Free betting tools for MMA, UFC, NFL, NBA & all sports. Updated 2026.
How to Use This Betting Odds Calculator
Our free betting calculator suite gives you everything you need to make smarter bets. Whether you’re converting American odds to decimal, building a multi-leg parlay, locking in a hedge, or calculating the Kelly Criterion for optimal bet sizing — all six tools are right here in one place.
⇄ Odds Converter
The Odds Converter instantly converts between American (moneyline), Decimal, Fractional, and Implied Probability formats. Type into any field and all others update in real time. Enter a bet amount to see your exact profit and total payout. American odds show favorites as negative numbers (e.g. -110 means you risk $110 to win $100) and underdogs as positive (e.g. +150 means a $100 bet wins $150).
🔗 Parlay Calculator
A parlay combines multiple bets into one wager where every leg must win. The upside is much larger payouts — the downside is higher risk. Our parlay calculator supports up to 12 legs in American, Decimal, or Fractional format. It shows you the combined parlay odds, implied probability, total payout, and profit if all legs hit.
🛡 Hedge Bet Calculator
Hedging means placing a bet on the opposite side of your original wager to guarantee a profit or minimize a loss. This is most common when you have a live parlay that has hit several legs and want to secure profit before the final leg. Enter your original bet and the opposing odds to see exactly how much to hedge and what you will profit either way.
📊 No-Vig Fair Odds Calculator
Every sportsbook builds a vig (also called juice or hold) into their odds, meaning the implied probabilities of both sides add up to more than 100%. The No-Vig Calculator strips out the bookmaker’s margin to reveal the true implied probabilities and what the fair odds should be without juice. A typical -110/-110 line carries about 4.5% vig.
📐 Kelly Criterion Calculator
The Kelly Criterion is a bankroll management formula that calculates the mathematically optimal percentage of your bankroll to bet given your edge. Enter your bankroll, your estimated win probability, and the bet odds — the calculator shows the recommended bet size. Most professional bettors use Half Kelly (50% of the full Kelly recommendation) to reduce variance while still growing their bankroll efficiently.
⚡ Expected Value (EV) Calculator
Expected Value tells you whether a bet is profitable over the long run. If your true win probability is higher than the implied probability baked into the odds, you have a positive expected value (+EV) bet. Enter your odds, your estimated win probability, and bet size to see your EV per bet and projected profit over any number of bets.
Frequently Asked Questions
What is the difference between American, Decimal, and Fractional odds?
American (moneyline) odds show how much you win on a $100 bet. Positive odds (+200) show underdog profit on $100; negative odds (-150) show how much you must risk to win $100. Decimal odds show total return per $1 wagered including stake (e.g. 2.50 returns $2.50 per $1). Fractional odds (5/2) show profit relative to stake. All formats convey the same information — just in different ways common to different regions and sportsbooks.
What is implied probability in sports betting?
Implied probability is the win percentage a sportsbook’s odds suggest for a particular outcome. If a fighter is listed at -200, the implied probability is 66.7% (100/200+100). When your own estimated probability exceeds the implied probability, you have found a value bet. Most sharp bettors focus on finding edges where their estimated probability is higher than the implied.
What is a parlay bet?
A parlay (also called an accumulator) combines 2 or more individual bets into a single wager. All legs must win for the parlay to pay out. In exchange for this added risk, the potential payout is significantly larger than betting each leg separately. A 3-leg parlay at -110/-110/-110 pays out at roughly +595 American odds — about a 6x return on your stake.
When should I hedge a bet?
Hedging makes sense when you have a large pending profit locked in (usually on a parlay) and want to guarantee a win regardless of the final outcome. It also makes sense when circumstances change after you placed your original bet — for example, a key player gets injured. Use the hedge calculator to determine the exact amount to wager on the other side to either guarantee equal profit or at least break even.
How does the Kelly Criterion work?
The Kelly Criterion calculates the fraction of your bankroll to bet using the formula: f* = (bp – q) / b, where b is the net odds (decimal odds minus 1), p is your estimated win probability, and q is your estimated loss probability (1 – p). The Kelly formula maximizes long-term bankroll growth when your probability estimates are accurate. Most professionals use Half Kelly or Quarter Kelly to reduce volatility.