What happens next?

How to measure a toddler for a bike
Gather the materials needed for taking your child's measurement.
You'll need measuring tape, a pencil, and a book or a ruler (or some other flat surface).
Have your child stand upright against a wall.
Their head should be facing straight ahead, and not tilted upwards or downwards, so you do not get a faulty measurement of their height. Make sure their feet are side by side, with both feet firmly on the floor and their heels touching the wall.