You should adjust the infant car seat's harness straps every single time you buckle your child in. A proper fit is critical for safety, as loose straps can't effectively restrain your child in a crash. The harness should be snug enough that you cannot pinch any excess webbing at the child's shoulder.
A common mistake is leaving the straps loose for comfort, but this creates a dangerous gap. In a collision, a child can slip through loose straps (a phenomenon called "submarining") or be thrown against the interior of the vehicle. The correct tightness ensures the crash forces are distributed across the strongest parts of the child's body—the shoulders and hips.
Here’s a quick guide for the proper harness position and tightness check:
| Adjustment Checkpoint | Correct Position/Tightness |
|---|
| Harness Height | At or just below the infant's shoulders for rear-facing seats. |
| Chest Clip | Level with the infant's armpits. |
| Pinch Test | You should not be able to pinch a horizontal fold of the harness strap at the shoulder. |
| Straps to Body | Snug against the body with no slack. You can fit only one or two fingers between the strap and the child's collarbone. |
| Bulky Clothing | Avoid thick coats. Place blankets over the harness after buckling. |
As your baby grows, you'll also need to make larger, less frequent adjustments. You must raise the harness straps to the next slot when the child's shoulders are level with the next higher slot. Always consult your specific car seat manual, as models can vary. The five-point harness is your primary safety system; its correct adjustment is non-negotiable.
