Free sports betting calculators.
Parlay payouts, odds conversion, +EV, no-vig, and Kelly. Same math. No signup.
Why Calculate?
Know Your Edge
Every sportsbook builds a margin into the odds. Our no-vig and +EV calculators strip it away so you see the real probability.
See Every Format
American, decimal, fractional, implied probability — enter once, convert instantly. No mental math, no mistakes.
Stack Your Bets
Build parlays, find arbitrage, size your bankroll with Kelly. The same math, in one place.
Calculators & Tools
Pick one, enter your odds, and get instant results.
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Which Calculator Do I Need?
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Learn Betting Math
Odds, parlays, expected value, and how to read a prediction-market ¢.
Frequently Asked Questions
What is a betting calculator?
A betting calculator is a tool that converts odds between formats (American, decimal, fractional) and computes payouts, implied probability, and expected value for single bets or parlays.
How do I convert American odds to decimal?
For positive American odds, divide by 100 and add 1 (e.g., +150 = 2.50). For negative odds, divide 100 by the absolute value and add 1 (e.g., -200 = 1.50). Our odds converter does this instantly.
What does +EV mean in sports betting?
Positive expected value (+EV) means a bet will be profitable over many repetitions. It occurs when the implied probability from the odds is lower than the true probability of the outcome.
How do I calculate a parlay payout?
Multiply the decimal odds of each leg together, then multiply by your stake. For example, two legs at 2.00 each: 2.00 x 2.00 = 4.00 combined odds, so a $10 bet pays $40.
What is the vig in sports betting?
The vig (or juice) is the sportsbook's built-in commission. It inflates the odds so the implied probabilities of all outcomes sum to more than 100%. Our no-vig calculator removes it to reveal fair odds.
What is Markets on CalcMyBets?
Markets compares the same game on Kalshi and Polymarket. We only name the cheaper book when the ¢ still wins after the taker fee. We do not pick a winner. Skip means the gap is noise.
How do I use a betting odds calculator?
Enter your odds in any format — American, decimal, or fractional — and add your stake. The calculator instantly shows your payout, profit, and implied probability. For multiple selections, use the parlay calculator; to see the fair price with the sportsbook's vig removed, use the no-vig calculator. Every tool is free and needs no signup.