Power banks are sold on a single number: milliampere-hours (mAh). But what does it mean in practice? In this guide we do the honest maths, so you neither overpay for capacity you will never use, nor get stranded with a battery that is too small.
What does mAh actually tell you?
mAh indicates how much charge a battery can store. A modern smartphone battery holds roughly 3,000 to 5,000 mAh. So you might think a 10,000 mAh power bank charges your phone two to three times. In reality it is less.
The honest part: conversion losses
Charging loses energy to heat and voltage conversion (from 3.7 V inside the power bank to 5 V or more over USB). A realistic figure is 60 to 70% usable capacity. Wireless charging is convenient, but costs extra energy compared to charging over the cable.
| Capacity | Realistically usable | Phone (±4,500 mAh) |
|---|---|---|
| 10,000 mAh | ±6,500 mAh | 1 to 1.5 full charges |
| 20,000 mAh | ±13,000 mAh | 2.5 to 3 full charges |
Which capacity fits you?
- Everyday use and a day out: 10,000 mAh is compact enough to carry by default and easily covers an empty afternoon. See the SYVOX Solar 10K Magnetic, with a built-in cable and magnetic wireless charging.
- A weekend away or several devices: with 20,000 mAh you charge your phone plus earbuds or a tablet several times. The SYVOX Magnetic 20K has its charging cables built in, so you can never forget them.
Can your power bank fly with you?
Yes, but only in your hand luggage, never in the hold. The common limit is 100 Wh, which equals roughly 27,000 mAh. Both SYVOX power banks stay well below it. Always check your airline's rules before you travel.
Frequently asked questions
Is a bigger power bank always better?
No. More capacity means more weight and size. A power bank you leave at home because it is too heavy does not help you. Choose based on how you actually use it.
How long does a power bank last?
Lithium batteries gradually lose capacity; you will notice after hundreds of charge cycles. Avoid storing it fully empty and keep it away from extreme heat: that preserves capacity longest.
Can I charge my power bank and phone at the same time?
Most modern power banks support passthrough charging, or charge the power bank first and your phone after. Practical tip: plug both in overnight and start the day fully charged.