Betting & Odds Tools

Free betting and odds calculators that run entirely in your browser — odds format converter, parlay payout, Kelly stake, no-vig/de-vig fair odds, hold and margin, expected value, break-even rate, hedging, arbitrage, free-bet value, round-robin and middles. Pure math, no accounts, no real-money handling.

🔁

Odds Converter

Convert betting odds between American (moneyline), Decimal (European), Fractional (UK), and implied probability all at once, in any direction.

🎟️

Parlay / Accumulator Payout Calculator

Multiply the odds of every leg in a parlay (accumulator) and a stake to get combined odds, total payout, profit, and parlay implied probability.

📊

Kelly Criterion Stake Calculator

Find the optimal Kelly bet size from your win probability and the offered odds, with full, half, and quarter-Kelly fractional staking options.

⚖️

No-Vig / Fair Odds Calculator

Strip the bookmaker margin (vig) from a 2-way or multi-way market to reveal fair no-vig odds and true implied probabilities for each outcome.

🏦

Bookmaker Hold / Vig Calculator

Calculate the hold (vig, juice, margin) baked into a market from its prices: hold% = sum of implied probabilities minus 100%.

💡

Expected Value (EV) Bet Calculator

Compute a wager's expected value and EV% from your true win probability and the offered odds: EV = stake × (p × decimal − 1).

🎯

Break-Even Win Rate Calculator

Find the minimum win percentage you must hit at any odds just to break even, plus the win rate needed for a target ROI and your margin vs it.

⚖️

Hedge / Cash-Out Calculator

Find the hedge stake on the opposite outcome that locks in an equal guaranteed profit whichever side wins, plus your total outlay and locked ROI.

🔁

Arbitrage (Sure Bet) Calculator

Detect a 2- or 3-way arbitrage across books and split a budget into per-outcome stakes that guarantee the same return, with the sure-bet profit and ROI.

🎁

Free Bet / Bonus Bet Value Calculator

Estimate the real cash value of a stake-not-returned free bet, as raw expected value and as a guaranteed conversion rate when you hedge the other side.

🔗