Lithium batteries are the one packing rule where getting it backwards can be dangerous, not just inconvenient. The core principle is the opposite of what most people assume: spare lithium batteries and power banks must fly in your carry-on, never in checked baggage. A checked bag rides in a cargo hold no one can reach in flight, so a battery fire there is far more serious than one in the cabin. Everything else about the rule comes down to a single number on the battery — its capacity in watt-hours (Wh).
Last checked: July 2026 — sourced against FAA PackSafe battery guidance and TSA “What Can I Bring?”. Airline per-passenger caps shifted through 2025-2026; re-verify before you fly.
The verdict, in one line
Carry-on: yes for power banks and spare batteries — this is the only place they are allowed. Checked bag: no for spare lithium batteries and power banks; they are prohibited in the hold. Devices with an installed battery (a laptop, phone, or camera) may go in checked baggage if the airline permits, but the spare cells that power them may not.
Watt-hours: the number that decides everything
For lithium-ion batteries (the rechargeable kind in phones, laptops, and power banks), the limit is measured in watt-hours. Many batteries print the Wh rating directly on the casing. If yours only shows milliamp-hours (mAh) and volts (V), convert it:
Wh = (mAh ÷ 1000) × V — for example, a 20,000 mAh power bank at 3.7 V is (20000 ÷ 1000) × 3.7 = 74 Wh, comfortably under the free limit.
| Capacity | Carry-on | Checked | Conditions |
|---|---|---|---|
| 100 Wh or less | Allowed | Prohibited (spares) | No airline approval needed; carry as many as are for personal use |
| 101–160 Wh | Allowed with approval | Prohibited | Airline approval required; limit of 2 spare batteries per passenger |
| Over 160 Wh | Banned | Banned | Not permitted on passenger aircraft at all |
To put those numbers in context: nearly every phone, tablet, and standard power bank sits under 100 Wh. Most laptops are also under 100 Wh, though large workstation and gaming laptops can approach the 101–160 Wh band. Batteries above 160 Wh are typically for professional film gear, e-bikes, and mobility scooters, and are handled under separate rules.
Lithium-metal batteries: measured in grams, not watt-hours
Non-rechargeable lithium-metal batteries — the coin cells and AA-style lithium batteries in watches, key fobs, cameras, and some medical devices — are rated by lithium content in grams instead of watt-hours. The consumer limit is 2 grams of lithium per battery, which covers essentially all household lithium-metal cells. Like their rechargeable cousins, spare lithium-metal batteries must travel in the carry-on, never in checked baggage.
How to pack them safely
- Prevent short circuits. Keep spare batteries in their original packaging, or tape over the terminals, or put each in its own plastic bag or battery case. Loose batteries rubbing against keys or coins are the main fire risk.
- Keep them accessible. Newer airline rules increasingly require power banks to be within reach — not in an overhead bin — so a fire can be dealt with quickly. Several Asian carriers now ban using or charging power banks in flight entirely.
- Do not check them. If you are gate-checking a carry-on because the bins are full, remove every power bank and spare battery first and keep them on your person.
The layer TSA.gov skips: airline-by-airline caps
This is where the rule genuinely varies, and where it changed fast in 2025 and 2026 after several onboard battery incidents. The FAA sets the Wh thresholds, but individual airlines add their own limits on top — some cap the total number of spare batteries, some require power banks to stay visible rather than in a bag, and several international carriers (particularly in South Korea, Taiwan, Hong Kong, and mainland China) now prohibit charging devices from a power bank during the flight. Because these caps are still shifting, do not trust a number you read months ago: check your specific airline’s dangerous-goods or restricted-items page shortly before you travel. Vapes and e-cigarettes follow this same carry-on-only battery logic — never in checked baggage, never used or charged onboard.
The final word
Keep spare lithium under 100 Wh in your carry-on with the terminals protected and you will clear security without trouble. But the TSA officer, and separately the airline, can refuse any battery they judge unsafe or non-compliant — and for the 101–160 Wh band, the airline’s approval is not optional. When a battery’s rating is unmarked or unreadable, assume it is not allowed until you can confirm otherwise.
Related rules: the 3-1-1 liquids rule · sharp objects & tools · flying with medication
FAQ
Can I put a power bank in my checked suitcase?
No. Power banks and all spare lithium batteries are prohibited in checked baggage and must fly in the cabin, where a fire can be reached and controlled. This applies even if the bag is gate-checked.
How do I know my power bank’s watt-hours?
Look for a “Wh” figure printed on the casing. If it only lists mAh and volts, calculate: (mAh ÷ 1000) × V = Wh. A 20,000 mAh bank at 3.7 V is 74 Wh, under the 100 Wh free limit.
Is there a limit on how many power banks I can bring?
For batteries at or under 100 Wh there is no fixed federal number beyond “personal use,” but many airlines set their own cap. Batteries in the 101–160 Wh range are limited to two per passenger and need airline approval.
Can I use or charge my power bank during the flight?
US rules require it to be accessible, and a growing number of international airlines now ban using or charging power banks in flight altogether. Check your carrier’s restricted-items page before you fly.
What about the lithium batteries in my devices, not spares?
Devices with installed batteries — laptops, phones, cameras — may go in checked bags if the airline allows, but it is safer to keep them in the cabin. Only loose spare batteries are strictly barred from checked luggage.