Know your charger's real speed.
Wattio tests how fast each charger and cable actually charges — in watts — tells you when to unplug, and keeps your battery healthy. All on your iPhone. No data collected.
Download on the App StoreOne app for everything charging
iOS doesn't tell you how fast you're charging or whether a cable is worn. Wattio does — and turns it into clear, useful advice.
Charger speed test
Measure the real effective power (watts) of any charger, cable or power bank. Find your fastest — and spot a worn cable.
Smart charging coach
Tells you exactly what to do now: unplug at 80% to protect the battery, or top up before a trip.
Charge alarm
A sound and notification the moment you hit your target percentage. Never overcharge overnight again.
Battery health log
Track your maximum capacity over time on a clean chart and watch how your battery ages.
Energy Flow screen
A mesmerizing ambient nightstand view while you charge — live power, time to full, and a living energy field.
Widgets & Live Activity
Battery, watts and time-to-full on your Home Screen, Lock Screen and Dynamic Island.
Knows your iPhone
Built-in spec database: your exact cable (USB-C / Lightning), MagSafe limit and the adapter you need for full speed.
Syncs with iCloud
Your tests and history follow you across devices and survive a reinstall — through your own private iCloud.
Private by design
Everything runs on-device. No account, no ads, no tracking, no data collected.
How the watt test works
iOS gives apps no direct charging-wattage API. So Wattio measures the charge-curve slope — how fast the percentage rises over time — and multiplies it by your model's exact battery energy:
watts ≈ (%/min × 0.6) × battery Wh
This is the effective power reaching the battery — always a little below the charger's printed rating (there are losses, and charging slows above 80%), so a "20 W" adapter reads around 14–16 W. Longer tests are more accurate. Honest estimates, clearly labelled — never fake precision.