Watt Charging Speed

iPhone and iPad don't let apps read the charging power from the hardware. Watt works out the charging speed from how quickly your battery percentage rises, combined with your device's battery capacity. That means:

• The figure is an estimate of the watts reaching the battery. That is less than the charger's rated output: a 20 W charger usually reads below 20 W, and that is expected

• iOS reports the battery level in steps, so the first reading can take up to about 10% of charging. After that, the figure follows your charge

• The longer a session runs, the steadier the estimate

• If Watt doesn't know your device's battery capacity, it says so and uses a typical value

WHAT YOU SEE

• A watt estimate while you charge

• Color-coded speed labels: Fast Charging, Charging, Slow Charging and Trickle Charge

• A charging ring and a graph of the session

• Estimated time until fully charged

• A notice when charging seems to have paused, for example with Optimized Battery Charging

COMPARE CHARGERS AND CABLES

• Create benchmark tests for a battery range (for example 30% → 80%) and run one with each charger or cable

• Compare the results for the same range

• See which charger or cable performs best

CHARGING HISTORY

• Sessions are saved automatically with average watts, duration and battery range

• Label each session with the charger you used

• Compare sessions over time to spot a slow cable or an aging charger

MADE FOR YOUR DEVICE

• Has the battery size of every iPhone and iPad that runs iOS 18.6: from iPhone XS to iPhone 18 Pro Max and iPhone Duo, and from older iPads to the latest iPad Pro (M5)

• On a few iPhone Pro models Watt asks once whether your iPhone has a SIM card tray, because the battery differs slightly. You can change the answer in Settings

• On iPad and an open iPhone Duo, the charging ring and status stay on screen while you switch between Details and Benchmark

PRIVATE, ONE PRICE

• Pay once: no subscription, no ads, no account

• No tracking. All data stays on your device

• Works offline

FEEDBACK

Something looks off, or you have an idea? Tap Send Feedback in Settings or in How It Works. It opens an email with your app version, iOS version and device model filled in.

GOOD TO KNOW

iOS pauses apps in the background, so keep Watt Charging Speed open while it follows your charge. It keeps the screen awake during a session so nothing is interrupted.

Perfect for testing a new charger, finding out why charging feels slow, or settling which of your cables belongs in the drawer.