You can bring a power bank on a plane up to 100 watt-hours without special approval, between 101 and 160 watt-hours only if your airline says yes, and you can’t bring anything over 160 watt-hours at all. Every spare lithium battery, including power banks, has to ride with you in the cabin, never in a checked bag.
That limit is based on energy, not the big milliamp number on the box, so two packs that both say 20000mAh can land on different sides of the rule. The fix is quick: read the mAh and voltage printed on the pack and turn it into watt-hours with Wh = (mAh ÷ 1000) × V. The official FAA PackSafe Wh bands show 0–100Wh allowed, 101–160Wh needs carrier approval, and over 160Wh is forbidden, while the TSA power bank carry-on rule confirms carry-on yes, checked no — and three tiny checks on the label tell you in 30 seconds whether it flies without calling the airline.
Why the airline limit is in watt-hours, not milliamp-hours
Airlines don’t measure battery risk by how much charge a pack claims. They measure it by total energy, because energy is what turns into heat in a failure.
Milliamp-hours counts charge. Watt-hours counts energy. The difference is voltage. Watt-hours = volts × amp-hours, and since most labels give you milliamp-hours, you first divide by 1000 to get amp-hours, so Wh = V × (mAh ÷ 1000). That matters because marketers print mAh at the internal cell voltage, usually 3.6V to 3.85V, while the USB port boosts output to 5V. Two packs both labeled 20000mAh at different nominal voltages hold different energy.
The FAA PackSafe Wh bands make that the rule: 0–100Wh allowed in carry-on without approval, 101–160Wh allowed only with carrier approval, over 160Wh forbidden on passenger aircraft. The FAA lithium battery approval rule repeats that 100Wh to 160Wh needs airline approval and anything over 160Wh is prohibited, and spare lithium batteries including power banks must never go in checked bags. If voltage changes, the same mAh can flip bands.
Interactive calculator showing how same mAh at different nominal voltages produces different Wh and flips between FAA bands
That mechanism explains why the FAA Wh calculation formula says to calculate watt hours by multiplying voltage by amp hours and to divide mAh by 1000 first to get Ah. It’s not a marketing conversion. It’s the energy number officers use.
How to calculate watt-hours from mAh before you pack
You don’t need the listing. You need the fine print on the pack itself.
Try this before you buy: flip your power bank over and read the tiny embossed label. Look for three things — mAh, V, and Wh. If Wh is printed, use that number directly. Officers trust printed Wh more than mental math.
If Wh is missing, do this 30-second worksheet:
Step 1: Find mAh and nominal voltage
Locate mAh printed on housing, usually 10000mAh, 20000mAh, 26800mAh, or 30000mAh. Right next to it look for nominal voltage, typically 3.6V or 3.7V, sometimes 3.85V for Li-polymer packs. That’s the cell voltage you must use, not the 5V USB output.
Step 2: Apply the formula
Wh = (mAh ÷ 1000) × V. So Wh = (mAh × V) ÷ 1000. For example, Wh to mAh conversion formula shows 10000mAh × 3.7V ÷ 1000 = 37Wh. Same math at other sizes: 10000mAh at 3.7V is about 37Wh, 20000mAh at 3.7V is about 74Wh, 26800mAh at 3.7V is about 99.2Wh, 30000mAh at 3.7V is about 111Wh. Those four numbers are estimated using typical nominal voltage — your exact pack’s label is the source of truth.
Step 3: Map to FAA band
If your result is 0–100Wh, you can bring it without airline approval. If it’s 101–160Wh, you need approval and most airlines limit you to two spares. Over 160Wh you can’t bring it. If the label already shows Wh, don’t recalculate — use the printed Wh.
An edge case trips people: a pack that lists 20000mAh at 5V output rating would calculate as 100Wh if you misuse 5V. The correct cell voltage 3.7V gives 74Wh. Always use the nominal cell voltage, because that’s how the FAA Wh calculation formula defines energy — volts times amp-hours, with mAh divided by 1000.
Can you bring a 20000mAh power bank on a plane?
Yes, in most cases, but the yes depends on voltage, not just mAh.
A typical 20000mAh pack at 3.7V is 74Wh, well under the 100Wh carry-on threshold, so it’s allowed without airline approval. At 3.6V that’s 72Wh. At 3.85V Li-poly it’s about 77Wh. All three are still in the 0–100Wh band, which is why most 20000mAh packs fly fine.
The confusion comes when listings mix output rating with cell rating. If a product page only shows 20000mAh without voltage or Wh, you can’t know from mAh alone whether it’s 74Wh or closer to 100Wh. That’s why you need the label. And even under 100Wh, some airlines set their own cap — for example, Chinese carriers have required a maximum of two power banks per passenger.
Table comparing common mAh capacities at 3.7V nominal to calculated Wh and resulting FAA carry-on bands
If your pack is 20000mAh but the fine print says 3.85V or lists Wh as 77Wh, you’re still under 100Wh, so it fits the TSA limit of 100Wh per battery that many secondary explainers cite. Keep that label clean — that’s what an officer will actually read.
What TSA and FAA actually say about carry-on vs checked bags
Both agencies say the same thing in different words: power banks are spare lithium batteries, not accessories.
The TSA carry-on yes checked no page lists power banks as carry-on yes, checked no. FAA guidance confirms spare batteries must be carried on, not checked, resources page says spare lithium-ion batteries and power banks must be carried on.
