The 8ml size lasts four months, using twice daily.Related ArticlesHow long does The Eyebrow and Lash Enhancing Serum take to dry?How often do I apply The Eyebrow and Lash Enhancing Serum?Is the The Eyebrow and Lash Enhancing Serum product unisex?How long will The Serum last?How long will The Retinol Serum last?