Power Banks on Planes in 2026: Watt-Hour Rules, the mAh Math, and the New In-Flight Bans

Pack this before you read the rest: every power bank and spare lithium battery must travel in your carry-on, never in checked luggage — and the limit that actually decides your day is written in watt-hours (Wh), not the milliamp-hours (mAh) printed on the case. Anything up to 100 Wh flies with no permission. Between 100 and 160 Wh you need the airline's approval, and you are usually capped at two. Above 160 Wh, a power bank is banned from passenger aircraft outright. After a run of cabin battery fires in 2025, several Asian carriers added a further layer: you may carry your power bank, but you may not use it, charge it, or stow it in the overhead bin in flight.

Why carry-on, never checked

A lithium cell that overheats — a fault called thermal runaway — can climb to several hundred degrees and reignite even after it looks extinguished. In the cabin, a crew member with an extinguisher and water is metres away and trained for exactly this. In the cargo hold, nobody would see the smoke until it was a serious fire. That single difference is why the rule is absolute: batteries ride with the passengers. It is also why gate agents sometimes fish a power bank out of a bag they are about to check at the aircraft door.

The three watt-hour tiers

Aviation authorities rate batteries by energy — watt-hours — not by the marketing number on the label. The International Civil Aviation Organization (ICAO) and IATA set three bands that the FAA, EASA and national regulators all follow:

• Under 100 Wh — no approval, no fuss. Phones, laptops and everyday power banks all sit here.
• 100–160 Wh — allowed only if the airline agrees, and normally limited to two spares. This is the band for oversized "power station" packs and some professional camera batteries.
• Over 160 Wh — forbidden on passenger flights. Batteries this large move as regulated cargo, not in your bag.

How to turn mAh into watt-hours

Your power bank shouts a number like "20,000 mAh," but security cares about watt-hours. The conversion is simple arithmetic:

Wh = mAh ÷ 1,000 × 3.7 V — where 3.7 volts is the nominal voltage of a lithium-ion cell.

So a 20,000 mAh bank is 20,000 ÷ 1,000 × 3.7 = 74 Wh, comfortably legal. You have to climb to roughly 27,000 mAh before you reach the 100 Wh line, which is why a "26,800 mAh" bank — about 99 Wh — is a deliberately common size, built to sit just under the limit. The packs that get stopped are the 30,000 mAh-and-up units, which cross into the approval-only band.

Two habits save you at the checkpoint. First, buy a bank that clearly prints its Wh rating on the case: if an inspector cannot read the number, they are entitled to refuse it. Second, tape over the exposed terminals of any loose spare battery so it cannot short against keys or coins — that short is the exact failure that starts a fire.

The 2025 in-flight crackdown

The rules tightened after a specific event. On 28 January 2025 an Air Busan Airbus A321 caught fire on the ground at Busan, South Korea; all 176 people on board evacuated with only minor injuries, and investigators tied the blaze to a power bank stored in an overhead bin. From 1 March 2025 South Korea's carriers banned power banks and e-cigarettes from overhead compartments — you must keep them on your person — barred charging them from seat USB ports, and capped passengers at five power banks. EVA Air of Taiwan went further and prohibited using portable chargers during flights, while Singapore Airlines, Scoot, Thai Airways and China Airlines reviewed and updated their own lithium-battery guidance. None of this changes the watt-hour limits; it changes what you may do with the battery once you are aboard — so the wording now varies carrier by carrier.

What this means on a Nepal trek

On the trail, a big power bank stops being a luxury. Teahouse lodges in the Everest and Annapurna regions typically charge your devices by the hour for a fee, the sockets are shared, and higher up the electricity is solar and slow — so a 20,000 mAh bank (74 Wh) that keeps a phone, headtorch and GPS alive for several days is one of the smartest things in your pack, and it flies with no paperwork. The trap is going too big: a 30,000 mAh "trek-proof" giant can tip past 100 Wh and demand airline approval you never arranged. For most trekkers, one or two 20,000 mAh banks is the sweet spot. For the plug side of the kit — Nepal's 230 V Type C/D/M sockets and which universal adapter to bring — see our travel adapters and power banks guide. Then it is just the mountains left to plan: our 14-day Everest Base Camp trek and other guided departures run right through the trekking seasons.

Cover photo: Lukas Blazek via Pexels (Pexels License).