Real-world output note: Due to energy loss (heat, voltage conversion), expect about 2/3 of rated mAh as usable charge.
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5,000 mAh: ~1 full charge for most phones (tiny, emergency use only).
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10,000 mAh: 2–3 full charges (sweet spot – best balance of size and capacity).
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20,000 mAh: 4–6 full charges (great for travel, but heavier).
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30,000+ mAh: May not be allowed on airplanes (exceeds most airline limits of 27,000 mAh / 100Wh).
Ports to look for:
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USB-C (in/out): Future-proof, charges both the power bank and your phone.
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USB-A: For older devices and cables.
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Built-in cables: Convenient but less durable (if cable breaks, whole bank is less useful).
Useful features:
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Passthrough charging: Charge the power bank while it charges your phone (convenient for travel).
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Fast charging support: Look for USB-C PD (Power Delivery) and/or QC (Quick Charge) support.
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Digital percentage display: Much more accurate than 4 LED dots.
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Low-current mode: For charging earbuds, watches, or other small devices (prevents auto-shutoff).