Yes, there are fixes to stop your phone, tablet, or laptop battery from draining fast. But not everyone wants to compromise. That's why portable power banks or battery packs exist.

For those who are new to power banks or have difficulty deciding which kind to get, capacity is the first and foremost thing to consider because it determines how often you can charge your device.

Ever wondered what the best capacity for a power bank is?

What Do You Need to Know About Power Bank Capacity?

I once explained about the numbers printed on power banks. Capacity is one of those complicated technical terms. But the rule is simple: the actual capacity of a power bank is about 2/3 of the rated capacity. Part of the energy will be lost in the conversion and during charging.

Capacity typically measures in mAh (Milliamp Hours), like our smartphone batteries. The bigger the number is, the larger the capacity. A power bank with a 10000 mAh battery has a capacity of about 6000-7000 mAh. The iPhone 12 mini has a 2227 mAh battery. So one full charge of a 10000 mAh power bank can charge the iPhone 12 mini from 0 to 100% two or three times (7000 divided by 2227).

If a 10000 mAh power bank can barely charge your iPhone 12 mini twice, then probably it's so poorly made that too much energy loss happens during charging, it has a low conversion efficiency or simply contains far less capacity than claimed.

Power Banks with Low Capacity

1000 mAh Power Bank

Power banks with a capacity less than that of the regular smartphone are rarely seen nowadays. To many, they seem pointless, but those who are not addicted to handheld entertainment may love the idea of a backup battery pack that they can attach to their key chains or keep in their wallet.

4000~5000 mAh Power Bank

 PITAKA MagEZ Battery Pack, 4000mAh

A power bank of about 4000 mAh should suffice in ensuring your phone lasts well over a day even if you're a heavy phone user, given that most people don't leave the house with a dead phone. Phone users welcome these kinds of power banks with good reason: sufficient capacity with portability. If you are looking for a portable power bank for your phone, you may want to look at those 4000-5000 mAh power banks that can fully, or almost fully, charge your device. They're also very portable and convenient to carry.

Power Banks with Medium Capacity

7000 mAh Power Bank

If you're going to places where you regularly rely on your phone, and it may be a while before you come across a wall charger, then a medium-capacity power bank is the best option. A power bank with a capacity of around 7,000 mAh can not only charge your phone once, but you can share it with other people or charge other small devices like earbuds.

10000 mAh Power Bank

The average battery capacity of a standard smartphone falls below 4,000 mAh. So, a power bank with a 10,000 mAh capacity (actual capacity 6,000-7,000 mAh) is enough to fully charge most handsets at least once and charge small phones like the iPhone 12 mini three times. The downside is that power banks of this size tend to be larger and heavier than your cell phone.

20000 mAh Power Bank

A power bank with a capacity of 12000 mAh is more than enough for a smartphone. You can even charge a tablet like the iPad mini (5124 mAh) or Samsung Galaxy Tab S7 (8000 mAh).

If you have the iPad Pro 2020 with a battery of nearly 10000 mAh, or a standard laptop, then a 20000 mAh power bank seems to be the best option. After charging your iPad Pro once, the power bank still has energy left for a smartphone.

Power Banks with High Capacity

20000+ mAh Power Banks

Power banks with a capacity of over 20000 mAh are comparably expensive and sizeable. So, be careful if you see some power banks with an extremely high capacity and an unreasonable price tag. They can support all your portable devices for a day and tend to be used for camping or traveling.

120000 mAh Power Banks

These kinds of power banks are more like portable generators, capable of lasting for days. They are usually found in a car's trunk and can charge appliances, such as a mini-fridge. They typically feature multiple charging ports to charge several devices simultaneously.

What is the Best Capacity for a Power Bank?

As you already know, the more capacity a power bank holds, the more it can provide. On the flip side, the more powerful a power bank is, the bulkier it is. They also require a longer charging time and may not be allowed on flights.

You can't have it both ways.

So, the best capacity for a power bank depends on your needs.

For regular phone use or a daily commute, take a look at power banks between 4000-5000 mAh, which are portable and have adequate juice.

For phone users with unique needs or for particular scenarios, 7000-10000 mAh are good options. If you want a power bank mainly for your tablet or laptop, they'd better be above 10000 mAh.