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