Charging time depends on three things: your charger, your battery size, and what you're doing while it charges

A phone or tablet battery typically charges from empty to full in one to three hours, but the real answer depends on which charger you're using, how big your battery is, and whether you're using the device while it charges. A standard charger that came with your device will take longer than a fast charger. Using your phone while it charges — especially for video or gaming — will add 30 minutes to an hour to the total time. Turning on airplane mode or letting it sit idle cuts charging time noticeably.

The most common mistake is assuming all chargers work the same way. They don't. A charger rated at 5 watts will charge much slower than one rated at 18 watts or higher. If you've switched chargers or borrowed one from someone else, that's often why your device suddenly charges slowly.

Key Takeaways

  • Standard chargers take two to three hours for a full charge, while fast chargers can do it in 45 minutes to an hour and a half.
  • The wattage printed on your charger (5W, 18W, 20W, etc.) directly affects speed — higher wattage means faster charging.
  • Using your device while charging, especially for apps that use a lot of power, will significantly slow down the charging process.
  • Wireless chargers are slower than wired chargers and typically add 50 percent more time to a full charge.
  • Battery age matters — older batteries charge more slowly than new ones, even with the same charger.

What the wattage number on your charger actually means

Every charger has a wattage rating printed on it or on the cable. This number — 5W, 10W, 18W, 20W, 30W, or higher — tells you how much power the charger can deliver to your battery at once. Think of it like a water faucet: a 5-watt charger is a thin stream, and a 30-watt charger is a full flow. The higher the wattage, the faster the battery fills.

Your device will only accept as much power as it's designed to handle. A phone designed for 20-watt charging won't charge any faster if you plug it into a 65-watt charger — it will straightforward use what it needs and ignore the rest. But if you use a charger with lower wattage than your device supports, charging will be noticeably slower. For example, charging a tablet designed for 30-watt charging with a 5-watt phone charger can take four to five hours instead of one and a half.

The original charger that came with your device is almost always the right wattage for that device. If you've lost it or switched to a different one, check the wattage on both chargers and compare them to your device's manual or the manufacturer's website.

Why using your device while charging makes it take longer

When you use your phone or tablet while it's plugged in, the battery has to power two things at once: the screen, apps, and processor running your activity, and the charging circuit filling the battery. This split in power means less energy goes into charging, so the process slows down. Scrolling through social media or reading adds a small delay. Video streaming, gaming, or video calls can add 30 minutes to an hour or more.

The device also generates heat when it's working hard and charging at the same time. Most modern devices have built-in safety features that slow down charging if the battery gets too warm, which is another reason why heavy use during charging extends the total time. If you want the fastest charge, turn off the screen, close all apps, or turn on airplane mode and let the device sit.

Wireless charging versus wired charging

Wireless chargers are convenient but slower. A wireless charger typically takes 50 to 100 percent longer than a wired charger — so if a wired charger takes two hours, expect three to four hours with wireless. This is because wireless charging transfers power through the air gap between the charger pad and the device, which is less efficient than a direct cable connection.

Some newer wireless chargers are rated as "fast wireless chargers" and are faster than older models, but they still won't match a wired fast charger. If you need your device charged quickly, use the wired charger. Wireless charging is best for overnight charging or when you have time to spare.

How battery age affects charging speed

A new battery charges faster than an old one, even with the same charger. As batteries age — typically after 300 to 500 full charge cycles — they hold less charge and accept power more slowly. This is normal wear and not a sign of a problem with your charger. A phone that charged in two hours when new might take two and a half or three hours after two years of use.

You can't reverse this slowdown, but you can slow it down further by following basic battery care: avoid letting the battery drop to zero percent regularly, don't leave it plugged in for hours after it reaches 100 percent, and keep the device cool while charging. If charging has become extremely slow — taking four or five hours for a full charge on a device that used to take two — the battery may be near the end of its useful life and replacing it could restore charging speed.

Charging speed on different device types

Phones typically charge faster than tablets because they have smaller batteries. A smartphone battery might be 3,000 to 5,000 milliamp-hours (mAh), while a tablet battery can be 7,000 to 10,000 mAh or larger. A larger battery takes longer to fill, even with a high-wattage charger. Laptops with large batteries can take two to four hours even with a powerful charger.

Smartwatches and earbuds charge very quickly — often 30 to 60 minutes — because their batteries are tiny. Portable battery packs (power banks) vary widely depending on their capacity, but most take two to four hours to charge fully. Check your device's manual for the battery capacity and recommended charger wattage to understand what's normal for your specific device.

What to do if your device is charging much slower than usual

If charging time has suddenly increased, start by checking three things: the charger wattage, the cable condition, and what's running on your device. Swap in the original charger if you have it. Look at the cable for damage — a bent connector or frayed wire reduces charging speed. Close all apps and turn on airplane mode to eliminate power drain.

If charging is still slow, try a different outlet. Some outlets deliver less power than others, especially if they're on the same circuit as other high-power devices. If the problem persists across multiple chargers and outlets, the battery itself may be aging faster than normal, or there may be a hardware issue. At that point, contact the device manufacturer or visit a repair shop.

Frequently Asked Questions

Is it bad to leave my device plugged in after it reaches 100 percent?

Modern devices have built-in protections that stop charging once the battery reaches 100 percent, so leaving it plugged in overnight won't damage the battery when ready. However, keeping a battery at 100 percent for extended periods does cause gradual wear over months and years. If you charge overnight regularly, unplugging as soon as it's full will extend battery life slightly.

Why does my device charge faster when it's cold?

It doesn't — it actually charges slower when cold. A cold battery accepts power more slowly as a safety feature to prevent damage. You may notice faster charging in a cool room because the device isn't generating as much heat during charging, which allows it to accept more power without triggering thermal slowdown. The ideal charging temperature is between 50 and 95 degrees Fahrenheit.

Can I use a charger with higher wattage than my device recommends?

Yes, it's safe. Your device will only draw the power it needs and ignore the rest. A 65-watt charger won't harm a phone designed for 20-watt charging. However, using a charger with significantly lower wattage than recommended will charge slowly. Always match the wattage to what your device supports for the fastest safe charging.

Does fast charging damage the battery?

Modern fast chargers are designed to be safe and include temperature monitoring and power regulation. Using the manufacturer's recommended fast charger won't damage the battery. However, using a third-party fast charger that doesn't properly regulate power can generate excess heat and cause faster wear over time. Stick with chargers from the device manufacturer or reputable brands that support your device model.

Why does charging slow down as the battery gets fuller?

Most devices automatically reduce charging speed in the final 20 to 30 percent of a charge to protect the battery from stress and heat. This is why the last bit of charging often takes as long as the first 70 percent. This is normal and intentional — it extends battery lifespan at the cost of slightly longer total charging time.