Best Portable Chargers

We reviewed portable chargers across actual capacity versus advertised capacity, charging speed for modern devices, number of simultaneous outputs, weight and density, and safety certifications.

Stated mAh capacity and actual delivered charge are not the same number. A 20,000 mAh power bank delivers roughly 65-70% of its capacity to your device -- about 13,000-14,000 mAh -- due to voltage conversion losses. This is normal physics, not deception, but it means a phone with a 4,000 mAh battery will charge about 3-3.5 times from a 20,000 mAh bank in real use. Advertised wh capacity is the more accurate cross-brand comparison metric.

Pass-through charging -- charging the power bank and your device simultaneously from one wall outlet -- is useful but can be slow. Most power banks in pass-through mode prioritize the device being charged and charge the bank slowly. If you depend on quick recharging of the bank itself between trips, verify the bank's own recharge speed from a fast charger independently of what it outputs to devices.