Carry-On Only Packing: Travel Light Without Forgetting Essentials

I've run the last 40-odd trips carry-on only, including a 16-day loop through Japan and a two-week work swing through Lisbon, Berlin, and London. Nothing lost, nothing missed, no $75 checked-bag surprises at the Ryanair gate. Here's the system that actually holds up — what to pack, what to skip, and the small rules that keep it under the sizer every time.

Know the actual size and weight limits (they're not all 22x14x9)

The single biggest reason people get pinged at the gate is assuming every airline uses the US standard of 22 x 14 x 9 inches (56 x 36 x 23 cm). European and Asian carriers are tighter, and low-cost carriers enforce it with a sizer and a smile.

Here's what to check before you book, not at the boarding door:

• United, American, Delta, Alaska: 22 x 14 x 9 inches, no published weight limit for economy carry-on.
• Southwest: 24 x 16 x 10 inches — generous, plus two free checked bags.
• British Airways, Lufthansa, Swiss: roughly 55 x 40 x 23 cm, and an 8 kg (17.6 lb) weight cap that is sometimes weighed at the gate.
• Singapore Airlines, Cathay Pacific, ANA: 7 kg (15.4 lb) weight limit in economy. They do weigh.
• Ryanair: a free small bag at 40 x 20 x 25 cm (fits under the seat). Priority & 2 Cabin Bags adds a 10 kg bag at 55 x 40 x 20 cm for around €6–€36 depending on route and timing.
• easyJet: free small bag at 45 x 36 x 20 cm; larger cabin bag is paid.
• Wizz Air: free bag at 40 x 30 x 20 cm; WIZZ Priority for the larger bag.

The trap: a bag that passes on Delta JFK→LHR may not pass on the easyJet hop from LGW to Porto three days later. If your itinerary includes any low-cost carrier in Europe or Asia, pack to the tightest limit on the trip, not the loosest.

Caveat: weight rules on legacy carriers are inconsistently enforced. I've never been weighed on United or BA in economy, but I've watched Lufthansa gate agents in Frankfurt pull out a scale during a Munich-bound boarding line in October. Don't count on leniency.

Pick a bag that fits the sizer — and your back

The bag matters more than anything inside it. A squishy 45L backpack can be stuffed over the limit; a structured roller physically cannot. That's a feature.

My current rotation:

• Peak Design Travel Backpack 45L ($299.95): expands and compresses between roughly 30L and 45L. Compressed, it fits the 55 x 40 x 20 cm European cabin size. Heavy empty (about 4.5 lb), but the hip belt saves your back on long walking days.
• Away The Carry-On ($275): 21.7 x 13.7 x 9 inches, polycarbonate shell. Fits US domestic sizers easily; snug but fine on most European legacies.
• Osprey Farpoint 40 / Fairview 40 (around $185): the classic. 40L, fits most international cabin sizes, laptop sleeve, stowaway straps.

What I'd skip: anything over 45L soft-sided if you're flying low-cost in Europe. A Tortuga Travel Backpack 40L works; a 55L hiking pack does not.

The clothing math: 1 week of clothes, any length of trip

The move isn't packing more — it's doing laundry once. I pack the same base for a 5-day trip or a 3-week trip, and run a wash around day 6 or 7. Most hotels over $150/night have next-day laundry (expensive), almost every Airbnb has a washer, and self-service laundromats run about €5–€12 a load in Europe, ¥400–¥800 at Japanese coin laundries.

For a mixed-weather, mixed-activity trip, here's the kit that goes in every time:

• 5 t-shirts or short-sleeve tops (merino wool if I'm re-wearing — Icebreaker and Smartwool tees run $75–$110 but don't stink after three wears)
• 2 long-sleeve layers (one button-down, one merino crew)
• 1 lightweight sweater or fleece
• 1 packable rain shell (Patagonia Houdini or similar, under 4 oz)
• 2 pairs of pants (one you wear on the plane, one in the bag)
• 1 pair of shorts or a swimsuit depending on destination
• 5 pairs of underwear, 4 pairs of socks (merino again)
• 1 pair of sneakers worn, 1 pair of sandals or lightweight shoes packed

That's it. The single most useful swap I made was going 80% merino — two Icebreaker tees replaced five cotton ones because I could wear each 2–3 times between washes.

Packing cubes: worth it, with one rule

Packing cubes don't create space; compression ones do. The Peak Design Packing Cubes (small $29.95, medium $39.95) have a compression zipper that actually shrinks volume by maybe 20–30%. Eagle Creek Pack-It Isolate Compression Cubes do the same for slightly less.

