How to Measure Your Kid
for the Right Bike
Forget age charts. The two numbers that matter are your child's inseam and height. Take 60 seconds, get them right, and they'll ride confidently from day one.
Show Me HowSize matters more than age
Confidence to Ride
A bike that's too big is scary. Kids who can't touch the ground freeze, fall, and quit. The right size lets them learn fearlessly.
Safety First
Bikes that are too small or too big lead to poor control, awkward braking, and tipping. Proper sizing keeps small riders safer on every turn.
Faster Progression
When a bike fits, kids progress quickly — pedalling, balancing, and steering naturally. They graduate to the next size sooner.
Two measurements. Sixty seconds.
Measure their inseam
Inseam (the length from crotch to floor) is the single most important number for sizing. It tells you exactly which wheel size your child can stand over confidently.
What you'll need: a hardcover book, a tape measure, and a wall.
- Stand barefoot, back against a wall, feet about 15 cm apart.
- Place the book between their legs, spine-up, snug against the crotch (mimicking a saddle).
- Mark the top of the book on the wall.
- Measure from the mark down to the floor — that's the inseam.
Measure their height
Height is the secondary check — useful for fine-tuning between two sizes and confirming your inseam result. Measure the same way: shoes off, back to the wall, eyes forward.
Pro move: place a hardcover book flat on their head, parallel to the floor, and mark the wall where it touches.
Measure both numbers in centimetres. Most kids' bikes are sized by wheel diameter (in inches), but inseam in cm is more precise for matching them to a frame.
Match the inseam to the wheel size
| Age (approx.) | Height | Inseam | Wheel Size | Bike Type |
|---|---|---|---|---|
| 2 – 3 years | 85 – 100 cm | 30 – 38 cm | 12" | Balance bike |
| 3 – 5 years | 95 – 110 cm | 38 – 47 cm | 14" | First pedal bike |
| 4 – 6 years | 105 – 120 cm | 45 – 55 cm | 16" | Pedal bike |
| 6 – 8 years | 115 – 135 cm | 55 – 65 cm | 20" | Geared kids' bike |
| 8 – 11 years | 130 – 150 cm | 63 – 75 cm | 24" | Junior mountain / hybrid |
| 11+ years | 145 cm + | 72 cm + | 26" | Adult-style small frame |
Inseam beats age every time. If your child's inseam falls between two sizes, go with the smaller one for confidence — they'll grow into the next quickly.
Find your child's size
Enter their inseam — we'll tell you the right wheel size.
Six things to check when they sit on it
Common questions
Should I buy a bigger bike so they can grow into it?
What if my child's inseam falls between two sizes?
Is age a reliable way to pick a size?
How often should I re-check the size?
Balance bike or training wheels first?
Not sure? We'll help you size it.
Send us your child's inseam and height — a Grow Bike specialist will recommend the perfect frame, and we'll swap it for free when they outgrow it.
How to Measure Your Kid
for the Right Bike
Forget age charts. The two numbers that matter are your child's inseam and height. Take 60 seconds, get them right, and they'll ride confidently from day one.
Show Me HowSize matters more than age
Confidence to Ride
A bike that's too big is scary. Kids who can't touch the ground freeze, fall, and quit. The right size lets them learn fearlessly.
Safety First
Bikes that are too small or too big lead to poor control, awkward braking, and tipping. Proper sizing keeps small riders safer on every turn.
Faster Progression
When a bike fits, kids progress quickly — pedalling, balancing, and steering naturally. They graduate to the next size sooner.
Two measurements. Sixty seconds.
Measure their inseam
Inseam (the length from crotch to floor) is the single most important number for sizing. It tells you exactly which wheel size your child can stand over confidently.
What you'll need: a hardcover book, a tape measure, and a wall.
- Stand barefoot, back against a wall, feet about 15 cm apart.
- Place the book between their legs, spine-up, snug against the crotch (mimicking a saddle).
- Mark the top of the book on the wall.
- Measure from the mark down to the floor — that's the inseam.
Measure their height
Height is the secondary check — useful for fine-tuning between two sizes and confirming your inseam result. Measure the same way: shoes off, back to the wall, eyes forward.
Pro move: place a hardcover book flat on their head, parallel to the floor, and mark the wall where it touches.
Measure both numbers in centimetres. Most kids' bikes are sized by wheel diameter (in inches), but inseam in cm is more precise for matching them to a frame.
Match the inseam to the wheel size
| Age (approx.) | Height | Inseam | Wheel Size | Bike Type |
|---|---|---|---|---|
| 2 – 3 years | 85 – 100 cm | 30 – 38 cm | 12" | Balance bike |
| 3 – 5 years | 95 – 110 cm | 38 – 47 cm | 14" | First pedal bike |
| 4 – 6 years | 105 – 120 cm | 45 – 55 cm | 16" | Pedal bike |
| 6 – 8 years | 115 – 135 cm | 55 – 65 cm | 20" | Geared kids' bike |
| 8 – 11 years | 130 – 150 cm | 63 – 75 cm | 24" | Junior mountain / hybrid |
| 11+ years | 145 cm + | 72 cm + | 26" | Adult-style small frame |
Inseam beats age every time. If your child's inseam falls between two sizes, go with the smaller one for confidence — they'll grow into the next quickly.
Find your child's size
Enter their inseam — we'll tell you the right wheel size.
Six things to check when they sit on it
Common questions
Should I buy a bigger bike so they can grow into it?
What if my child's inseam falls between two sizes?
Is age a reliable way to pick a size?
How often should I re-check the size?
Balance bike or training wheels first?
Not sure? We'll help you size it.
Send us your child's inseam and height — a Grow Bike specialist will recommend the perfect frame, and we'll swap it for free when they outgrow it.
To install this Web App in your iPhone/iPad press
and then Add to Home Screen.
