Free Betting Calculators

A set of fast, free betting calculators — no sign-up. Convert odds, size stakes, strip the vig, and check whether a bet is worth making. Then let PropPrizm do it for you across every book at once.

EV Calculator

Is this bet worth more than it costs? EV in dollars and percent, plus your edge over the price.

No-Vig (De-Vig) Calculator

Strip the book’s margin from a two-way market to get the fair probability and fair odds.

Kelly Criterion Calculator

Optimal stake for a bet, with full, half and quarter Kelly to control variance.

Odds Converter

Convert American, decimal, fractional and implied probability instantly.

Arbitrage Calculator

Check for a guaranteed-profit arb across two books and split your stake.

Parlay Calculator

Combine legs into one ticket: combined odds, payout and profit.

Hedge Calculator

Bet the other side to lock in profit or cut a loss — exact hedge stake.

Hold & Vig Calculator

How much the book keeps on a market: hold %, vig and fair probabilities.

Stop doing this by hand

These calculators do one bet at a time. PropPrizm's EV+ board runs the de-vig and EV math across every book, on every prop, live — and surfaces only the ones where a book is soft versus the market consensus.

See the EV+ board →

Frequently asked questions

Are these betting calculators free?

Yes — every tool here is free and needs no account. They run entirely in your browser.

What is the difference between these tools and PropPrizm’s EV+ board?

These calculators handle one bet at a time from numbers you enter. The EV+ board runs the same de-vig and EV math automatically across every sportsbook and every prop, live, and surfaces the bets where a book is soft versus the market.