Every overpacked suitcase tells the same story.

Three pairs of shoes “for options.” A second jacket in case the first one is wrong. The full-size conditioner, because the hotel one might be terrible. A novel, a backup novel and an e-reader containing several hundred novels.

And then, at the other end, you wear the same two outfits on rotation and carry the rest around like a penance.

Travelling carry-on only is genuinely lovely. No waiting at the carousel. No lost-bag anxiety. No hauling a giant case up the stairs of a walk-up. But it only works if you’re ruthless about what goes in.

So here’s the test.

The Carry-On Test: three questions per item

Before anything goes in the bag, it has to pass all three:

• Will I definitely use it on this trip? Not “might.” Definitely. “Just in case” is how a weekend bag ends up weighing as much as a toddler.
• Can it get through security? Liquids, gels, sprays and batteries all have rules. More on those in a minute.
• Does it earn its space? Does it work with more than one outfit, serve more than one purpose, or make the trip meaningfully better? A pair of shoes that only goes with one dress has not earned its space.

Fail any one, and it stays home. You can almost always buy toothpaste where you’re going.

Fail any one, and it stays home. You can almost always buy toothpaste where you’re going.

First, check your airline’s actual limits

Before you pack anything, look up your airline’s carry-on rules for your specific fare. Size and weight limits, and whether you get a full-size carry-on or only a smaller personal item, vary by airline and sometimes by fare type. Some basic fares don’t include a full carry-on at all.

This takes two minutes and saves you from discovering at the gate that your “carry-on” is now a checked bag with a fee attached.

The liquids rules, in Canada and the U.S.

The good news: the core rule is essentially the same on both sides of the border.

Canada (CATSA)

The Canadian Air Transport Security Authority says containers of liquids, non-solid food and personal items in your carry-on must be 100 ml/100 g (3.4 oz) or less. All of them must fit in one clear, resealable plastic bag no more than 1 L in capacity — roughly 15 cm by 23 cm (6 in. by 9 in.) or 20 cm by 17.5 cm (8 in. by 7 in.), according to CATSA. Each passenger gets one bag.

United States (TSA)

The Transportation Security Administration’s “3-1-1” rule: liquids, gels and aerosols in travel-size containers of 3.4 ounces (100 millilitres) or less, all in one quart-size bag, with one bag per passenger. TSA’s rule explicitly covers creams and pastes too.

What actually counts as a liquid?

More than you’d think. A useful rule of thumb based on how both agencies describe it: if it can be poured, pumped, squeezed, sprayed or spread, assume it counts. That includes things like:

• Shampoo, conditioner, body wash, lotion, sunscreen
• Foundation, tinted moisturizer, liquid concealer, mascara, lip gloss
• Toothpaste, mouthwash, hand sanitizer
• Hair products: gel, mousse, dry-shampoo spray, hairspray
• Perfume
• Food like yogurt, hummus, nut butters and dips

One important detail: the limit is about the size of the container, not how much is left in it. A 200 ml bottle with a splash at the bottom is still a 200 ml bottle.

What’s exempt

Both agencies make room for things you genuinely need:

• Medications. CATSA says prescription medicines are allowed, along with essential non-prescription medicines such as cough syrup, decongestant spray, saline solution and eye-care products — they don’t need to go in your 1 L bag, but you need to declare them for inspection. TSA allows “larger amounts of medically necessary liquids, gels, and aerosols in reasonable quantities for your trip,” which you should tell the officer about at the checkpoint.
• Baby food, formula and breast milk. CATSA allows baby food, milk, liquid formula, water and juice over 100 ml when you’re travelling with an infant under two, and breast milk over 100 ml whether or not your child is with you. TSA allows formula, breast milk, toddler drinks and baby food (including purée pouches) over 3.4 oz in reasonable quantities; tell the officer at the start of screening and take them out of your bag to be screened separately. Your child doesn’t need to be travelling with you to bring breast milk.
• Duty-free. There are specific conditions for duty-free liquids, especially on connecting flights (TSA, for example, requires a sealed, tamper-evident bag and a recent receipt). If you’re buying a bottle of something at the airport, read the rules first.

A note on rule changes

Security rules can and do change. In September 2026, CBS News reported, citing unnamed senior administration officials, that TSA was considering letting PreCheck travellers bring water bottles through checkpoints at a small number of airports with newer CT scanners. No airports or start date were named, and as of this writing TSA has not announced the change on its own website. Until an agency announces a change on its own website, assume the 100 ml / 3.4 oz rule applies — and check catsa-acsta.gc.ca or tsa.gov before every trip.

Batteries: carry-on, not checked

This one is easy to miss, and it matters more than the liquids rule.

The U.S. Federal Aviation Administration says spare lithium batteries — including power banks — must travel in carry-on baggage only, never in checked bags. If your carry-on gets gate-checked or taken planeside, you need to take the spare batteries out and keep them with you in the cabin. The FAA limits spare lithium-ion batteries to 100 watt-hours each (larger ones, up to 160 Wh, need airline approval), and notes that many airlines set stricter limits, including on how many power banks you can bring.

Transport Canada likewise advises keeping lithium batteries in your carry-on, never in checked luggage.

So: power bank goes in the bag that stays with you. Always. And check your airline’s own rules before you fly, since carriers can be stricter.

