"Age Ain't Nothing But a Number" received generally favorable reviews from critics. Many noted Aaliyah's vocal ability and praised the lyrical content. Aaliyah was credited for redefining R&B by blending her voice with Kelly's new jack swing. The album peaked at number 18 on the "Billboard" 200 and sold over three million copies in the United States. The album was certified Gold in Canada by Music Canada and Gold in the United Kingdom by the British Phonographic Industry (BPI). To date the album has sold over six million copies worldwide.