A backpack is the most useful bag a child can have on a trip, but one that is too big or too heavy ends up on a parent's shoulder. This guide covers sizes by age, how to fit a pack, the AAP's 15% weight guideline and what to pack for flights and days out.
Last reviewed: October 2026. Fit advice comes from the American Academy of Pediatrics (AAP). We haven’t tested individual backpacks.
A backpack is the most useful piece of luggage a child can have. It leaves their hands free, fits under a plane seat, works on trains, ferries and cobbled streets, and goes from the flight to the beach to the museum. But a backpack that is too big, too heavy or badly adjusted soon ends up on a parent’s shoulder. This guide explains how to choose a travel backpack by age and body size, how to fit it, how much a child should carry, and what to put in it.
Kids’ Travel Backpacks by Age: Size, Fit and How Much They Can Carry
Quick answer
How much can a child carry?
The AAP’s guideline is that a backpack shouldn’t weigh more than 15% of the child’s body weight. It also says that if a child has to lean forward to carry the pack, it is too heavy. On a trip, this works out like this:
| Child’s weight | Maximum pack weight (15%) |
|---|---|
| 15 kg (33 lb) | 2.25 kg (5 lb) |
| 20 kg (44 lb) | 3 kg (6.6 lb) |
| 25 kg (55 lb) | 3.75 kg (8.3 lb) |
| 30 kg (66 lb) | 4.5 kg (9.9 lb) |
| 40 kg (88 lb) | 6 kg (13.2 lb) |
Calculated from the AAP’s 15% guideline (HealthyChildren.org, updated August 2026). Weigh the packed bag on a bathroom or luggage scale.
That isn’t much. A tablet, a water bottle, a jumper and a book can already reach the limit for a small child. That’s why a child’s travel backpack should hold their own flight and day-out things, not their clothes for the trip.
Decision table: backpack size by age
| Age (approx.) | Typical size | What goes in it | Look for |
|---|---|---|---|
| 2 to 3 | Very small, toddler size | Comfort toy, snack, board book | Chest strap; light; a design they love. Expect to carry it yourself. |
| 4 to 6 | Small, pre-school size | Snacks, water bottle, activity book, jumper | Chest strap; easy zips; side bottle pocket |
| 7 to 9 | Small to medium daypack | Headphones, tablet, book, snacks, water, jumper | Padded back and straps; fits under the plane seat |
| 10 to 12 | Medium daypack | As above, plus their own toiletries and a change of clothes | Adjustable back length or a size range; waist strap |
Ages are a rough guide. Children of the same age vary a lot in size, so check the fit on your child.
How to fit a backpack
The AAP’s fit advice for children’s backpacks:
- Two broad, padded, adjustable straps, kept the same length. Don’t let children sling the bag over one shoulder.
- Use the waist belt or chest strap to spread the weight.
- A padded back is more comfortable and protects against sharp items inside.
- Position: the bottom of the pack should rest in the curve of the lower back, from about waist level to 1 to 2 inches below the shoulders, and never more than 4 inches below the waistline.
- Packing: put the heaviest things closest to the back and spread the rest evenly left and right.
Before you buy, let your child try the backpack on with a few things inside. Walk around the shop or the house. If the straps slip off their shoulders or the bag hangs low on their bottom, it’s too big.
What to look for in a travel backpack
What to pack in it
For the flight
- Headphones and a charged tablet with downloaded content
- A book or activity book and pencils
- Snacks and an empty water bottle (fill after security)
- A light jumper or hoodie
- A small comfort toy
Our under-seat bag packing list covers this in more detail, including what security allows.
For days out
- Water bottle and a snack
- Sun hat or rain jacket, depending on the weather
- A small notebook for collecting stamps or drawing
- Their museum or park map
Keep in an adult’s bag instead
- Passports, tickets and money
- Medicines
- Power banks (they must stay in the cabin on flights; keep them with you)
Common mistakes
Shopping by category
These Amazon searches cover the main sizes: toddler backpacks with a chest strap, kids’ travel backpacks and kids’ daypacks, plus luggage scales for checking the weight. We haven’t tested these products and don’t rank them.
As an Amazon Associate we earn from qualifying purchases. Read our affiliate disclosure.
Next steps
For the rest of the family’s luggage, see kids’ luggage: carry-on, ride-on or backpack and the family packing list that fits in one bag.
Gear for this list
Shop the items families most often ask about. These are Amazon search links, not product rankings – compare sizes and airline rules before you buy.
- Packing cubes
- Power bank
- Baby carrier
- Travel cot
- Stroller rain cover
- Portable blackout blind
- Travel plug adapter
- Portable changing mat
Affiliate links: as an Amazon Associate we earn from qualifying purchases, at no extra cost to you.
Final thoughts
Choose by back length rather than age, keep the packed weight under 15% of your child's body weight, use both straps and the chest strap, and keep passports, medicine and power banks in an adult's bag.
Frequently asked questions
How heavy should a child's backpack be?
The American Academy of Pediatrics says no more than 15% of the child's body weight. If they have to lean forward to carry it, it's too heavy.
What size backpack does a 5-year-old need?
A small pre-school backpack with a chest strap is usually right. Check the fit: it should sit in the curve of the lower back and not hang more than about 10 cm below the waist.
Can a child's backpack be their personal item on a plane?
Yes, if the child has their own seat and the backpack fits the airline's under-seat size.
Should a child carry their own passport?
No. Keep passports, tickets, medicines and power banks in an adult's bag.
Is a rolling backpack better for travel?
It can help with a heavier load, and the AAP mentions rolling backpacks as an option when a pack is too heavy. They're less handy on stairs and cobbles.
