Understanding mAh Ratings

mAh stands for milliampere-hour, which is a unit of electric charge. It indicates how much charge a battery can hold and therefore how long it can power your devices.

For power banks, the mAh rating tells you the total capacity available to charge your devices. However, it’s important to note that due to energy conversion losses (from the power bank’s battery to your device’s battery), the actual usable capacity is typically about 60-70% of the rated capacity.

Power Bank Capacity Guide

Capacity Range	Best For	Device Charges*
3,000 – 5,000 mAh	Emergency use, compact option	1-1.5 smartphone charges
10,000 mAh	Day trips, most users	2-3 smartphone charges
20,000 mAh	Weekend trips, multiple devices	4-6 smartphone charges
27,000+ mAh	Extended travel, power-intensive devices	6+ smartphone charges or 1-2 laptop charges

*Based on average smartphone battery of 3,000-4,000 mAh

Factors to Consider When Choosing Capacity

1. Your Device’s Battery Size

Check your smartphone or tablet’s battery capacity (usually found in specifications) to determine how many charges you might need.

2. How Many Devices You Need to Charge

If you need to charge multiple devices, you’ll want a higher capacity power bank.

3. How Often You’ll Use It

Daily users might prefer a lighter, lower capacity bank, while travelers may prioritize higher capacity.

4. Portability Needs

Higher capacity power banks are larger and heavier. Consider what you’re willing to carry.

5. Output Power

For fast charging or powering larger devices like tablets or laptops, look for higher output (measured in watts or amps) in addition to capacity.

Power Bank Capacity Calculator

Remember that due to efficiency losses (typically 30-40%), you’ll need a power bank with about 30% more capacity than your calculated need.

Beyond mAh: Other Important Features

Output Ports and Power

Check the output amperage (e.g., 2.4A) and number of ports. More ports allow charging multiple devices simultaneously.

Input Charging Speed

How quickly the power bank itself can be recharged. Look for technologies like Power Delivery or Quick Charge for faster recharge times.

Size and Weight

Higher capacity usually means larger size and weight. Consider portability if you’ll carry it daily.

Safety Features

Look for protection against overcharging, short circuits, and overheating.

Pass-Through Charging

Allows the power bank to charge devices while being charged itself.

Common Power Bank Myths

Myth 1: Higher mAh Always Means Better

While capacity is important, extremely high capacity power banks are larger, heavier, and may be unnecessary for most users.

Myth 2: All 10,000 mAh Power Banks Are Equal

Actual performance varies based on battery quality, efficiency, and output power. Brand reputation matters.

Myth 3: You Can’t Take Power Banks on Planes

You can typically bring power banks in carry-on luggage, but there are capacity limits (usually 27,000-32,000 mAh maximum).

Myth 4: Leaving Your Power Bank Charging Overnight Damages It

Most modern power banks have built-in circuits to prevent overcharging, but it’s still best practice to unplug when fully charged.