How to Read Betting Odds: American, Decimal, Fractional
Learn how to read betting odds in American, decimal and fractional format, convert between all three, and turn any price into a probability and a payout.
How betting markets actually work
Lines & Limits
Est. MMXXVIlinesandlimits.comA journal of betting-market arithmetic
Bankroll Management: Staking, Variance and Ruin
Bankroll management for sports betting, with the math: unit sizing, flat vs percentage staking, the Kelly formula, and why overbetting a real edge ends in ruin.
Expected Value: The Only Betting Concept That Matters
Expected value betting explained with exact arithmetic: the EV formula, break-even probabilities, why +EV bettors lose for months, and where edges come from.
What Is the Vig? The Price of Every Bet, Explained
The vig is the fee built into every sportsbook price. How to calculate hold from any two prices, why parlays and futures cost more, and what you really pay.
Parlay Math: Why the Fun Bet Is the Expensive Bet
Parlay odds are multiplied decimal prices — and the margin multiplies too. Exact parlay math: three-leg payouts, hold by leg count, and same-game pricing.
From the tools desk
Odds converter & vig calculator
Convert American, decimal and fractional prices, read the implied probability, and strip the vig out of any two-way market to see the fair line.