Sports Betting Calculators

Odds, payout, implied probability, EV

Supports American, Decimal, Fractional. Add your “true win chance” to compute EV.

Odds type

Odds

Tip: include + or - for American odds.

Stake

Your true win probability (%)

Optional — used for EV + Kelly (in the Kelly tab too).

Vig / juice adjustment (optional %)

If you want a rough “after vig” payout estimate, enter your effective fee here.

Bankroll (optional)

Used for quick “risk %” display.

Parlay calculator

Enter 2–8 legs. Use decimal odds for the cleanest math; we’ll convert from American too.

Stake

Leg odds input

For parlays, overall probability is the product of implied probabilities (assuming independence). That’s a simplification — but it’s the standard calculator approach.

Hedge calculator (lock profit / reduce risk)

You already placed Bet A. Now add Bet B on the other side and see hedge stake & outcomes.

Bet A stake

Bet A odds (American)

Bet B odds (American)

Hedge goal

Assumes mutually exclusive outcomes (A wins OR B wins). If you’re trying to “middle” a spread/total, you can still use this to size a hedge — but real middle outcomes can produce extra win/loss states.

Arbitrage calculator (two-way)

Enter best odds for each side from different books. See if an arb exists and stake splits.

Outcome A odds (American)

Outcome B odds (American)

Total amount to invest

Fees / friction (optional %)

Optional: to roughly account for bonuses, withdrawal fees, etc.

Arb exists when (1/decA + 1/decB) < 1. This assumes two mutually exclusive outcomes (no draw).

Kelly criterion sizing

If you have an edge (true probability > implied), Kelly suggests a bankroll fraction.

Bankroll

Use fractional Kelly

Odds type

Odds

Your true win probability (%)

Max bet cap (% of bankroll)

Optional safety guardrail.

Full Kelly can be aggressive. Fractional Kelly is usually safer in sports betting due to estimation error.