The short answer
Pick carry-on only for trips up to about a week when you can keep toiletries under 3.4 oz: it’s free on standard fares at major airlines and nothing gets lost. Check a bag when you need full-size liquids, sharp tools, or more than one carry-on’s worth of clothes, and budget about $45–$50 each way.
Carry-on vs checked, side by side
| Carry-on | Checked bag | |
|---|---|---|
| Size limit | 22 × 14 × 9 in on most US airlines | 62 linear in (158 cm) |
| Weight limit | Usually none in the US; 7–10 kg abroad | 50 lb (23 kg) in economy |
| Cost (major US airlines) | Free on standard fares | About $45–$50 for the first bag, each way |
| Liquids | 3.4 oz (100 ml) containers, one quart bag | Full-size toiletries allowed |
| Sharp items & tools | Mostly not allowed | Allowed |
| Batteries & vapes | Required here | Not allowed |
| Risk | Gate-checked if bins are full | Delayed or lost bags |
| On arrival | Walk straight out | Wait at the carousel |
When a carry-on wins
- Short trips and business travel.
- Tight connections, where checked bags miss the transfer.
- Budget airlines, where a carry-on bought at booking can cost less than a checked bag.
When to check a bag
- Trips longer than a week, cold weather or formal clothes.
- Full-size shampoo, sunscreen, wine or anything else over 3.4 oz.
- Knives, tools, sports gear or anything TSA won’t allow in the cabin.
- Traveling with kids, when you’d rather not haul bags through the airport.
Frequently asked questions
Is it cheaper to carry on or check a bag?
On major US airlines a carry-on is free on standard fares, so carry-on is cheaper. On budget airlines a carry-on and a checked bag can cost about the same; compare when you book.
Can I check my carry-on bag?
Yes. Any bag within the checked limits can be checked, and the normal checked bag fee applies at the counter. Gate-checking a carry-on when bins are full is free on major airlines.