Stop Guessing. Start Calculating.
Free betting calculators that show what your bets are really worth — parlays, expected value, fair odds, and more.
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 criterion. The math that separates sharp bettors from the rest.
Calculators & Tools
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Learn Betting Math
Practical guides to sharpen your edge — odds, probability, and expected value explained.
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.