A power bank is one of those accessories you barely think about - until your phone hits 4% on a long day and you wish you had one in your bag. The good news is that choosing a power bank is much simpler than the spec sheets make it look. Almost everything boils down to two questions: how much capacity do you actually need, and how fast do you want to top up your phone?
Capacity is measured in milliamp hours (mAh), and the numbers can sound dramatic. A 10,000 mAh power bank will give a modern smartphone roughly two full charges. A 20,000 mAh model doubles that to four, but it is also noticeably heavier and bulkier. For most people who just want a safety net for a long day - commute, errands, a flight - a 10,000 mAh bank hits the sweet spot of size and capacity. If you travel often or carry a tablet, a 20,000 mAh bank is the better call. Anything over that starts to feel like a brick in your bag, and unless you actively need it, it is overkill.
Charging speed matters more than most people realise. A cheap power bank can hold plenty of energy, but if it only outputs 10W, refilling your phone takes hours. Look for a model that supports at least 18–20W USB-C Power Delivery (PD). That is enough to get a phone from empty to roughly 50% in about half an hour - the difference between a quick coffee top-up and waiting forever. If you also charge a laptop or tablet on the go, look for 45W or higher.
Pay attention to how the power bank itself recharges. Older models still use micro-USB, which is slow and a hassle to keep cables for. A USB-C input that supports fast input charging means you can refill the power bank itself in two to three hours instead of overnight. That single feature changes how often you actually carry it.
Build quality and safety are the parts no one talks about, but they matter. A reputable brand with proper certifications protects against overheating, overcurrent, and short-circuits. A no-name 30,000 mAh bargain from a marketplace is rarely a deal - it is often a fire risk and a fraction of its claimed capacity. Spend a few euros more on a power bank from a brand that publishes a warranty, and you will use it for years.
The simple takeaway: a 10,000 mAh model with 20W USB-C PD covers 90% of real-world needs in a pocket-friendly size. Go to 20,000 mAh if you travel or share with family. Skip anything bigger unless you really know why you need it.