Rule: one cube for tops, one for bottoms, one for underwear/socks. Do not buy the 6-piece set and fill all six. That's just a different way to overpack.

Liquids: the 3-1-1 rule and the new CT scanners

In the US, TSA's 3-1-1 rule caps liquids at 3.4 oz (100 ml) per container, all inside one quart-size clear zip bag. The EU, UK, Japan, Australia, and Canada all use the same 100 ml limit.

The update worth knowing: airports with new CT scanners (LHR Terminal 5, JFK Terminal 4's newer lanes, most of Amsterdam Schiphol, Shannon, Rome Fiumicino) can theoretically allow larger liquids and bags-in, but enforcement is uneven and rules were partially rolled back in the UK in mid-2024. Pack to 100 ml. Don't gamble on a connecting airport.

My toiletry kit fits in a Muji clear pouch (about $8) and contains:

• Toothpaste travel tube, deodorant stick (solid = not a liquid)
• Shampoo bar or 3 oz bottle (a Lush shampoo bar runs about $14 and lasts 60+ washes)
• Sunscreen in a 3 oz squeeze bottle — buying on arrival in Asia is better; Japanese sunscreens like Biore UV Aqua Rich run about ¥800 at any Don Quijote
• Razor, floss, a small comb
• A few days of meds in the original bottle plus a photo of the prescription

Everything else I buy on arrival. A bottle of contact solution at a Boots in London is £4.50; hauling one from home isn't worth the cube space.

Electronics: the one-bag-inside-your-bag

Tech is where carry-on packs quietly blow past the weight limit. A 16-inch MacBook Pro alone is 4.7 lb — that's more than half of a Singapore Airlines 7 kg allowance.

What earns its place:

• Laptop (if working) or iPad Mini (if not)
• Phone + charger
• One multi-port GaN charger (Anker 735 Nano II 65W, around $55) replaces three bricks
• One universal adapter (Epicka, about $23) covers US/EU/UK/AU
• Over-ear or in-ear noise-canceling headphones (Sony WF-1000XM5 buds save space vs. over-ear)
• A 10,000 mAh power bank (Anker 523, around $30) — note: airlines cap power banks at 100 Wh carry-on only, never checked
• Kindle if it's a long trip — the Paperwhite at 7.2 oz replaces any books

Skip: a dedicated camera unless you actually use it. Modern iPhone and Pixel cameras have replaced my Sony RX100 on every trip since 2022.

The "don't forget" checklist I actually use

I keep a note on my phone called PACK. It has six lines, and I look at it the night before every trip:

1. Passport + second ID (driver's license or a photo of the passport on your phone, stored offline)
2. Cards + cash — one Visa, one Mastercard, about $100–$200 in local currency from a bank ATM on arrival, not an airport exchange booth
3. Meds + glasses/contacts
4. Chargers + adapter + power bank
5. Reservations offline — screenshots of hotel confirmations, train tickets, and the first night's address saved to Google Maps as offline
6. Empty water bottle — fill after security; saves $4–$6 a day

That's the whole list. Everything else is replaceable at a Target, a Boots, a Don Quijote, or a DM Drogerie for under $30.

What to wear on the plane (it's really packing)

The heaviest and bulkiest items go on your body. I fly in:

• Sneakers (not sandals — airports are cold and long)
• Jeans or hiking pants
• A merino t-shirt + the sweater or fleece
• The rain shell if it's bulky

This alone can save 3–4 lb off the bag weight and the difference between passing a 7 kg weigh-in and arguing at the gate.

Tradeoffs I've made peace with

Carry-on only isn't free. A few honest costs:

• You will do laundry mid-trip. Plan a slow afternoon around it — a Tokyo coin laundry at 10 p.m. is genuinely pleasant; a Paris Sunday when everything's closed is not.
• You'll re-wear outfits in photos. If that bothers you, check a bag.
• Winter trips are harder. A proper down jacket and boots eat half your volume. For sub-freezing destinations (Iceland in February, Hokkaido in January), I wear the heaviest layer and still sometimes check a bag.
• Souvenir space is limited. Either ship a box home (Japan Post EMS to the US is about ¥7,000–¥12,000 for a medium box, 3–5 days) or pack a foldable Baggu tote and pay for a checked bag on the return.

Your next step

Before your next trip: pull out the bag you plan to use, lay everything you think you're bringing on the bed, and remove one-third of it. Then weigh the bag on a bathroom scale holding it, subtracting your own weight. If it's over 8 kg (17.6 lb) and you're flying any European or Asian carrier, keep cutting. The bag you actually carry through three airports and a cobblestone street in Lisbon is the one you packed the second time, after you questioned every item.