TL;DRA carry-on-only trip removes bag fees, eliminates lost-luggage risk, and saves 30–60 minutes at every airport. With merino layers and laundry every 4–5 days, three weeks fits comfortably in a 40-liter bag.
Every traveler who switches to carry-on-only says the same thing: they wish they'd done it sooner. The reasons aren't really about packing — they're about everything that goes wrong with checked bags. You skip the bag-drop line. You skip the carousel wait. You can take a delayed flight on the next available aircraft without your luggage getting separated from you. You can leave the airport for a same-day connection through a different airport without paying transfer fees. And you eliminate the 1-in-150 chance per flight that your bag goes missing — a number that rises to 1-in-30 on connecting itineraries.
None of this requires deprivation. A 40-liter carry-on plus a small personal item is enough for 3 weeks anywhere. The system is laundry, not more clothes.
The packing system that scales to any length
The math doesn't change once you accept that you'll wash clothes every 4–5 days. You pack for one wash cycle, not for the whole trip:
- 4 shirts — 2 merino t-shirts, 2 button-downs (one can be linen for warm climates). Merino wool resists odor for multiple wears, dries overnight, and doesn't wrinkle.
- 2 pairs of pants — one travel-friendly (synthetic, dries fast), one nicer. Plus shorts if the climate calls for them.
- 5–7 underwear and socks — quick-dry synthetics so you can rinse and hang overnight if the laundry day slips.
- 1 light layer — packable down jacket or fleece, depending on coldest expected temperature.
- 2 pairs of shoes max — one walking, one nicer or sandal. Heaviest pair worn on the plane.
Toiletries in containers no larger than 100ml (3.4 oz) total, packed in a 1-quart resealable bag per TSA's 3-1-1 rule. Almost everything else (sunscreen, shampoo, toothpaste) you can buy at the destination if you'd rather not pack it.
The laundry math
Three options in increasing order of convenience and cost:
- Sink wash — bring a small tube of laundry soap (Sea to Summit packets work). Wash in the hotel sink, roll in a towel to remove water, hang overnight. Underwear and merino dry by morning; jeans don't.
- Laundromat — most cities outside the US have neighborhood laundromats charging $4–8 per load. Self-service or drop-off.
- Hotel/Airbnb laundry service — usually $1–3 per piece, fastest but most expensive. Worth it when you have a one-night stop and don't want to spend it in a laundromat.
Wash mid-trip whether you "need" to or not. You always need fresh clothes by day 5 even if you packed light enough that nothing smells yet.
Common pitfalls
The "just-in-case" overpacking instinct is the killer. You will not need a third pair of dress shoes. You will not need the extra jacket. You will not need the second set of toiletries. Trust the system: anything you forget can be bought at the destination for less than the bag fee.
Bottom line
Carry-on-only is not a skill, it's a decision. Once you commit, the packing follows. The freedom is real: shorter lines, no lost-bag risk, smoother connections, and the option to walk out of an airport at the end of a long-haul flight without waiting for a carousel. After one trip, the checked bag will feel like the strange choice.
