One bag, one week, and nothing you don't use

The whole thing turns on one decision, and it isn't which bag you buy. It's whether you're washing anything mid-trip.

Answer that and the list writes itself. Say yes, and four days of clothes covers a fortnight. Say no, and seven days of clothes is seven days of clothes, plus the weight of every wet towel and worn shirt you're now carrying home. Most people never make the decision. They just pack "a week," end up with eleven shirts for seven days, and wonder why the bag won't close.

So decide. Then pack to the decision.

The bag

Something in the 35 to 40 litre range does a week comfortably. Below 30 and you're doing real editing. Above 45 and you'll fill it, because everybody fills whatever they carry.

Check your airline's stated carry-on dimensions before you buy anything. The common US domestic allowance is roughly 22 by 14 by 9 inches, and plenty of bags are built exactly to it. European budget carriers are meaner, and some of them will make you put the bag in the metal frame at the gate. A bag that fits one and not the other is a bag you'll fight with.

Two features matter more than the marketing does. A clamshell opening, so the thing lies flat and you can see everything at once, rather than digging down a tube. And a proper padded harness if you're carrying it more than ten minutes. A shoulder strap on 25 pounds is a punishment.

Everything else is preference. Water bottle pockets are nice. Seventeen internal organizer sleeves are not, because you'll forget which one has the charger.

The clothes, actually

For a week in temperate weather, doing laundry once:

• Four shirts or tees
• One button-down or overshirt that works for dinner
• Two pairs of trousers or one plus one pair of shorts
• One sweater or midlayer
• One packable rain shell
• Four pairs of underwear, four pairs of socks
• Sleepwear, if you use it
• Swim shorts, if there's water

That's it. You'll wear one full outfit on the travel day, so what's in the bag is less than the list looks.

The reason this works is repetition. Pick one color for your trousers and one for your shoes, and make every top work with both. Navy, olive, gray, white. If you have to think about whether two items go together, one of them stays home.

Merino wool earns its price here for socks and one shirt. It'll go three or four wears without smelling, which is the entire point of one-bag travel. Cotton is comfortable and it holds odor, and it takes a full day to dry. Synthetic dries in two hours and some of it turns on you by hour six. Mix accordingly.

Shoes are the real problem

Shoes are bulky, heavy, and the thing people get wrong. Two pairs. Total. You wear the heavier ones.

One pair should walk fifteen miles without complaint and still look acceptable in a restaurant. Leather sneakers, a plain low-profile trainer, a decent chukka. The second pair is whatever your trip specifically demands — sandals for a beach, something dressier for a wedding, trail shoes for hills.

If your trip doesn't specifically demand a second pair, don't pack one. Nobody at your destination is auditing your footwear rotation.

Stuff socks and chargers inside the packed pair. It's free volume and it keeps the shoe in shape.

Doing the laundry, for real

This is the part people skip, and then the system collapses.

Sink washing works and takes about ten minutes. Plug the sink, warm water, a small amount of soap, agitate, rinse until the water runs clear. Then the towel trick: lay the wet garment flat on a hotel towel, roll the towel up tight, and stand on it. That pulls out most of the water. Hang it overnight and it's dry by morning. Merino and synthetics will be. Heavy cotton might not be, which is another reason to limit it.

Bring a bar of laundry soap or a small tube of liquid. Not a whole bottle. A flat rubber sink stopper weighs almost nothing and solves the hotel sink that won't hold water.

Or use a launderette. In most cities, a wash and dry runs under an hour and costs less than a couple of coffees. Build it into a slow afternoon on day four. It's an hour you'd have spent scrolling anyway, and it's how locals see their own city.

Liquids, and the bag within the bag

One clear quart-sized bag, and it should live permanently packed. That's the trick. You don't assemble toiletries per trip, you maintain a kit that's always ready and you top it up when you get home.

Solid versions save space and don't count against liquid limits. Bar soap, solid deodorant, toothpaste tabs if you like them. Buy sunscreen at the destination rather than surrendering half your liquids allowance to it.

Leave the hotel-provided stuff out of your calculations only if you know what the place provides. A budget guesthouse may give you nothing.

If you take prescription medication, keep it in your carry-on in its labeled container, and bring enough to cover delays. Talk to your pharmacist before a long trip about what crossing time zones does to a dosing schedule — that's their job, not an internet article's.

Cubes, rolling, and the compression argument

Packing cubes don't create space. They organize it, and organization is worth a lot when you're living out of the bag for seven days. Two or three cubes, sorted by category rather than by day. Tops in one, bottoms and layers in another, small items in the third.

Compression cubes do create space, by squeezing air out. They also create a dense brick that's heavier than it looks, and they encourage you to pack more, which defeats the exercise.

Rolling beats folding for tees and knits. Folding beats rolling for a button-down you want to wear to dinner. Do both.

What the gear-obsessed version gets wrong

The one-bag world online is mostly about the bag. Strap routing, fabric denier, a hundred photographs of the same neatly arranged flat-lay on a wooden floor. None of that is travel. It's shopping.

The people who genuinely travel light own boring bags and wear the same four shirts. They're not optimizing. They've just stopped bringing the third jacket "in case."

The "in case" items are where the weight lives. In case it's formal. In case it rains twice. In case I want to run. Pick the ones that are actually likely and let the rest go. Almost everywhere you're going sells socks.

With a family

Kids can't carry their own week, and you shouldn't try to make them. But the principle scales: one shared toiletry kit instead of four, one laundry night instead of packing seven days each, and a strict two-pairs-of-shoes rule enforced by a parent, not negotiated.

Give each child one small bag they pack themselves, with a written list you check. They'll forget something the first trip. That's the lesson, and it's cheaper to learn at eight than at twenty-eight.

Pack a spare outfit for the youngest in your bag, not theirs. You know why.

The night before

Lay it all out on the bed. Then remove three things.

You won't miss them. You never do.

The real payoff isn't the packing. It's landing, walking past three hundred people watching a stationary carousel, and being outside in a taxi before the first suitcase drops.