How to Choose the Right Power Bank: A No-Nonsense Buying Guide
Power banks all look the same on the outside, but the specs inside can make a huge difference. Here’s how to cut through the marketing and find the right one for your needs.
Understanding Capacity (mAh)
The most advertised spec is milliamp-hours (mAh) – but bigger isn’t always better.
| Capacity | Real-World Usage | Best For |
|---|---|---|
| 5,000 mAh | ~1 full phone charge | Quick top-up, ultra-light carry |
| 10,000 mAh | ~2 full phone charges | Daily carry, moderate usage |
| 20,000 mAh | ~4 full phone charges | Heavy usage, travel, multiple devices |
| 30,000+ mAh | ~6+ phone charges | Extended trips, laptop charging |
Important: Actual output is typically 60-70% of rated capacity due to conversion losses. A 10,000 mAh bank delivers about 6,500-7,000 mAh of usable charge.
Wattage Matters More Than You Think
A power bank’s output wattage determines how fast it charges your device:
- 5W-10W: Very slow – your phone charges at a crawl
- 18W-22.5W: Fast charging – most modern phones charge at full speed
- 45W-65W: Laptop-grade – can charge ultrabooks and tablets
- 100W+: High-performance – for power-hungry devices
Pro tip: Also check the input wattage. A 20,000 mAh bank with 5W input takes 15+ hours to recharge itself. Look for at least 18W input.
Port Types
- USB-C (with PD): The gold standard. Fast in, fast out. Charges phones and laptops.
- USB-A: Legacy port. Works with older cables. Usually slower output.
- MagSafe/wireless charging pad: Convenient but slower (5-15W typically).
What About Airline Regulations?
For flights, power banks must be under 100Wh (approximately 27,000 mAh at 3.7V). Most 20,000 mAh power banks are around 74Wh, so they’re safe to carry on.
Cannot be checked in – power banks must always go in your carry-on luggage.
Our Pick
The Havit MagSafe Power Bank offers 10,000 mAh in a slim, magnetic form factor. It snaps onto the back of your iPhone for wireless charging on the go, while the USB-C port delivers fast wired charging for any device.