Free Online Gambling Calculators

The best odds format depends on your region and preference. American odds (+150, -200) are popular in the US, decimal odds (2.50, 1.50) are used worldwide and easiest to calculate payouts, while fractional odds (3/2, 1/2) are traditional in the UK. Our Odds Converter makes it easy to switch between formats.

Parlay odds are calculated by converting all odds to decimal format and multiplying them together. For example, a 2-leg parlay at -110 (1.91) and +150 (2.50) equals 1.91 × 2.50 = 4.775 decimal odds, or approximately +378 American odds. Our Parlay Calculator does this automatically.

Expected Value (EV) measures the average return you can expect from a bet over time. A positive EV (+EV) bet is profitable long-term, while negative EV (-EV) bets lose money. The formula is: EV = (Win Probability × Profit) - (Loss Probability × Stake). Professional bettors focus on finding +EV opportunities.

The Kelly Criterion is a mathematical formula for optimal bet sizing that maximizes long-term bankroll growth. It calculates what percentage of your bankroll to wager based on your edge and odds. Many professional bettors use "half Kelly" or "quarter Kelly" for reduced variance.

Arbitrage opportunities exist when the combined implied probability across all outcomes is less than 100%. This happens when different sportsbooks have different odds on the same event. Our Arbitrage Calculator helps identify these opportunities and calculates the optimal stake for each outcome.

Closing Line Value measures whether you consistently beat the closing line (the final odds before an event starts). Positive CLV indicates you're getting better odds than the market settles at, which correlates strongly with long-term profitability. Sharp bettors track CLV to evaluate their betting skill.

Matched betting is a technique that uses free bets and bonuses from bookmakers to guarantee a profit. You place a back bet at a bookmaker and a lay bet at an exchange to cover all outcomes. The free bet or bonus provides the profit. Our Matched Betting Calculator handles the math for qualifying bets and free bet extraction.

SNR (Stake Not Returned) free bets only pay out the winnings if you win - the stake is not included in the return. SR (Stake Returned) free bets pay out both the stake and winnings if you win, making them more valuable. SR free bets typically retain 90-95% of value vs 70-85% for SNR. Always check your free bet terms to use the correct calculator.

A lay bet means betting against an outcome on a betting exchange. You act as the bookmaker, accepting someone else's back bet. If the selection loses, you win the stake minus commission. If it wins, you pay the liability. Lay bets are essential for matched betting and hedging strategies.