The right size backpack for kindergarten is set by your child’s back, not by a fixed number of inches. The American Academy of Pediatrics (AAP) says the bag should be proportional to your child’s height and go from waist level up to about 1 to 2 inches below the shoulders, and Consumer Reports adds that it should be no wider than your child’s body. Guidance checked on 19 October 2026.
None of the health bodies we read gives a size in inches or liters for a kindergartener, so measure your child, then compare with the bag’s stated size. A backpack maker’s chart that does give a figure is quoted below, and our own preschool backpacks are listed as examples.
| Fit point | What the guidance says | Who says it |
|---|---|---|
| Height | From waist level up to about 1 to 2 inches (2.5 to 5 cm) below the shoulders | AAP |
| Height | From about 2 inches (5 cm) below the shoulder blades to the waist | Consumer Reports |
| Lowest point | Never more than 4 inches (10 cm) below the waistline | AAP, American Chiropractic Association (ACA) |
| Width | No wider than your child’s body | Consumer Reports |
| Packed weight | No more than 15% of your child’s body weight | AAP |
| Packed weight | No more than 10% of your child’s body weight | ACA, American Occupational Therapy Association (AOTA) |
| Straps | Two broad, padded shoulder straps | AAP, ACA, Consumer Reports |
Kindergarten backpack size: how to measure your child
A kindergarten backpack fits when it covers your child’s back from just below the shoulders to the waist, and no more. Two measurements give you the largest bag that fits.
- Height: with your child standing, measure from about 1 to 2 inches below the top of the shoulders down to the waist, at the level of the belly button. That is the tallest the bag should be.
- Width: measure across your child’s back. The bag should be no wider than that.
Then read the height and width on the product page. A bag that would hang more than 4 inches below the waistline is too big, according to both the AAP and the ACA.
The AAP also warns that “Bigger is not necessarily better.” The weight rule below matters as much as the size.
How heavy can a kindergarten backpack be?
Packed, a backpack should weigh no more than 15% of your child’s body weight according to the AAP, and no more than 10% according to the ACA and the AOTA. For example, if your child weighs 40 lb (18 kg), that is 6 lb (2.7 kg) at most by the AAP figure, and 4 lb (1.8 kg) by the ACA and AOTA figure.
The empty bag counts toward that total. The AOTA also advises loading the heaviest items closest to your child’s back and balancing the rest so your child can stand up straight.
What to look for besides size
Once the size is right, these are the features the AAP, the ACA and Consumer Reports point to.
- Straps: two wide, padded shoulder straps (AAP, ACA, Consumer Reports). The ACA adds that they should be adjustable, so the bag fits your child’s body, and asks children to wear both straps.
- Back: a padded back panel (AAP).
- Extra strap: a waist belt or chest strap (AAP). Consumer Reports calls a waist strap useful but “not essential”.
- Skip: drawstring bags, which Consumer Reports advises against.
- Rolling bags: the AAP suggests one if the school allows it, while the ACA says rolling bags should be used cautiously and only by children who cannot carry a backpack.
Full size or mini backpack for kindergarten?
Choose the largest bag that still fits your child’s back, and no larger. If your school’s supply list asks for a “full size” backpack, ask what the bag must hold, such as a folder, then check that the bag’s stated height takes it without going past your child’s measurements. If a full size bag would hang below the waist, the health guidance says it is too big for now, whatever the label.
Check that a folder fits
If your child will carry a folder, check it against the bag before you buy. Letter-size paper is 8.5 x 11 inches (21.6 x 27.9 cm), and a folder that holds it is larger still, so a bag whose stated outside height is about 30 cm (12 in) may not take one flat. Compare the inside of the bag with the folder itself, not the outside size on the label.
What size charts from backpack makers suggest
Backpack makers do give a number, and L.L.Bean is one example. Its guide to choosing a school backpack, read on 19 October 2026, sorts its packs by load, from “SMALL Up to 20L”, and separately by age, from “AGE 4-7 Preschool and early elementary school”. Its FAQ links the two, saying small packs “(up to 20 liters) are perfect for kids just starting out in kindergarten or elementary school.”
That is one maker’s chart for its own range, not health guidance, and other makers’ charts differ. Take up to 20 liters as a rough starting point, then check the bag against your child’s back with the two measurements above. Our preschool backpacks below state no capacity in liters, so compare them by their size.
Our preschool backpacks and their stated sizes
Our preschool backpacks collection holds small bags for the first years of school, sized for a snack, a soft toy and a change of clothes. The six below have their dimensions stated on the product page. These are the bags’ stated dimensions, and a soft bag packed full bulges, so measure it packed against your child’s back. None states a capacity in liters. Inches and pounds are our rounded conversions.
| Backpack | Stated size | Empty weight | Stated features |
|---|---|---|---|
| Our small dinosaur backpack in nylon | 22 x 18 x 9 cm (8.5 x 7 x 3.5 in) | 0.1 kg (0.2 lb) | Adjustable straps, zipper |
| Our preschool backpack with a dinosaur driving a car | 25 x 20 x 8 cm (10 x 8 x 3 in) | Not stated | 50 cm (19.5 in) shoulder straps, top handle, long safety strap for walks, machine-washable nylon |
| Our 3D panda backpack | 30 x 25 x 15 cm (12 x 10 x 6 in), 30 cm tall | 0.36 kg (0.8 lb) | Padded adjustable straps, mesh back panel, adjustable chest strap |
| Our 3D tiger backpack | 30 x 25 x 15 cm (12 x 10 x 6 in), 30 cm tall | 0.36 kg (0.8 lb) | Padded straps, mesh back panel, chest strap, side pocket for a water bottle |
| Our 3D astronaut backpack | 30 x 25 x 15 cm (12 x 10 x 6 in), 30 cm tall | 0.36 kg (0.8 lb) | Padded adjustable straps, mesh back panel, chest strap |
| Our excavator backpack for kids | 30 x 25 x 15 cm (12 x 10 x 6 in) | 0.36 kg (0.8 lb) | Zippered front pocket, mesh side pockets, top handle |
The four 30 x 25 x 15 cm bags measure 30 cm (12 in) on their longest side, so they suit a child whose back measures about 12 inches or more from just below the shoulders to the waist. The two dinosaur bags are smaller still, for a child who carries little more than a snack and a soft toy.
Kindergarten backpack FAQ
What size backpack is good for a kindergartener?
One that runs from about 1 to 2 inches below your child’s shoulders to the waist (AAP) and is no wider than your child’s back (Consumer Reports). Packed, it should weigh no more than 15% of your child’s body weight (AAP), or 10% (ACA, AOTA). L.L.Bean’s FAQ says its small packs, up to 20 liters, suit kids starting kindergarten.
Is a 17 inch backpack too big for kindergarten?
It is too big if it would hang more than 4 inches below your child’s waistline, the limit the AAP and the ACA set. Measure your child’s back from just below the shoulders to the waist. If that measurement is shorter than 17 inches, a 17 inch bag will hang below the waist, and if it is more than 4 inches shorter, the bag is too big by that limit.
What age is a 15 inch backpack for?
No health body we read ties a backpack size to an age. A 15 inch backpack suits a child whose back measures about 15 inches from 1 to 2 inches below the shoulders to the waist, whatever their age.
What size backpack for a 5 year old?
Measure the child rather than going by age. At 5, as at any age, the bag should reach from just below the shoulders to the waist and be no wider than the back.
Guidance checked on the AAP, ACA, AOTA and Consumer Reports websites on 19 October 2026. Read the AAP’s backpack safety advice on HealthyChildren.org for the full list.