Not that simple
Prince Dragon gave you the mathematically "correct" Hi-Lo indices.
Bit that is not the whole story. Increasing profits and reducing variance are important.
Like the redoubtable Arnold Snyder, I suggest taking "Even-Money" on your Blackjacks.
It is a very very low-cost "cover play" that actually helps to reduce your 'variance'
I take "even money" at all positive counts and sometimes, as when I am winning, down to T.C. = -1