Power Banks: Rules and Safe Use
Power banks are the accessory with real rules attached. This page sets out what the FAA and TSA say, shows the mAh-to-Wh arithmetic, explains why a power bank delivers less than its label, and covers safe use. We do not test power banks, so we name no models.
Can I take a power bank on a plane?
Yes, in carry-on baggage only. The FAA says spare (uninstalled) lithium-ion batteries, including power banks and cell phone battery charging cases, must be carried in carry-on baggage only, and the TSA’s lithium battery page says the same for spare batteries. These are the FAA’s rules in brief:
- If a carry-on bag is checked at the gate or at planeside, remove all spare lithium batteries and power banks from it and keep them with you in the cabin.
- Battery terminals must be protected from short circuit, for example by leaving the battery in its retail packaging, taping the terminals, or using a battery case, sleeve, plastic bag or protective pouch.
- Tell the flight crew immediately if a battery or device is overheating, expanding, smoking or burning.
- Damaged or recalled batteries that are likely to create sparks or dangerous heat must not be carried aboard, in carry-on or checked bags, unless the battery has been removed or made safe.
- The TSA adds that the final decision on whether an item goes through the checkpoint rests with the TSA officer.
A phone with its battery installed follows different rules from a spare battery. The FAA says such a device can be checked only if it is completely powered off and protected from accidental activation.
What are the 100 Wh and 160 Wh limits?
The FAA limits rechargeable lithium-ion batteries to 100 Wh per battery, with a larger band that needs airline approval.
| Battery rating | What the FAA says | Source |
|---|---|---|
| 100 Wh or less | Allowed in carry-on. No quantity limit for most batteries, but they must be for the passenger’s own use | FAA |
| 101 to 160 Wh | Needs airline approval, with a limit of two spare batteries per person | FAA |
| More than 160 Wh | Not allowed on passenger aircraft (the FAA names large power banks and power stations) | FAA |
| Any size, spare, in checked bag | Not allowed. Spare power banks are carry-on only | FAA, TSA |
The FAA also says many airlines, domestic and international, set stricter quantity and Wh limits, including how many power banks each passenger may carry regardless of capacity. Check your carrier before you travel.
How do I convert mAh to Wh?
Divide the mAh rating by 1,000 to get amp-hours (Ah), then multiply by the battery voltage; the result is watt-hours. That is the FAA’s method, and it gives the example of a 12-volt battery rated at 8 Ah, which is 96 Wh. The FAA also says newer lithium-ion batteries have the Wh rating marked on them, so look for that first.
Most power banks print only mAh. Wikipedia says lithium-ion cells typically have a nominal voltage of 3.6 or 3.7 V. The table below is our own arithmetic using those two values; it assumes a typical cell, so a Wh figure or voltage printed on your unit takes priority.
| Rated capacity | Amp-hours | Wh at 3.6 V | Wh at 3.7 V |
|---|---|---|---|
| 5,000 mAh | 5 Ah | 18.0 | 18.5 |
| 10,000 mAh | 10 Ah | 36.0 | 37.0 |
| 20,000 mAh | 20 Ah | 72.0 | 74.0 |
| 27,000 mAh | 27 Ah | 97.2 | 99.9 |
| 30,000 mAh | 30 Ah | 108.0 | 111.0 |
Our arithmetic. Working backwards, 100 Wh is about 27,000 to 27,800 mAh at those two voltages, and 160 Wh is about 43,200 to 44,400 mAh. A 30,000 mAh unit would be in the airline-approval band on this arithmetic, which is why the printed Wh rating matters.
Why does a power bank deliver less than its label?
The advertised capacity usually describes the battery inside, not what reaches your phone. Wikipedia says the advertised capacity is in many instances based on the internal cells, while the mAh available at the output depends on the output voltage. Its example is a 3.7 V battery with a 5 V output, where the theoretical mAh is 74% of the battery rating (our check: 3.7 divided by 5 is 0.74).
| Step | Figure | Source |
|---|---|---|
| Advertised capacity of one evaluated power bank | 26,800 mAh | Wikipedia |
| Theoretical capacity at the output | 19,832 mAh | Wikipedia |
| Capacity actually delivered in the evaluation | 15,682 mAh | Wikipedia |
| Delivered, as a share of the advertised figure | About 59% | Our arithmetic: 15,682 / 26,800 |
Wikipedia also says the conversion circuit wastes some energy, and that the average power bank in 2023 transferred around two-thirds (67%) of its battery energy into the device being charged. That is one cited estimate, not a promise about any product. Plan for noticeably fewer phone charges than the label suggests.
How do I use and store a power bank safely?
Treat it as a lithium-ion battery. The FAA says all lithium-ion batteries can overheat and undergo thermal runaway, which can occur without warning if a battery is damaged, overheated, exposed to water, overcharged or improperly packed, or on its own from a manufacturing defect.
| Habit | What the source says | Source |
|---|---|---|
| Stop using a suspect battery | Stop if you notice an odor, change in color, too much heat, change in shape, leaking or odd noises | U.S. Fire Administration |
| Temperature | Store at room temperature when possible. Do not charge below 0 C (32 F) or above 40 C (105 F) | U.S. Fire Administration, citing NFPA |
| Heat and storage | No direct sunlight or hot cars; keep spares away from anything that can burn | U.S. Fire Administration |
| Disposal | Do not put lithium-ion batteries in the trash; recycle them | U.S. Fire Administration |
| Recalls | Check the Consumer Product Safety Commission, maker or seller for recalls | FAA |
How do I choose a power bank?
Start with the rules above, then match the output to your phone. This checklist is ours, built from the sources on this page.
- Read the Wh rating. If you fly, a unit rated at 100 Wh or less avoids the approval step. Use the arithmetic above only when no Wh figure is printed.
- Match the charging standard. Look up your phone in the wattage guide and see USB Power Delivery. A power bank is a charger source, so the same wattage and standard questions apply.
- Buy certified, from a trusted source. The USB-IF says to buy compliant USB products from trusted sources that display certified logos, and the U.S. Fire Administration lists “choose certified products” first. See cable buying safety for why marks can be faked.
- Consider a battery case. The FAA’s rules cover cell phone battery charging cases as well. Wikipedia describes battery cases as small power banks attached to the back of a phone, and says Apple’s 2021 MagSafe Battery Pack has an 11.13 Wh battery, far under 100 Wh. See MagSafe.
Do international flights follow different rules?
They can, because airlines and countries may be stricter than the FAA. The FAA itself tells passengers to check their carrier for specific restrictions. Wikipedia reports that the International Civil Aviation Organization published new power bank guidelines on 27 March 2026, limiting passengers to two and prohibiting recharging power banks during flights. The FAA page we read, last updated 11 August 2026, still lists no quantity limit for most batteries under 100 Wh. We could not open ICAO’s own site, so treat the ICAO detail as a reason to read your airline’s rules, not as a substitute.
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