Best Power Bank for Travel & Flying (2026): The 100Wh Airline Rule, Explained
The right travel power bank keeps your phone, tablet and laptop alive on long days out — but the wrong one can get confiscated at airport security. The trick is understanding two numbers (mAh and Wh) and one rule (the 100Wh airline limit). Here's everything you need.
mAh vs Wh — and why airlines care about Wh
Capacity is advertised in mAh, but airlines regulate in watt-hours (Wh). The conversion: Wh = mAh × 3.7 ÷ 1000. So a 20,000 mAh bank is about 74 Wh. Don't want to do the math? Our free Power Bank Calculator converts it and tells you instantly if a bank is flight-legal.
The 100Wh airline rule
Almost every airline lets you carry power banks up to 100Wh in carry-on with no approval — that's roughly 27,000 mAh. From 100–160Wh you usually need airline approval, and over 160Wh they're banned. Power banks must always go in carry-on, never checked luggage.
How big should you go?
- Phone-only, light traveller: a slim 10,000 mAh (~37Wh) — pockets easily, charges a phone ~2×.
- Phone + tablet, all-day: 20,000 mAh (~74Wh) — the sweet spot, still flight-legal.
- Laptop too: look for ~25,000 mAh with USB-C Power Delivery (65W–100W) so it can actually charge a laptop, not just trickle it.
Don't ignore charging speed
A huge battery that only outputs 10W is frustrating. For a phone, 20W+ USB-C PD tops up fast; for a laptop, you want 65W+. More ports help if you're charging several devices at once.
What to buy
See our current top-rated picks in the power & charging guide, or let us match you in 20 seconds with the Power Bank Finder quiz.
Frequently asked questions
Can I bring a power bank on a plane?
Yes — power banks up to 100Wh (about 27,000 mAh) are allowed in carry-on with no approval on virtually all airlines. From 100–160Wh you typically need airline approval; over 160Wh they're prohibited. They must travel in carry-on, never checked baggage.
How do I convert mAh to Wh?
Watt-hours = mAh × voltage ÷ 1000. Power bank cells are 3.7V, so a 20,000 mAh bank = 20000 × 3.7 ÷ 1000 = 74Wh. Airlines use the Wh figure.
What size power bank do I need?
10,000 mAh charges a phone about twice and is great for light travel; 20,000 mAh is the all-day sweet spot and still flight-legal; ~25,000 mAh with 65W+ USB-C PD is best if you also charge a laptop.
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