How to check if a tablet charger keeps up

Your tablet is plugged in, but the battery percentage barely rises while you watch a video, play a game, or keep the screen bright. That can mean the charger is supplying less power than the tablet is using, but it can also be normal charging behavior.

Compare the charging rate with the screen mostly idle and during your usual screen activity. The Charger & Cable Test measures charging speed in percent per minute, so you can check whether the battery gains charge, holds steady, or continues to drain.

Compare charging with and without screen use

Open the Charger & Cable Test on the tablet you want to check. The test appears only if your browser can read the device's battery information.
Connect the charger directly to a wall outlet. Use the same charger, cable, outlet, and tablet position for both comparisons. Let the battery settle for a few minutes after plugging in.
Measure the charging rate with the screen on but mostly idle. Follow the test's on-screen instructions and note the result in percent per minute.
Keep the tablet plugged in and use it as you normally would for 15 to 30 minutes. For example, watch a video or play a game at your usual brightness, then note the charging rate again.
Compare the two readings. If you need to use another app, keep the test visible in split screen if possible. A browser may pause or slow a page that is hidden in the background.

Battery readings update in whole percentage points, so short tests can look uneven. Use similar starting charge levels for both comparisons, ideally within the same broad range, such as 30 to 60 percent. Charging often slows as the battery gets close to full, and a warm tablet may also reduce its charging rate.

What the result means

The battery still gains charge during screen use

The charger is keeping up under the activity you tested, though the rate may be slower than when the screen is idle. A lower rate is expected when the display, processor, wireless connection, and apps use more power.

The battery percentage stays about the same

The charger is roughly balancing the tablet's power use during that activity. It may take a long time to gain charge while you use the screen, but the result does not by itself mean the charger is faulty. Try a less demanding activity or lower the brightness to see whether the battery starts rising.

The battery continues to fall while plugged in

The tablet is using power faster than it is receiving it at that moment. Repeat the comparison with a different cable and a charger suited to the tablet. If the battery falls with more than one known-good charger during ordinary use, the charging port, battery, or device may need attention.

The reading jumps around or does not appear

A short test can be affected by rounded battery percentages, changes in temperature, and changing screen activity. If no battery reading appears, the browser may not provide battery information on that device. Charger & Cable Test and Battery Meter are available only on devices whose browser reports a battery, including some laptops, tablets, and phones.

How to improve charging during use

Try a different wall outlet. Connect the charger directly to an outlet instead of a computer, monitor, or unpowered hub. If you use a power strip, check it with another outlet.
Check the cable and charger rating. A cable or adapter can limit charging even when it fits the port. Use a charger and cable that support the tablet's charging standard and power needs. A browser test measures battery change, not the charger's exact wattage.
Reduce screen and app use for a comparison. Lower brightness, pause high-resolution video, and close games or apps you are not using. If the battery starts gaining charge, the charger may be adequate for lighter use but not for the heavier activity.
Let the tablet cool down. Unplug it and stop demanding apps if the device feels unusually hot. Charging can slow when a battery or device gets hot. Do not cover it while charging, and do not keep testing a swollen or damaged device.
Check battery and charging settings. On a Windows 11 tablet, open Settings › System › Power & battery. On an iPad, check Settings › Battery. Android menu names vary, but look under Settings › Battery for battery protection, optimized charging, or a charging limit. These features can pause or limit charging by design.
Inspect the charging port carefully. Check for visible lint, damage, or a loose connection. Do not push metal objects into the port. If the plug only works at an angle, stop relying on that connection and arrange a repair.
Restart the tablet and test again. A restart can close an app that is using unusually high power. Repeat both measurements under the same conditions before drawing a conclusion.

When the charger or tablet may be faulty

Test with a compatible charger and cable that work properly with another device, if available. If the tablet still loses charge during ordinary screen use with more than one suitable charger, but charges normally when turned off, the device may be drawing too much power or have a battery problem. If charging cuts in and out when the plug moves, the cable or port is a stronger suspect.

Stop using a charger, cable, or tablet that is cracked, frayed, smells burnt, or becomes painfully hot. For a device under warranty, contact the manufacturer or seller before opening it. A damaged port or battery should be checked by a qualified repair shop.

Why percentage per minute is not a wattage reading

The test estimates how quickly the battery percentage changes. It does not measure the electrical power coming from the charger, and it cannot identify the charger's rated wattage. Battery percentage is rounded, and the device changes its charging rate as the battery fills or warms up. That is why a fair comparison uses the same tablet, charger, cable, outlet, and similar starting battery levels.