≈ 150 MB/hour, video calls ≈ 1 GB/hour, maps ≈ 5 MB/hour. A 30 GB/month plan covers ~10 h of 1080p streaming OR 200 h of music — know your mix before choosing a plan. "Unlimited" plans throttle after a cap (commonly 20–40 GB at full speed).
What activities actually cost
| Activity | Data per hour | 1 GB lasts |
|---|---|---|
| 4K video | 7–20 GB | 3–8 min |
| 1080p video | ~3 GB | 20 min |
| 720p video | ~1.2 GB | 50 min |
| Video call (HD) | 0.8–1.5 GB | ~50 min |
| Music (320 kbps) | ~150 MB | ~7 h |
| Podcast/audiobook | ~60 MB | ~17 h |
| Web browsing | ~100 MB | ~10 h |
| Maps/navigation | ~5 MB | days |
| Online gaming (play) | 50–200 MB | 5–20 h |
| Game download | 10–100+ GB one-time | — |
Worked examples
Example 1 — The commuter budget. Daily: 40 min 1080p (2 GB) + 1 h music (150 MB) + browsing (100 MB) ≈ 2.3 GB/day × 22 workdays ≈ 50 GB/month — the 30 GB plan fails; either drop to 720p offline downloads on Wi-Fi (saves ~90%) or upgrade.
Example 2 — Hotspot trap. Laptop tethered for "just email" auto-downloads a 5 GB OS update over the phone's 20 GB plan. Set connections as metered on Windows/macOS before tethering.
Example 3 — Kid's tablet. Autoplaying YouTube Kids at 1080p for 2 h/day = 180 GB/month — more than most family plans. Lock quality to 480p (0.5 GB/h) in the app settings.
Example 4 — Overseas roaming. ¥25/day roaming passes feel cheap until a cloud photo backup (8 GB) fires abroad: either the pass caps and throttles, or pay-per-MB bills hit hundreds. Disable background sync before boarding.
Common mistakes and myths
- "Unlimited means unlimited" — fair-use caps throttle to 1–3 Mbps after 20–40 GB; fine for chat, dead for video.
- Blaming the carrier for background drain — photo sync, app auto-updates, and cloud backups are the silent majority of "mystery" usage; the OS data-usage screen names the culprit per app.
- Wi-Fi assist betrayal — "Wi-Fi Assist/智能切换" silently falls back to cellular on weak Wi-Fi; the 2-hour movie you watched "on home Wi-Fi" may have billed 6 GB.
- Counting only downloads — video calls and cloud backup UPLOAD heavily; live streaming 1080p uploads 3–5 Mbps ≈ 2 GB/h.
- Thinking quality settings persist — apps reset quality on updates or per-network; verify "data saver" after every app update.