The math behind a good bet, done for you: convert odds, price a parlay or a teaser, size a stake, hedge a position, strip the vig, and see whether a price is worth taking. No account needed.
Type odds in any format — American (-110), decimal (1.91) or fractional (10/11) — and read the other two plus the implied probability.
What a bet returns at a given price.
Combined odds and payout for 2-10 legs. Each leg's implied probability multiplies; the true chance is usually lower than it feels.
What a profit boost (or odds boost) is worth. Add the other side's price to see the fair win chance and whether the boosted bet is worth taking.
What a bet is worth on average at your probability. Positive EV is the whole game; the break-even is the implied probability of the price.
How much of the bankroll to risk given your win probability and the price. Half-Kelly (0.5) is the usual sane setting; full Kelly is a wild ride.
You hold a live bet and the other side is now available. How much to put on it to lock the same profit whichever way it goes.
The book's margin on a two-sided market, the fair (vig-free) price of each side, and the win rate you need at the listed price.
The moneyline a spread implies, from the historical scoring spread of the sport. Fair price and a typical vigged price.
Two books, two sides: is there a risk-free margin, and how to split the stake so both outcomes return the same.