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Battery mAh ↔ Wh Converter (Power Bank Airline Rules)

Power banks, laptops and drone batteries print "mAh" on the label, but airlines measure batteries in watt-hours (Wh). Enter capacity and the nominal voltage to convert instantly — and to check the IATA Dangerous Goods 100 Wh / 160 Wh thresholds in real time, so you know whether the battery is allowed in the cabin. Wh = mAh × V ÷ 1000.

Common battery voltages

Airline carry-on rules (IATA DGR)

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Based on IATA Dangerous Goods Regulations §2.3.5.9 for lithium-ion / lithium-metal batteries. Wh = mAh × V ÷ 1000. Always confirm with your airline before flying.

Formula

Wh = mAh × V ÷ 1000 mAh = Wh × 1000 ÷ V Airline rules (IATA DGR §2.3.5.9): ≤ 100 Wh → carry-on, no approval needed 100–160 Wh → carry-on only with airline approval, max 2 spares > 160 Wh → forbidden as passenger baggage

Frequently asked

Can I bring my 20 000 mAh power bank on a plane?

Almost certainly yes. Power banks are rated at the 3.7 V cell voltage: 20 000 × 3.7 ÷ 1000 = 74 Wh, well under the 100 Wh threshold. Allowed in carry-on without approval. Keep it in carry-on (never checked) and note that most airlines limit you to 2–4 spare batteries.

For a power bank, should I use 3.7 V or 5 V?

Always use 3.7 V. The mAh figure printed on a power bank is the internal cell capacity at the 3.7 V Li-ion voltage. The 5 V on USB is just the regulated output (after a boost converter with conversion losses), so using 5 V would overstate Wh by about 35 %. Airlines also use the 3.7 V figure.

My drone battery is over 100 Wh — can I still take it on a flight?

If the pack falls between 100 Wh and 160 Wh (e.g. DJI Inspire 3 TB51 ≈ 99.45 Wh, some 4S+ packs > 100 Wh) you need written approval from the airline before flying, with a maximum of two spares per passenger. Anything over 160 Wh (cinema cameras, large mapping drones) cannot fly as passenger baggage and must be shipped via cargo as dangerous goods (DGR Class 9).

Why does my laptop say 99 Wh but my Wh × mAh math comes out different?

Laptop packs run multiple cells in series, with nominal voltages typically 11.4–11.55 V (3S) or 15.4 V (4S) — not 3.7 V. Using 3.7 V would be off by 3×. Most manufacturers (Apple, Lenovo, Microsoft) publish both Wh and V on their spec sheets, so just use the Wh figure directly. The 99 Wh that almost every premium laptop now ships at is deliberate: it keeps the pack under the 100 Wh airline threshold.

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