Start with the bag, not the clothes
Most packing failures start with the wrong bag. For a 10-day trip, use a 40-liter carry-on backpack or a 22 x 14 x 9 inch roller — the standard that clears almost every airline's overhead bin. Weights matter more than dimensions on budget carriers: Ryanair caps cabin bags at 10 kg, while most US airlines don't weigh carry-ons at all. Weigh your packed bag at home on a luggage scale; a 40L bag packed for ten days typically lands between 8 and 11 kg.
The clothing formula: 5-4-3-2-1
Pack five tops, four bottoms, three layers, two pairs of shoes, and one swimsuit or extra outfit. That's 15 clothing items, which fits in a 40L bag with room for toiletries. Choose quick-dry fabrics — merino wool tees cost more upfront ($60–$90) but can be worn three times between washes without smelling. Do laundry once mid-trip at a laundromat ($5–$10) or hotel sink, and you effectively double your wardrobe.
Toiletries: the 3-1-1 rule, decoded
TSA and most international security lines allow liquids in containers of 3.4 oz (100 ml) or less, all inside one quart-sized clear bag. Buy solid shampoo bars ($8–$12) and stick deodorant to cut liquid volume by half. Decant sunscreen into a 100 ml bottle — a full-size 8 oz bottle will be confiscated. Pack a flat, reusable quart bag instead of a flimsy zip-top; it survives dozens of trips.
Tech that earns its space
Bring one universal power adapter with two USB-C ports ($25–$40), one 10,000 mAh power bank (under 100 Wh, so it's flight-legal), and a single 6-foot charging cable. Skip the laptop on trips under a week; a phone handles maps, boarding passes, and bookings. If you need a computer, a 13-inch laptop adds about 1.3 kg — worth it only if you'll work more than an hour a day.
What to leave home
Leave the 'just in case' items: the second jacket, the dress shoes, the full-size hairdryer (hotels have them), and the paper guidebook. Also skip travel-sized everything — one 100 ml bottle of multi-use soap beats five tiny bottles. If you haven't used an item on your last three trips, it doesn't belong in the bag.
The 20-minute repack test
Two weeks before departure, pack the bag fully, then unpack and repack it in under 20 minutes. If it takes longer, you have too much. Photograph the final layout on your phone so you can replicate it on the return leg. Travelers who do this report checking fewer bags and losing fewer items — and the $35–$50 per-checked-bag fee stays in their pocket.