Kids’ Under-Seat Bag Packing List for Flights (with Printable Checklist)

Last reviewed: October 2026. Airline and security rules change, so check your airline and departure airport before you fly.

The under-seat bag is the one piece of luggage you can always reach. Overhead lockers fill up, cabin bags get taken at the gate, and checked luggage sometimes arrives a day late. Whatever is in the bag at your feet is what you have for the whole flight, and possibly for the first night. This guide covers what to put in a child’s under-seat bag (or the family’s shared one), how it changes with age, and which security and battery rules affect what you can carry.

Quick answer

• Pack for delays, not for the scheduled flight. Food, nappies and a change of clothes for at least double the flight time.
• Baby milk and baby food are exempt from the 100 ml liquid limit in both the US and the UK, in quantities for the journey. Tell the security officer at the start of screening.
• Power banks must travel in the cabin, never in checked luggage. If your bag is checked at the gate, take them out first.
• Check the size limit. Under-seat allowances vary by airline. easyJet, for example, allows 45 x 36 x 20 cm (as of October 2026).
• Let older children carry their own. A small backpack with their own snacks, headphones and activities gives them something to manage.

Why the under-seat bag matters most

On a full flight you may not be able to stand up and open the overhead locker for long stretches: during take-off and landing, when the seatbelt sign is on, or when the trolley is in the aisle. With a small child, those are often the moments you need something right now. A dropped dummy, a leaking nappy, a spilt drink, a child who suddenly needs a jumper. If it is at your feet, it is solved in seconds.

The American Academy of Pediatrics’ guide to flying with a baby (HealthyChildren.org, updated March 2026) recommends several changes of clothing, dressed in layers, plastic bags for soiled items, nappy-changing supplies and disposable changing pads, and toys and books, with a tablet as a backup. Those are the core of the bag. Everything else is about age, flight length and how your child copes.

How big can the bag be?

Every airline sets its own size for the bag that goes under the seat, and many low-cost airlines check it at the gate. Two examples from airline websites as of October 2026:

Sources: easyJet “Cabin bags and hold luggage” and Delta “Carry-On Baggage” pages, checked 24 October 2026.

If your airline isn’t listed, look up its cabin baggage page before you buy a bag. Some airlines publish exact dimensions, some only say the bag must fit under the seat. A child with their own seat normally gets their own allowance, so a family of four may be able to bring four under-seat bags. A lap infant usually does not, although some airlines allow an extra changing bag.

Liquids, milk and baby food: what security allows

In the US (TSA)

The Transportation Security Administration allows formula, breast milk, toddler drinks and baby or toddler food, including puree pouches, in carry-on bags in amounts over 3.4 oz (100 ml). They don’t need to fit in the quart-sized liquids bag, but you should tell the officer at the start of screening and take them out for separate screening. Ice packs, freezer packs, gel packs and liquid-filled teethers are also allowed. Children 12 and under can keep their shoes, light jackets and hats on during screening.

In the UK

At most UK airports, liquids in hand luggage must be in containers of no more than 100 ml, in a single transparent resealable bag of up to one litre (about 20 x 20 cm), one bag per person. GOV.UK says you can take enough baby food, baby milk and sterilised water for the journey when travelling with a baby, and that these are allowed in hand luggage only if the baby is travelling with you. Containers up to 2 litres are allowed at all UK airports for baby food or baby milk. Breast milk is allowed in hand luggage even without the baby, in containers of up to 2,000 ml, but frozen breast milk is not. Each container is screened and staff may need to open it.

Some UK airports now allow larger containers for all liquids, but the rules are not the same everywhere. GOV.UK advises checking the rules at your departure airport and any connecting airport, including on the way home.

What this means for the bag

• Keep milk, baby food and pouches together in one easy-to-lift pouch, so you can hand it over at security in one go.
• Pack the child’s other liquids (sun cream, nappy cream, hand gel) in the family’s clear liquids bag, in containers of 100 ml or less, unless you know your airports allow more.
• An empty water bottle per child is easy. Fill it after security.

Power banks and devices

The US Federal Aviation Administration says spare lithium batteries, including power banks and battery charging cases, must be carried in carry-on baggage only. If a bag is checked at the gate or planeside, the power banks must be taken out and kept with you in the cabin. Terminals must be protected against short circuits, and airlines may set stricter limits on how many power banks you can carry. GOV.UK also says your devices should be charged before you travel: if a device doesn’t switch on when security asks, you won’t be allowed to take it onto the aircraft.

So the power bank belongs in the under-seat bag, not the cabin case that might get taken at the gate. Charge the tablet the night before, download films and games at home (in-flight Wi-Fi is unreliable), and pack a cable for each device.

What to pack, by age

Babies (0 to 12 months)

• Feeds for the whole journey plus delays: formula portions or ready-to-feed cartons, bottles, or breastfeeding cover if you use one.
• Dummy and spare. The AAP suggests breastfeeding, bottle-feeding or a dummy during take-off and landing to help with ear pressure.
• Nappies: one per hour of travel is a common rule of thumb, plus extras for delays.
• Wipes, nappy cream, disposable changing mats and nappy bags.
• Two full changes of clothes for the baby, and a spare top for you.
• Muslins or burp cloths, a light blanket and a sleepsuit for long flights.
• A small toy or two that make no noise.

