Buying the highest-spec option isn’t always the right call — matching the charger to actual usage patterns usually saves money without costing convenience.
- Match capacity to actual use: a phone battery is roughly 15–20Wh, so a 20,000mAh power bank (about 74Wh) can realistically recharge a phone 3–4 times, not the marketing-friendly number often implied.
- Check output wattage separately from capacity — a huge-capacity power bank with a low-wattage port will charge slowly regardless of how much energy it stores.
- Consider whether you need pass-through charging (using the bank while it charges) if it’ll double as a travel hub.
Rule of thumb
Buy for your most demanding realistic use case, not the theoretical maximum — most people overbuy capacity and underbuy port count.