ROI Calculation

Okay guys I am trying to figure out how to manually calculate ROI as SNG Tracker does not support Full Tilt Poker.

Anyways what I found in the FAQ was this calculation to use...

(Total Prizes Won - Total Buyins Paid) / (Total Buyins) = ROI Percentage

So say for example...

$2600 (Prizes) - $1100 (buyins) / 100 Buyins = 15% ROI?

Correct?

If someone could confirm or deny my calculations it would be greatly appreciated. Preferably a long time poster who knows for sure these calculations.

SuitedChef