Toddlers (1 to 3 years)

• Lots of small snacks in separate containers. Snacks fill time as well as stomachs.
• A leak-proof cup or bottle, empty through security.
• Nappies or pull-ups, wipes and a full change of clothes, or two if potty training.
• New small activities wrapped up, handed out one at a time: sticker books, a magnetic drawing board, small board books.
• A comfort item for sleep.
• Child-sized headphones and a downloaded show or two for the hardest stretch.

Preschool and school-age children (4 to 12 years)

• Their own backpack, packed with them, carried by them.
• Headphones, a charged tablet or e-reader with downloaded content.
• Activity books, a pencil case, a pack of cards or a travel game with few loose pieces.
• Snacks and an empty water bottle.
• A hoodie or light jumper: cabins can feel cold.
• Socks for long flights, and a small pillow if they sleep better with one.

The family “grab pouch”

Whatever the ages, one small zipped pouch at the top of the bag makes life easier. It holds the things you need in a hurry, so you don’t empty the whole bag on your lap:

• Wipes and hand sanitiser
• Tissues
• A dummy or a favourite small toy
• Sick bags or nappy bags
• Any medicine your child might need during the flight, in its original packaging
• Passports and boarding passes, if you don’t keep them on you

The AAP advises not giving antihistamines such as diphenhydramine to make a child sleep without asking a doctor first, as some children become more alert rather than sleepy. If your child takes regular medicine, keep enough for a few extra days in the under-seat bag, not in checked luggage.

Printable checklist

Use your browser’s print button to print this list.

Every child

• ☐ Passport or ID, boarding pass (on a phone or printed)
• ☐ Change of clothes (two for babies and toddlers)
• ☐ Light jumper or hoodie
• ☐ Snacks for double the flight time
• ☐ Empty water bottle or leak-proof cup
• ☐ Wipes and tissues
• ☐ Comfort item
• ☐ Medicine in original packaging
• ☐ Plastic bags for wet or dirty clothes

Babies and toddlers

• ☐ Milk or formula for the journey, plus extra for delays
• ☐ Bottles, and a dummy and spare
• ☐ Baby food or pouches
• ☐ Nappies, nappy cream, changing mats, nappy bags
• ☐ Muslins and a light blanket
• ☐ Quiet toys and board books

Older children

• ☐ Headphones
• ☐ Charged tablet with downloaded content
• ☐ Activity book, pens or pencils
• ☐ Cards or a small travel game
• ☐ Socks and a small pillow for long flights

For the adults

• ☐ Power bank (cabin only) and cables
• ☐ Clear liquids bag with 100 ml containers
• ☐ A spare top for you
• ☐ Pen for landing cards

Choosing the bag itself

The right bag is the one that fits your airline’s limit and your child’s back. A few things to look for, rather than a particular brand:

• Size: measure against your airline’s under-seat dimensions, including wheels and handles.
• Opening: a bag that opens wide (clamshell style) is easier to search on your lap than a deep top-loader.
• Pockets: an outside pocket for the water bottle and one for tissues and wipes.
• Weight: for a child carrying their own bag, keep it light enough that they can carry it through the airport without help.

If you’re shopping, these Amazon searches show the main categories: kids’ travel backpacks, volume-limiting kids’ headphones, leak-proof kids’ water bottles and clear liquids bags. We haven’t tested these products. Check the measurements against your airline before you buy.

As an Amazon Associate we earn from qualifying purchases. Read our affiliate disclosure.

Next steps

For the rest of the luggage, see our family packing list that fits in one bag. For the flight itself, read flying long-haul with kids. And for the day out once you’ve landed, the city break with a toddler packing list and our must-have gear page pick up where this list stops.

Frequently asked questions

Does a child get their own under-seat bag?

Usually, if they have their own seat. easyJet, for example, gives children over 2 and infants with their own seat the same cabin allowance as adults. Lap infants usually don’t get their own bag, but some airlines allow an extra changing bag. Check your airline’s page.

Can I take baby milk through security?

Yes. TSA allows formula, breast milk and toddler drinks over 3.4 oz in carry-ons, and GOV.UK allows enough baby milk, baby food and sterilised water for the journey when the baby travels with you. Tell security at the start of screening.

Can my child take a juice box through security?

TSA lists toddler drinks with formula and breast milk. In the UK, the baby-food exception covers baby food and baby milk; other drinks follow the 100 ml rule at most airports. The simplest option is to buy drinks after security.

Can a power bank go in checked luggage?

No. The FAA says spare lithium batteries and power banks must be carried in the cabin. If your bag is checked at the gate, take the power bank out first.

How many nappies should I pack for a flight?

There is no official number. Many parents pack one per hour of travel time, door to door, plus several extra for delays.

Should I give my child medicine to help them sleep on the plane?

The American Academy of Pediatrics advises against giving diphenhydramine (Benadryl) without asking your doctor first, because some children become more alert, not sleepy.

What helps with ear pain on take-off and landing?

For babies, the AAP suggests breastfeeding, a bottle or a dummy during take-off and landing. For older children, a drink or a snack to chew can help. If your child has had an ear infection or ear surgery in the two weeks before the flight, ask your doctor whether it’s safe to fly.