How to Charge a Phone With Another Phone

You can charge one phone from another using a power bank or a USB cable, but the phone doing the charging must have enough battery to share

Charging one phone from another works in two ways: with a power bank (a portable battery that stores charge), or directly between two phones using a USB cable and the right adapter. A power bank is the practical choice for most people because it's designed for this job and won't drain your phone's battery to dangerous levels. Direct phone-to-phone charging is possible but uncommon—most phones aren't built for it, and doing it wrong can damage both devices.

The method you choose depends on what devices you have, how much charge you need, and whether you have the right cables on hand. Neither method is a permanent solution, but both work in emergencies when you need to get a phone to a usable battery level quickly.

Key Takeaways

A power bank is the safest and most practical way to charge a phone from another device, and it won't drain your phone's battery completely.
Direct phone-to-phone charging requires a USB cable with the correct connector for both phones and only works if your phone supports it—most don't.
Charging speed depends on the power bank's capacity (measured in mAh) and the cable type; USB-C cables charge faster than older Micro-USB or Lightning connectors.
Power banks come in different sizes: small ones (5,000 mAh) fit in a pocket, while larger ones (20,000+ mAh) can charge a phone multiple times before needing to recharge themselves.
Avoid draining your phone below 20 percent battery before charging another device from it, as this can damage your phone's battery over time.

Using a power bank to charge another phone

A power bank is a portable battery with one or more USB ports. You charge the power bank itself at home or in a car, then use it to charge your phone or another device later. This is the method most people use because it's safe, fast, and doesn't require the phone doing the charging to give up its own battery.

To use a power bank, plug your phone's charging cable into one of the power bank's USB ports. The power bank will begin charging your phone when ready. Most power banks have a button you press to turn them on, though some start automatically when you plug in a device. A light on the power bank shows how much charge it has left—when the light goes out or turns red, the power bank itself needs to be recharged.

Power banks are measured in mAh (milliamp-hours), which tells you how much total charge they hold. A 5,000 mAh power bank will charge most phones once. A 10,000 mAh power bank will charge most phones twice. A 20,000 mAh power bank or larger can charge a phone three or more times. The larger the power bank, the heavier it is, so choose based on how often you'll need it and how much you're willing to carry.

Charging directly between two phones

Some newer phones can charge other phones directly using a USB cable, but this method has real limits. Your phone must support reverse charging (also called reverse wireless charging), which is a feature only some high-end phones have. Even if your phone has this feature, the other phone must have the right connector type—USB-C, Micro-USB, or Lightning—and the cable must fit both devices.

To charge another phone directly, connect a USB cable to both phones. On the phone doing the charging, you may need to go into Settings and enable reverse charging or power sharing. The phone receiving the charge should recognize it as a power source and begin charging. This process is much slower than using a power bank and will drain your phone's battery quickly, so only use it in emergencies.

Direct phone-to-phone charging can damage both phones if done incorrectly. Never attempt it if you don't know whether your phone supports the feature, and avoid doing it repeatedly, as it puts stress on both batteries. If you're not sure whether your phone has reverse charging, check the manufacturer's website or your phone's settings menu.

Cable types and charging speed

USB-C cables charge the fastest and are now standard on most Android phones and newer iPhones. A USB-C power bank or cable can deliver more power than older connector types, so your phone will charge in less time. If you're buying a power bank, choose one with USB-C ports if your phone has a USB-C charging port.

Micro-USB cables are older and charge more slowly than USB-C. Many Android phones still use Micro-USB, and older power banks often have Micro-USB ports. If your phone uses Micro-USB, a power bank with a Micro-USB port will work, but charging will take longer than with USB-C.

Lightning cables are Apple's connector type for iPhones and iPads. Power banks with Lightning ports exist, but they're less common and often more expensive. Many power banks have USB-A ports (the older rectangular USB ports) instead, so you'll need to bring a separate Lightning cable to charge an iPhone from a power bank.

How much battery you'll actually get

A power bank doesn't transfer all of its rated capacity to your phone. A 10,000 mAh power bank won't give your phone a full 10,000 mAh of charge because some energy is lost in the transfer process. In practice, you'll get about 60 to 80 percent of the power bank's rated capacity, depending on the cable quality and the phone's battery size.

For example, a 10,000 mAh power bank might add 6,000 to 8,000 mAh to your phone's battery. If your phone's battery is 4,000 mAh, that power bank could charge it once or twice. Check your phone's battery capacity in Settings to estimate how many charges a power bank will give you. Most phones show battery capacity in mAh or watt-hours (Wh).

Protecting your phone's battery while charging another device

Charging another phone from your phone's battery is hard on your device. Every time you drain your phone significantly to charge something else, you're putting stress on the battery and shortening its lifespan. Avoid letting your phone drop below 20 percent battery before charging another device from it.

If you regularly need to charge other devices, invest in a power bank instead. A power bank costs less than replacing your phone's battery and won't damage your phone in the process. Keep the power bank charged at home so it's ready when you need it. This approach is faster, safer, and easier on your phone's battery than direct phone-to-phone charging.

Choosing the right power bank for your needs

When shopping for a power bank, consider three things: capacity (mAh), connector type, and size. A small 5,000 mAh power bank fits in a pocket and charges most phones once—good if you just need a backup for emergencies. A medium 10,000 to 15,000 mAh power bank charges most phones twice and is still portable. A large 20,000+ mAh power bank charges phones multiple times but is heavier and bulkier.

Match the connector type to your phone. If your phone has USB-C, buy a power bank with USB-C ports. If you have multiple phones with different connectors, look for a power bank with multiple port types or one with USB-A ports so you can use different cables. Check the power bank's wattage (measured in watts or W) if you have a newer phone—higher wattage means faster charging, but your phone will only draw as much power as it needs.

Read reviews before buying. Some power banks charge slowly, overheat, or stop working after a few months. Brands with good track records include Anker, Belkin, and Mophie, though many other brands work well too. Avoid extremely cheap power banks, as they may not charge safely or reliably.

Frequently Asked Questions

Can I charge an iPhone from an Android phone?

Yes, if you have the right cable. iPhones use Lightning connectors, and most Android phones use USB-C or Micro-USB. You'll need a power bank with a Lightning port, or a power bank with USB-A ports and a separate Lightning cable. Direct phone-to-phone charging between an iPhone and Android phone is not possible because they use different connector types.

Will charging another phone damage my battery?

Yes, if you do it repeatedly. Draining your phone to charge another device stresses the battery and reduces its lifespan. Doing it once in an emergency is fine, but if you need to charge other devices regularly, use a power bank instead. This protects your phone's battery and charges faster.

How long does it take to charge a phone with a power bank?

Most phones charge from zero to full in one to three hours with a power bank, depending on the power bank's wattage and your phone's battery size. USB-C power banks charge faster than Micro-USB ones. Check the power bank's wattage rating—higher wattage means faster charging, but your phone will only accept the power it needs.

Can I use a power bank while it's charging another phone?

Yes, but it will charge more slowly. If you plug a power bank into a wall outlet while it's charging your phone, it will do both at once, but the phone will charge slower than if the power bank was fully charged first. For fastest charging, charge the power bank fully before using it to charge your phone.

What's the difference between a power bank and a portable charger?

They're the same thing—"power bank" and "portable charger" are just different names for the same device. Both are portable batteries that store charge and plug into your phone's charging port. Some people use "portable charger" for smaller models and "power bank" for larger ones, but the terms are interchangeable.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.