The short answer: pack anything you can't afford to lose, can't replace, or can't be without — valuables, medications, electronics, spare batteries and a change of clothes — in your carry-on, and put bulky, heavy or restricted items — large liquids, sharp objects, anything over the 3-1-1 limit — in your checked bag. The reason isn't just convenience: some items are legally required to stay in the cabin, and checked bags occasionally get delayed or lost.
Below is how to split your packing so nothing gets confiscated at security, stranded on a carousel, or turned away at the gate.
1. What must go in your carry-on
Some things belong in the cabin because rules require it, and others simply because you can't risk losing them. Keep these with you:
- Power banks and spare lithium batteries. Airlines require these in the cabin, not in checked bags, for fire-safety reasons — spare/loose lithium batteries and portable chargers are generally banned from checked luggage. Check watt-hour limits with your airline.
- Valuables and electronics. Laptop, camera, phone, jewelry, cash — anything expensive or irreplaceable should never be checked.
- Medications. Keep prescriptions and essential medicine on you in case a checked bag is delayed; carry them in their original packaging where possible.
- Travel documents and keys. Passport, boarding pass, wallet, house/car keys.
- A change of clothes and basics. If your checked bag goes missing, a spare outfit and small toiletries kit save the first day of your trip.
2. What should go in your checked bag
Checked bags exist for the things security won't let through the cabin or that are simply too big for a carry-on.
- Large liquids. Full-size toiletries, sunscreen and anything over the 3-1-1 limit (see the TSA liquids rule) belong in checked luggage.
- Sharp items. Full-size knives, scissors, razors with exposed blades and most tools are typically not allowed in the cabin.
- Bulky and heavy gear. Extra shoes, hiking equipment, bottles of anything — put weight and volume in the hold.
- Aerosols and certain sporting goods within airline quantity limits, along with anything you won't need until you land.
One caution: never put spare lithium batteries, power banks, or e-cigarettes/vapes in a checked bag — those must travel in the cabin.
3. Carry-on vs checked at a glance
| Item | Carry-on | Checked |
|---|---|---|
| Power banks / spare lithium batteries | Required | Not allowed |
| Laptop, camera, jewelry, cash | Best here | Avoid |
| Medications | Best here | Risky if delayed |
| Liquids over 3.4 oz / 100 ml | Not allowed | Yes |
| Knives, scissors, tools | Usually not allowed | Yes (within limits) |
| Full-size toiletries | No | Yes |
| Change of clothes | Smart backup | Fine |
Rules vary by airline and country, so treat this as a starting point and confirm anything unusual with your airline and the security authority you're flying from.
4. Fees, time and the trade-offs
Choosing between carry-on only and checking a bag isn't just about space:
- Fees. Many airlines charge for checked bags, especially on cheaper fares; carry-on only can save money as well as time.
- Time. Checking a bag means arriving earlier for bag drop and waiting at the carousel on the other end; carry-on only lets you walk straight off the plane.
- Gate-check risk. On full flights, carry-ons are sometimes gate-checked when overhead space runs out — keep essentials and valuables in a personal item you keep at your seat, just in case.
- Weight limits vary. Both carry-on and checked allowances differ by airline, fare and route, and some carriers weigh carry-ons. Check your specific ticket before you pack.