Winrate

When I talk about my winrate, I'm talking about how much money I have made over a given sample of hands. A small sample for when I'm talking about how many hands I've played vs a given player is like 500 or less. Any more, and I feel that I have a good sample on him and I can make fairly accurate reads.
However, when I'm talking about hands that I've played and I'm thinking about how I have done, the sample is much bigger. In a session, I can play between 1500 and 2000 hands (h). So I feel a good sample is 50,000h or 50kh. Here's how to calculate a win rate (WR).