These drawings show how to measure and mark how far to insert an NG tube:
First, use 1 hand to hold the end of the tube to the tip of the child's nose. With the other hand, bring the tube to the bottom of their earlobe.
Next, use 1 hand to keep holding the tube at the child's earlobe. Then, use the other hand to bring the tube to the point midway between the child's "xiphoid process" (the end of their breastbone) and their belly button.
Mark the midway point between the breastbone and belly button on the tube with a marker or small piece of tape. This is how far the NG tube will be inserted.