Calculating period length

How do you calculate your period length?

Do you consider your period to be the length of active bleeding days only or the days after with minimal residual spotting / brown CM?

I always have 3 days of active bleeding and some months for 1-3 days after I will have minimal Brown “spotting” / small gushes of brown cm/old blood - not every month but it happens and I have always put in my app that my “period” lasts for 3 days but-

Should I be counting these days after the bleeding as a continuation of my period?

Or only count my period length for the days with actual bleeding?