How Do You Work Out Power Bank Wh for a Flight?

How Do You Work Out Power Bank Wh for a Flight?

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Multiply capacity by voltage, divide by 1,000, and compare the answer with the 100 Wh and 160 Wh limits.

Published October 25, 2026 · 3 min read · Topic: Travel & Airline Rules · Travel rules

Typical situation

Your power bank says 20,000 mAh. The airline rules you found talk about watt-hours, and you are not sure whether the bag in your hand is allowed on board.

Main answer · berabags Editorial Team · Safety view

Convert the label to watt-hours, then compare. Watt-hours (Wh) = capacity in amp-hours × voltage. For a power bank labelled in mAh, multiply the mAh by the voltage, then divide by 1,000. Many banks use cells rated at about 3.6 to 3.7 V, so 20,000 mAh at 3.7 V is 74 Wh. A 27,000 mAh bank at 3.7 V works out to about 100 Wh, right at the line. When the case prints a Wh figure, use that and skip the sum.

What the limits say

The FAA’s PackSafe guidance for spare lithium-ion batteries, which includes power banks, is:

  • Spare batteries and power banks go in carry-on baggage, not in checked baggage.
  • Up to 100 Wh is generally allowed.
  • 101 to 160 Wh needs airline approval, and the FAA limits you to two spares of that size.
  • Over 160 Wh is not allowed on a passenger flight.
  • Protect the terminals from short circuits, for example in the original packaging, a battery case or with tape over exposed contacts.

Steps before you leave home

  1. Find the Wh figure on the case, or do the sum above.
  2. If it is over 100 Wh, ask the airline for approval before you travel.
  3. Put the bank in your carry-on, with the terminals protected.
  4. If your carry-on is gate-checked, take the bank out and keep it with you.
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Where this answer stops

Airlines can set rules stricter than the FAA’s, including on how many banks you can carry or use in flight. Check your airline’s page and the rules at your departure airport. This is general guidance, not a ruling on any particular bank.

Sources and further reading

Three more perspectives

berabags Editorial Team · Selection view

If you travel often, look for a power bank with the watt-hour figure printed on the case. It saves you doing the sum at the gate, and a clear marking is easier for an officer to read. A bank that only shows mAh leaves you to prove the conversion.

berabags Editorial Team · Maintenance view

A bank that is warm, swollen or damaged should not travel. Keep terminals covered, for example in a case or with tape over exposed contacts, and keep the bank where you can reach it, not buried under other items. Do not charge it under a pillow or blanket.

berabags Editorial Team · Purchasing view

Before buying a large bank for travel, check the Wh figure against the airline limits rather than the mAh headline. A bank that sits just under 100 Wh leaves little room for a rounding difference. A slightly smaller one is easier to carry on every airline.

Independent and unofficial. berabags is an independent editorial site. It is not affiliated with, endorsed by or sponsored by any bag brand, retailer, airline or agency named on this page. This page contains no affiliate links; if berabags adds any in future they will be labelled. Rules and policies change, so check the linked source before you act. This is general information, not legal, medical or professional advice.

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