Carry-on essentials

What goes in your carry-on: a decision rule, not a list

Every carry-on decision starts with one question: If my checked bag disappears, can I still do everything I need to do for the next 48 hours? The answer determines what must stay in your hands. This method separates the required from the merely useful, using only official sources and your destination’s specific rules.

Carry-on is not “everything I might want.” It is two things: what you cannot do without and what you cannot replace at your destination. Everything else goes in checked luggage or stays home.

What you cannot do without covers safety, medication, and documents. What you cannot replace covers valuables, critical electronics, and items that are not available where you are going (a specific prescription lens, a rare medical device, a work laptop with proprietary software).

The required list

These items are non-negotiable for any trip. Each must be verified against your specific destination and carrier before you pack.

1. Government-issued photo ID (adults 18+)
TSA requires a valid government-issued photo ID for domestic travel in the United States (TSA, 2025). For international travel, you need a passport that meets the destination’s validity rule. The common “six months beyond travel” rule is not universal: some countries require three months from entry, others six. Check the destination’s official immigration website, not a travel agent.

2. Medication, in original containers, with labels
Prescription medications must remain in the original pharmacy packaging with the label showing your name and the prescribing doctor (CBP, 2024). Carry enough for the entire trip plus a 7-day supply in case of delay (FEMA, 2024). Keep all medication in your hand luggage, never in checked luggage (WHO, 2023). If you use a controlled substance, check the destination country’s embassy for any additional declaration forms; some countries require prior approval.

3. Travel documents and copies
Your passport, visa (if required), boarding pass, and any health-entry proof (a yellow fever vaccine certificate if arriving from an endemic zone). Carry a photocopy of your passport data page and visa separately from the originals. For US citizens, register your trip with the State Department’s STEP program (free, smartraveller.gov is the UK equivalent) so the embassy knows where you are.

4. Emergency contact and medical information
A printed card with your name, blood type, allergies, existing conditions, and emergency contact numbers (first responder, then family, then embassy). Lock your phone’s lock screen with an ICE (In Case of Emergency) contact for first responders. Do not rely on a digital file; phones run out of battery.

5. Spare batteries and power bank
Lithium-ion batteries for cameras, phones, and laptops must travel in the cabin only. Each battery is limited to 100 watt-hours (Wh) (IATA, 2025). Power banks are treated as spare batteries. Check the airline’s specific limit; some cap the number of batteries you can carry.

6. Liquids, gels, and aerosols in a single quart-sized bag
Each container must be 3.4 oz (100 ml) or less (TSA, 2025). The bag must be clear and sealable. If you need larger amounts for medical reasons, you must declare them at the screening checkpoint and they will be subject to additional screening.

7. Electronics larger than a cell phone
Laptops, tablets, e-readers, and cameras larger than a phone must be removed from your bag and placed in a separate bin (TSA, 2025). Keep them accessible. A tablet in a deep compartment will cause a re-scan.

8. A change of clothes (minimum)
If your checked bag is delayed, you need enough to get through the first day: one shirt, one pair of underwear, one pair of socks, and a travel-sized toothbrush and toothpaste. Roll them into a small packing cube.

The useful list

These items are not required, but they solve the most common hand-luggage failures:

• Empty water bottle, fill it after security.
• Travel-sized hand sanitiser, 100 ml or less.
• Snacks, non-perishable, no liquids or gels.
• Phone charger and cable, the one you cannot buy at the airport at 11 p.m.
• Eye mask and earplugs, for sleep on the plane or in a noisy terminal.
• Pen, for customs forms and immigration cards.
• Printed itinerary, with hotel name, address, and reservation number. Do not rely on your phone.

The forbidden list

These items are banned or restricted and will be confiscated:

• Liquids over 3.4 oz (100 ml) in the cabin (TSA, 2025)
• Knives with blades over 6 cm (2.36 in), and even smaller ones may be prohibited by the airline (IATA, 2025; verify with your carrier)
• Spare lithium batteries over 100 Wh (IATA, 2025)- Self-defence sprays, pepper spray, or mace
• Tools (screwdrivers, wrenches, pliers) over7 inches; check the airline list

How to verify

Do not use a generic “what to pack” article or a third-party travel site. Use only the official source for your specific situation:

• Airline rules: check the airline’s website for cabin-bag dimensions, weight limit, and prohibited items. Sizes vary by airline and aircraft type.
• Entry rules for your destination: use the country’s official immigration website. For US citizens, travel.state.gov. For UK citizens, gov.uk/foreign-travel-advice. For Canada, travel.gc.ca. For Australia, smartraveller.gov.au.
• Health requirements: WHO International Travel and Health (who.int/travel-advice) for global advice; CDC Yellow Book for US-specific recommendations (cdc.gov/yellowbook).
• Customs rules: for medication, food, and valuables, check the destination’s customs website. Some countries require you to declare prescription medication on arrival.

The deadline

Check your documents 2 weeks before departure so you have time to renew a passport or get a visa. Check again 48 hours before for any last-minute rule changes (a new travel advisory, a cancelled flight, a changed visa requirement). Government travel advisories are updated weekly, but the update lag is 2-5 business days for routine changes. Do not wait until the day before.

The emergency kit

A small emergency kit in your hand luggage covers the first 48 hours of a delay or lost luggage. It is not a full 72-hour kit (that goes in checked luggage or at your destination). Contents:

• 7-day supply of essential medication (in original containers)
• First-aid basics (band-aids, antiseptic wipes, pain reliever, anti-diarrhoeal)
• Whistle (for attracting attention in an emergency)
• Dust mask (for smoke or dust in a terminal)
• Moist towelettes (for cleaning hands or surfaces)
• Small flashlight with spare batteries
• Phone power bank (fully charged)
• Printed emergency contact list with embassy numbers

The checklist method

Do not use a pre-printed list that someone else wrote. Build your own by writing down every item you know you cannot replace at your destination. Then cross-check each item against the airline’s prohibited list and the destination’s customs rules. The checklist is reliable only after you have used it and revised it; a list that has never been tested in a real trip is unreliable (The Checklist Manifesto, Gawande).

The one failure mode

The most common mistake is over-packing because you follow a generic “travel essentials” list instead of your own decision rule. If you are carrying something “just in case,” ask: Can I buy this at my destination in under an hour? If yes, leave it at home. If no, and it is a safety, medical, or document item, keep it. If no, and it is a nice-to-have, leave it at home.