The reason is fire containment. A battery fire in the cabin can be seen, smothered with a fire containment bag, and handled by crew. In the cargo hold it can’t be reached. That’s why the rule bans all spare lithium in checked bags, even if the bag is small.
At security, check that the label shows Wh or mAh and V clearly readable; if not, print the spec sheet as a backup. If your checked bag gets gate-checked at the jet bridge, you must remove power banks first and carry them on. For protection, keep terminals covered — use original retail packaging, tape over exposed contacts, a case, or a separate plastic bag — the same method FAA recommends for dry-cell spares and a good practice for power banks too.
Do you need airline approval for a power bank?
It depends on watt-hours, not whether it fits in your palm.
The FAA defines three bands. 0–100Wh is allowed without approval for personal use. There is no FAA quantity limit, but airlines can set their own — IATA guidance suggests up to 20 spares at or under 100Wh for reference, while many airlines enforce two power banks max. 101–160Wh is allowed only with airline approval and limited to two spare batteries per passenger. Over 160Wh is forbidden on passenger aircraft. Those three bands come straight from the FAA’s published Wh tiers and the 101-160Wh approval blog that repeats the 100Wh to 160Wh approval requirement and the over 160Wh prohibition.
How to get approval is simple: contact the airline before the flight, show the Wh label at the counter, and bring documentation. If Wh is printed on the device, officers use that. If not, they may ask for mAh and voltage to calculate it, and if they can’t verify, they can refuse it. That’s where the confiscation for missing Wh risk comes from — unknown Wh can mean confiscation even under 100Wh.
Flowchart decision tool showing allowed, approval needed, or forbidden outcomes based on Wh and bag placement
International rules can be stricter. Some regions require a China 3C certification mark for power banks, for example. For US flights, FAA and TSA are your binding reference.
Why airport confiscation happens even under 100Wh
Confiscation isn’t only for big packs. Officers also confiscate when they can’t verify what a pack is.
Three triggers come up most. First, unreadable or missing label — no Wh, no mAh/V, or faded print that can’t be read at the tray. Second, physical damage — swelling, cracked case, exposed terminals, or a pack that feels hot. Third, the officer’s final discretion clause — TSA notes officers make the final decision at the checkpoint.
Traveler forums show even a ~67Wh pack can be taken at Heathrow if it has no marking at all. That’s why confiscation for unknown Wh matters: if you don’t know the Wh rating beforehand, it could be confiscated, and missing label confiscation notes that power banks must be clearly labeled with capacity for verification and may be confiscated without it.
Best practice to avoid it is boring but works. Keep original labeling clean. Carry the pack in an easy-access pouch, not buried. If over 100Wh, declare it. Insulate terminals. Don’t use or charge the power bank on the plane — charging can trigger the airline’s in-flight use ban.
The UN38.3 marking check most listings skip
UN38.3 isn’t a quality badge. It’s transport testing.
UN38.3 is the UN transport testing standard for lithium batteries to ensure they survive altitude, vibration, thermal shock, and short-circuit testing. UN38.3 transport testing explains it ensures batteries are safe for transport by testing under extreme conditions and is required for air freight.
For travelers, the check is practical. Before committing, look for UN38.3 in the spec sheet or manual and for Wh printed on the device itself. The mark isn’t always printed on the housing, but a proper test summary should exist in documentation. Absence itself is a practical flag — a low-cost pack without UN38.3 documentation is more likely to be questioned, because it suggests the pack wasn’t built for air transport in the first place.
Before buying for travel, look for UN38.3 in spec sheet or manual and for Wh printed on device itself — that’s the fastest way to separate travel-ready packs from ones that may get stopped.
The last check: your pre-flight power bank checklist
Use this worksheet at the packing table. Complete one row per power bank before you zip the bag.
Checklist showing five verification steps from label reading to Wh calculation to bag placement
Keep a printed copy with your boarding pass if your pack is near 100Wh. Officers trust a clean printed Wh label and a spec sheet more than mental math at a busy lane.
The last check
Before you zip your bag, read the Wh number — or calculate it from mAh and nominal voltage — and check which FAA band it falls in. That one number tells you whether you need airline approval, whether you must keep it in carry-on, and whether a missing label alone could get it taken. If it’s over 160Wh or the label is unreadable and you can’t prove its Wh, leave it home — a power bank left behind is cheaper than one confiscated at the checkpoint.
Frequently Asked Questions
What is the TSA mAh limit for power banks?
TSA doesn’t set a mAh limit. It uses watt-hours, with 0–100Wh allowed without approval under FAA rules. About 27000mAh at 3.7V is roughly 100Wh, but voltage changes that math.
Can you bring a 30000mAh power bank on a plane?
A 30000mAh pack at 3.7V is 111Wh, so it falls in 101–160Wh and requires airline approval with a max of two spares. At 3.6V it’s 108Wh, same band. Bring documentation and get approval before you fly — the 30000mAh-class pack is exactly the kind that needs it.
Is a power bank allowed in checked luggage?
No. Power banks are spare lithium batteries and are prohibited in checked luggage. They must be in carry-on per TSA guidance — spare batteries are never allowed in checked bags. If your bag is gate-checked, remove them first.
How do you calculate watt-hours from mAh when the label shows only mAh?
Use Wh = (mAh ÷ 1000) × V, where V is nominal voltage printed on the pack, typically 3.6–3.85V. If Wh is already printed, use that number — officers trust printed Wh. The formula comes from the FAA’s own Wh calculation guidance.
