How to Calculate Conversion Rate

[Sirazam Manira]

If a user can only convert once
Now imagine we owned a second site — Roger's Monthly Gear Box. Our site sells a subscription for a monthly delivery of robot parts. A user could come back multiple times, but once they purchase a subscription, they won't convert again.

Let's look at an example user's behavior:
Session 1:  User came to the site for the first time to explore the service.  No conversion.
Session 2: User subscribed to our monthly GearBox service-- this is our conversion!
Session 3: User came back to read blog articles and poke around. 
Our user here can't convert each time they visit the site. So instead of looking at the number of sessions, we need to measure conversion success by the number of visitors:
              unique orders             unique users
                     1                                1
              (1orders/1unique users)=100% conversion rate
To figure out our website's conversion rate, we would take the number of unique orders and divide it by the number of unique users.
Calculating Conversion Rate by Unique Users:
               unique orders             unique users
                    500                          2500
      (500orders/2500unique users)=20% conversion rate