At what age did you find out that santa is not real

I was around 5 when I found it out. One of my older friends told me that he saw some presents hidden in their parents bedroom, then next christmas we went every day hunting them and we found some, then I did it also at my home and found some, so then I realised it. But I did keep it as a secret for around 5-6 years and my parents thought that I still believed.