Effective Stack

math

The smaller of two stacks in a heads-up pot — the most that can be won/lost.

Always think in effective stacks, not your own stack. SPR is computed off effective stack, not yours.

See also

Equity
Your statistical share of the pot, expressed as a winning probability.
EV
The average profit/loss of a play over infinite repetitions.
Implied Odds
Pot odds adjusted for expected future bets if you hit your draw.
Outs
Cards remaining in the deck that improve your hand to a winner.