Hi, I just want to share you my thoughts about this. The calculation on your Steemit account makes use of the current STEEM value in USD to compute for SP or Steem Power. And SBD is treated as $1 as it should be in the Steem whitepaper. So the computation would be:

(Steem Price X Steem Tokens) + (Steem Price X Steem Power) + ($1 X SBD) = Your Steemit Account Value in USD

You may verify it using your account details. :)

Busy.org has a more accurate display of your account value in USD using the current market value of Steem and SBD. You may check yours at https://busy.org/@replacethiswithyourusername/transfers. Just replace with your username after the @ sign.