Free sports betting calculators
Twelve calculators that run the same math as our tools: EV, no-vig with five devig methods, Kelly, arbitrage, hedge, parlay, bonus conversion, implied probability, hold, pick'em break-even, exchange fees and odds conversion. Every result shows its working.
Convert the odds
Read any price as a probability.
Implied probability calculatorBreak-even win % for any price; add the other side for the no-vig fair.Odds converterAmerican, decimal, fractional, probability, HK, Malay, Indonesian.
Remove the vig
Find the fair price inside a market.
No-vig fair odds calculatorFair odds with five devig methods side by side, 2- to 6-way markets.Hold (market vig) calculatorA market's hold, its band (arb, near-arb, low, standard) and fair prices.
Price the edge
EV, fees, parlays and pick'em entries.
Expected value (EV) calculatorEV, edge and Kelly from a fair %, fair odds or a two-sided market with the vig removed.Parlay calculatorCombined odds and payout for up to 12 legs, plus EV from fair %.Pick'em break-even calculatorPer-leg break-even for PrizePicks, Underdog, Dabble and more; entry EV.Exchange and prediction-market fee calculatorNet price after Kalshi, Polymarket, ProphetX, Novig and exchange fees.
Size and manage
Stakes, hedges, arbs and bonuses.
Kelly criterion calculatorStake size from your edge: full, half, quarter Kelly and a bankroll cap.Arbitrage calculatorLocked return and stake split for 2- or 3-way arbs, net of exchange fees.Hedge calculatorStake to lock equal profit or break even on an open bet.Bonus bet conversion calculatorHedge a free bet or profit boost into locked cash; conversion %.
Why these calculators
Every calculator here uses the same math engine as The Sports King's odds tools, and a test checks the two agree to nine decimal places. Each result shows the formula with your numbers in it, so you can check the working rather than trust a black box.
- Five devig methods, not one: multiplicative, additive, power, Shin and probit side by side, with the solved constant for each.
- Exchange and prediction-market fees applied where you bet (Kalshi, Polymarket US, Novig, ProphetX, BetOpenly and others), from their published schedules.
- Pick'em break-evens from the PrizePicks, Underdog, Dabble, Betr and ParlayPlay payout tables.
- Shareable links: every input is in the URL, so a link reproduces your exact calculation.
- American, decimal, fractional or probability input, on phone or desktop, light or dark.
The calculators show math only. The Sports King doesn't take bets.
Frequently asked questions
Are the calculators free?
Yes, free with no account or sign-in.
Do the calculators match your tools?
Yes. They run the same formulas as the engine behind the odds screen and +EV finder, and an automated test compares them on tens of thousands of inputs.
Can I share a calculation?
Yes. Every input is saved in the page address; use Copy share link and anyone who opens it sees the same numbers.
Which odds formats are supported?
American, decimal, fractional and implied probability. Switching formats converts the prices you have already typed.