There is no specific weight that allows a child to sit in the front passenger seat. Children ages 12 and under should ride properly restrained in the back seat of the vehicle.
Children should ride in an approved rear-facing car seat in the back seat from birth until age 2, or until they reach the height or weight limit of their specific car seat. Children should then ride in a forward-facing car seat with a harness until at least age 5 or until they reach the limits of the car seat. Then, they should ride in a belt-positioning booster seat until the seat belt fits properly.