Short answer: for daily phone top-ups, 5,000–10,000mAh is enough. For a weekend away, 20,000mAh. For laptops, camping or multi-day trips off-grid, you need 50,000–100,000mAh with at least 100W USB-C Power Delivery. Capacity decides how many charges you get; wattage decides how fast they happen. Most people overbuy on capacity and underbuy on wattage.
What does mAh actually translate to?
A modern smartphone battery holds roughly 4,000–5,500mAh. But you never get the full rated capacity out of a power bank — voltage conversion loses about 20–35%. A realistic rule of thumb:
| Power bank capacity | Realistic phone charges | Best for |
|---|---|---|
| 5,000mAh | ~1 | Pocket carry, commutes |
| 10,000mAh | ~2 | Day trips, festivals |
| 20,000mAh | ~3–4 | Weekends, flights |
| 50,000mAh | ~9–10 | Camping, laptops |
| 100,000mAh | ~18–20 | Off-grid, job sites, group travel |
Wattage matters more than most buyers realise
A 100,000mAh bank rated at 10W will trickle-charge a laptop for hours. The same capacity at 140W will fill a MacBook Pro to around 50% in half an hour. Watts are the number to check on the spec sheet:
- 18–22.5W — fast enough for any phone
- 65W — handles most ultrabooks and tablets
- 100–140W — full-speed laptop charging, and can run several devices at once
Our 100,000mAh 140W portable power bank sits at the top of that range, with USB-C, Lightning and triple USB outputs plus a digital percentage display, at $25.99.
MagSafe and magnetic banks: convenience versus speed
Magnetic wireless power banks snap to the back of an iPhone and charge without a cable. The trade-off is efficiency — wireless charging loses more energy as heat, so you get fewer full charges from the same capacity. They are excellent for walking around; less ideal as your only charger on a long trip.
Three worth comparing:
- Ultra-thin magnetic wireless power bank (5,000/10,000mAh) — the pocket option, also charges Apple Watch. $35.99
- 20,000mAh magnetic MagSafe-compatible bank with 22.5W PD — the balance point between size and staying power. $28.99
- 50,000mAh magnetic wireless bank, PD 25W — high capacity in a slim body. $9.99
Built-in cables save you from the thing you always forget
The most common power bank failure is not a flat battery — it is leaving the cable at home. Banks with integrated cables solve this permanently. The 120W fast-charging power bank with built-in cable comes in 50,000, 100,000 and 200,000mAh versions with USB-C, dual USB and an LED display, from $28.99.
Frequently asked questions
Can I take a power bank on a plane?
Power banks must go in carry-on baggage, never checked luggage. Most airlines follow the 100Wh limit, which is roughly 27,000mAh at 3.7V. Banks between 100Wh and 160Wh usually need airline approval in advance, and anything above 160Wh is generally refused. A 100,000mAh bank is around 370Wh, so it is a ground-travel and camping tool, not a flight companion. Always check your specific airline before you fly.
Does a higher mAh number charge my phone faster?
No. Capacity determines how many charges you get. Speed comes from wattage and the charging protocol — look for USB Power Delivery (PD) or Quick Charge support.
How long do power banks last?
Most lithium-ion cells hold up for 300–500 full charge cycles before capacity noticeably drops. Storing a bank at around 50% charge rather than empty or full extends its usable life.
Is it safe to leave a power bank charging overnight?
Modern banks include over-charge protection and stop drawing current when full. Charge on a hard surface rather than on a bed or sofa so heat can escape.
Browse more
See the full power banks and chargers collection at FanzyMarket.