calculating p/l..something missing?

In my demo account from think or swim i purchased 50,000 (lots, I believe) gbp/usd at 1.6336. its now trading at 1.6341, but in my according to my think or swim demo account "monitor screen" i have a loss at $25. I'm confused how this got calculated? I wonder if the demo account is not exacly the same as a real account...

u bought $50,000 usd worth of gbp/usd. not lots. for fx 1 lot = 100,000 usd worth.

u're prob seeing bid price...when you bought you paid the offer. so add the spread.. when they calc your p/l it could be based on mid or bid price.