A good power bank keeps your phone alive through long travel days, festivals and power cuts. But capacity numbers are misleading, and many power banks charge phones slowly because they don't support the right fast-charging standard. Here's how to pick one that genuinely delivers.
1. Capacity: what the mAh really means
Power banks list capacity at the internal battery voltage (about 3.7V), but phones charge at higher voltages through conversion, losing energy. Real usable capacity is typically 60–70% of the rated number.
| Rated capacity | Real phone charges (5,000mAh phone) |
|---|---|
| 5,000mAh | ~0.6–0.7 |
| 10,000mAh | ~1.2–1.5 |
| 20,000mAh | ~2.5–3 |
Watt-hours (Wh) are a clearer measure: 10,000mAh ≈ 37Wh.
2. Fast charging standards
To fast charge, the power bank must speak your phone's language:
- USB Power Delivery (PD): iPhone, Pixel and most modern Android phones
- PPS (Programmable Power Supply): needed for Samsung Super Fast Charging (25W/45W)
- Quick Charge: older Android phones
- Proprietary (SUPERVOOC, HyperCharge): usually only works at full speed with brand power banks
Look for "USB-C PD 3.0 with PPS" for the widest compatibility.
3. Output wattage
- 20–30W: fast enough for iPhones and most phones
- 45W: Samsung Ultra super fast charging, tablets
- 65–140W: laptops too
Check per-port output; total wattage is shared when multiple devices charge.
Photo by Lukas Blazek on Pexels
4. Useful features
- Pass-through charging: charge the power bank and phone at the same time
- Built-in cables (USB-C or Lightning), so you never forget a cable
- Magnetic (MagSafe / Qi2) wireless packs: convenient but slower and less efficient
- Display showing percentage and output wattage
- Recharge speed: fast input (30W+) refills big power banks quicker
5. Size and weight
- 5,000–10,000mAh: pocketable daily carry
- 20,000mAh: travel, weekends
- 25,000mAh+: laptop users, heavier
6. Airline rules
Most airlines allow power banks under 100Wh (about 27,000mAh) in carry-on only, never checked luggage. Some airlines now restrict use during flights. Check your airline's current rules.
7. Safety
- Buy from reputable brands with certifications (CE, UL, etc.).
- Avoid ultra-cheap "50,000mAh" claims.
- Don't use power banks that are swollen, hot or damaged.
- Store at around 50% charge for long periods.
Video buying guide
Summary
Choose a power bank with USB-C PD + PPS, enough per-port wattage for your phone, realistic capacity for your needs, and a trusted brand. You'll get genuinely fast top-ups wherever you are.
Pair it with a phone that charges quickly. Compare models on infozme's fast charging phones list.
Cover photo by Andrey Matveev on Pexels. This article was written with the help of AI.
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