The actual list

Here’s a flexible carry-on packing list for a trip of about three to five days. Adjust for weather, activity and your own life.

Clothes: the formula

• Bottoms: two — one you’ll wear on the plane, one in the bag. Ideally both work with every top.
• Tops: three or four, in colours that go with both bottoms.
• One “nicer” piece: a dress, a silk-ish top, or a blazer that turns any outfit into dinner.
• One layer: a cardigan, light sweater or jacket. Wear the bulkiest one on the plane.
• Underwear and socks: one per day, or plan a quick sink wash.
• Sleepwear: one set, or a t-shirt that’s doing double duty.

Pick one colour family and stick to it. When everything goes with everything, three tops and two bottoms become six outfits.

Shoes: two pairs, maximum

Wear the bulkiest pair (sneakers, boots) on the plane. Pack one other pair that can handle both walking and dinner. Shoes are the heaviest, bulkiest, least flexible thing you’ll pack. They fail the Carry-On Test more often than anything else.

Toiletries: your 1 L / quart bag

• Decant your favourites into small, refillable travel containers that are clearly 100 ml / 3.4 oz or less.
• Check whether your accommodation supplies shampoo, conditioner and body wash. If it does, that’s space back in your bag.
• Prioritize the products you’re genuinely particular about — the face moisturizer, the sunscreen — and skip the ones you’re not.
• Pack the bag last and put it somewhere easy to reach, since you may need to take it out at security.

Your personal item: the “if everything else disappeared” bag

This is the smaller bag that stays at your feet. Pack it as if your main carry-on might get gate-checked:

• Passport or ID, boarding pass, wallet
• Any medications you need, in their original labelled containers where possible
• Phone, charger, power bank (see above)
• Glasses or contacts
• A layer — planes are rarely the temperature you’d choose
• An empty reusable water bottle to fill after security
• Snacks (solid foods are generally fine; spreads and dips count as liquids)

What usually fails the test

Things that tend to get packed and not used:

• The “just in case” outfit for an event that isn’t on the itinerary
• A third pair of shoes
• Full-size liquid toiletries (they can’t go through security in a carry-on anyway)
• A hair dryer, if your accommodation provides one — check first
• More books than you can read in the time you’ll actually have

The fix isn’t willpower. It’s doing the test honestly at home, where it’s free, instead of at the airport, where it isn’t.

The fix isn’t willpower. It’s doing the test honestly at home, where it’s free, instead of at the airport, where it isn’t.

Pack it in the right order

• Shoes at the bottom, near the wheels, if it’s a roller.
• Rolled or folded clothes in the middle. Packing cubes help if you like compartments.
• Liquids bag and anything you’ll need at security on top or in an outside pocket.
• Electronics and spare batteries together, easy to reach, in the bag that stays with you.

If you’re packing for a short, restful trip — the two-night kind — you need even less than you think. We go through how to plan one in The Two-Night Escape: How to Plan a Weekend Away That Actually Feels Restful.

MUDDY FINDS: Passes the Carry-On Test

• Amazon Essentials 4-Piece Packing Cubes Set — If you like compartments, cubes keep rolled clothes in the middle of the bag where the packing order says they belong. Shop on Amazon
• Osprey Ultralight Clear Liquids Pouch — A clear, zippered pouch keeps your liquids together and easy to pull out at security (check it against your 1 L / quart limit). Shop on Amazon
• Travelpro Maxlite 5 Softside Carry-On Spinner — A lightweight carry-on leaves more of your airline’s weight allowance for what you’ll actually use (check your fare’s size limits first). Shop on Amazon

Muddy Finds may include affiliate links. As an Amazon Associate, Muddy Stilettos earns from qualifying purchases, at no extra cost to you.

The Good-Life One’s take

The fantasy of travel is a suitcase full of options. The reality is that the best trips are lighter than that.

Less to carry means less to manage. Less to manage means more attention left over for the actual trip: the walk from the station, the first coffee somewhere new, the view you came for.

Run the test. Check the rules. Wear the boots on the plane.

And leave the backup novel at home. You weren’t going to read it.

Leave the backup novel at home. You weren’t going to read it.

More trip-planning ideas live on our Home, Food & Travel desk.

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The Muddy Home, Food & Travel Desk covers the food, homes, trips and small luxuries that make real life better — from Tuesday-night dinners to the weekend away you’ve been promising yourself.

Featuring The Good-Life One: finds the places, recipes, hotels and little luxuries actually worth knowing about — and understands Tuesday night, budgets and carry-on limits.

Security and battery rules summarized here were current at the time of writing and can change. Always confirm with CATSA, TSA, Transport Canada, the FAA and your airline before you travel.

Sources

• Liquids, Non-solid Food & Personal Items — Canadian Air Transport Security Authority (CATSA)
• What is the 3-1-1 liquids rule? — Transportation Security Administration (TSA)
• Traveling with Children — Transportation Security Administration (TSA)
• Liquids Rule — Transportation Security Administration (TSA)
• Liquid Medications — Transportation Security Administration (TSA)
• PackSafe: Lithium Batteries — Federal Aviation Administration (FAA)
• Lithium batteries part 2: What you didn’t know about travelling with them — Transport Canada
• Some TSA PreCheck travelers may be able to bring full water bottles through airport security soon, officials say — CBS News