What part of the shoulder do you use to figure out harness height? The outer edge of the shoulder or the taller part of the shoulder closer to the neck? Trying to figure out if my son has outgrown his carseat and it's difficult because the frame of a shoulder isn't level, it naturally slopes downward. So which part of the shoulder should be used to determine harness height? His harness is definitely above his outer shoulders but seems to curve downward like a backpack a tiny bit near his neck. But again, it's above the outer edge of the shoulders, so I don't know if I need a new seat for him or not. Please let me know if you are a cpst in the comments.
It's not an exact rule, unless your owner's manual details more specific guidance that you should follow. If not, the midpoint should be a reasonable guide. If the child is being uncomfortably squished down by the head wings of a car seat, it is probably adjusted too low.
If you are in doubt, adjust it a step higher for a forward-facing child or a step lower for a rear-facing child.
Combined with a properly adjusted harness (google "car seat pinch test" for a video) and chest clip at armpit level, the child will be secure even if you inadvertently make the harness one step higher than at the ideal shoulder level (forward-facing) or lower (rear-facing).
Can you please give the age and weight of the child and the brand and model of the car seat please?
