How do I calculate Wh from mAh?

Multiply the mAh by the battery voltage and divide by 1000: Wh = mAh × V ÷ 1000. At 3.7 V, 20,000 mAh is 74 Wh and 27,000 mAh is 99.9 Wh — just under the 100 Wh limit.

Rules checked on 21 October 2026. Every answer below is from an official source.

What the rules say

Authority or airlineAnswerQuoteSourceChecked
ICAOWorldwide baseline Limit without approval: 100 Wh. — iata.org 21 Oct 2026
FAAUnited States Limit without approval: 100 Wh; 101–160 Wh with airline approval. — faa.gov 21 Oct 2026
UK CAAUnited Kingdom Limit without approval: 100 Wh; 100–160 Wh with operator approval. — caa.co.uk 21 Oct 2026
EASAEuropean Union Limit without approval: 100 Wh; 100–160 Wh with operator approval. — ad.easa.europa.eu 21 Oct 2026
CAASSingapore Limit without approval: 100 Wh; 100–160 Wh with airline approval. — caas.gov.sg 21 Oct 2026
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Related questions

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