What to Pack Calculator

How the packing list is built

Most packing advice is a flat checklist that ignores the two things that change what you need: how long you are gone, and whether you can wash clothes while you are there. This calculator starts from those two inputs and works out quantities instead of handing you a generic list.

The core rule is simple. Without laundry, you need one of each worn item per day, plus a small buffer. With laundry, you plan for about half the trip and wash once in the middle, which cuts your clothing roughly in half. A third input, the trip type, adds the specific extras that a beach, ski, business or camping trip needs on top of the basics.

• Tops: one per day without laundry, or about half that with a mid-trip wash
• Bottoms: one pair per two to three days, since pants get re-worn
• Underwear and socks: one per day plus two spares, always
• Extras: driven by trip type, swimsuit, coat, suit, or hiking gear

The quantities line up with the practical limits the TSA carry-on rules and the US State Department's travel guidance assume, so the list you build is one you can fly with.

Worked example: a 7-day trip with laundry

You are flying to a warm city for seven days and your hotel has a guest laundry. Because you can wash once mid-trip, you plan for four days of clothing and repeat the rest.

• Tops: 4
• Bottoms: 3
• Underwear: 8 (one per day plus one spare)
• Socks: 8
• Swimsuit: 1, plus a hat and sunglasses for the trip type

That is 23 clothing items, which fits a 40-liter carry-on with room for a toiletry bag and a pair of sandals. Compare that to the no-laundry version of the same trip: seven tops, five bottoms, nine underwear and nine socks, about 30 items, which pushes you into a checked bag.

The saving is real. One load of laundry, usually under $10 at a hotel or a laundromat, removes roughly a quarter of your packing and keeps you in a carry-on, which on many airlines saves a $35 checked-bag fee each way.

Worked example: a 14-day trip without laundry

Now imagine a two-week road trip through national parks with no laundry access. Everything is one per day plus spares, but the layers change the total.

• Tops: 14 (one per day)
• Bottoms: 8 (one per two days)
• Underwear: 16 (14 plus two spares)
• Socks: 16
• Extras: one fleece, one rain shell, one hat, hiking boots, two water bottles

That is 54 clothing items plus gear, clearly a checked bag or two. The honest math is that two weeks of unwashable clothing cannot fit a carry-on, so either build in a laundromat stop every four days or plan to check a bag.

If you add one laundry stop at day seven, the clothing count drops to about 32 items: seven tops, five bottoms, ten underwear and ten socks. That is the single biggest packing decision you can make, and it is exactly what the laundry toggle in the calculator is there to show you.

Packing quantities by trip length

Quick reference for a warm-weather trip, with and without laundry access:

Cold-weather trips shift the balance: fewer tops, more layers and bulkier footwear, so add roughly 30% to the volume even when the item count looks similar.

The extras that trip type adds

The clothing counts are the same whether you are going to Miami or Minneapolis, but the extras are not. That is why the trip type matters. A beach trip needs two swimsuits so one is always dry, a cover-up, flip-flops, a wide-brim hat and reef-safe sunscreen. A cold-weather trip needs thermal base layers, a fleece, a waterproof shell, gloves, a hat and a scarf, plus boots you can walk in.

A business trip trades swimwear for one suit, two dress shirts, dress shoes and a small steamer or wrinkle-release spray. A camping or outdoors trip swaps most clothing for gear: a headlamp, a first-aid kit, a water filter, a rain jacket and a knife. City sightseeing sits in the middle, comfortable walking shoes, one nicer outfit for dinner, and a small daypack.

Two items are universal and easy to forget: a refillable water bottle and a small power bank. On a full day out, both matter more than a third pair of shoes. And whatever the trip, check the FAA's packing-safe rules before you fly if you are bringing a power bank, which must go in your carry-on rather than a checked bag.

Packing smarter, not heavier

Once you have the right quantities, how you pack decides whether it fits. Roll soft items like t-shirts and underwear, fold structured ones like collared shirts, and stuff socks inside shoes to reclaim dead space. Put the heaviest items at the bottom of a backpack, near your back, so it carries comfortably.

Use packing cubes for categories, not for outfits, a cube for tops, one for bottoms, one for underwear and socks. It keeps a small bag organized and makes an airport security search quick to repack. Wear your bulkiest items on the plane: boots, coat and jeans should not be in the bag at all.

Finally, leave about 10% of the bag empty. Almost every trip ends with something you bought, and having nowhere to put it is how a tidy carry-on becomes an awkward extra shopping bag at the gate. If you are weighing a bag against an airline limit, the TSA's what-can-I-bring list answers the item-by-item questions that come up at security.

Weigh the bag before you leave home. A bathroom scale works fine: stand on it holding the bag, then stand on it alone, and subtract. Most international carry-on limits are 22 pounds (10 kg), and a week of clothing plus a toiletry bag lands right around there, knowing the number at your kitchen table is a lot cheaper than discovering it at the gate.