Free calculators
Prediction market tools
Run the numbers before you trade. Free, instant, and nothing is stored — just the figures that actually affect your decision.
Profit & payout calculator
Enter a contract price and a stake to see how many shares you get, your total payout, profit if you win, loss if you don’t, and ROI — for either side.
Odds & probability converter
Convert between contract cents, implied probability, decimal, fractional and American odds. Edit any format and the rest update instantly.
Kelly criterion calculator
Find the bankroll-optimal stake for a trade from your edge — full, half or quarter Kelly — with the stake in dollars and contracts.
Expected value (EV) calculator
See whether a trade is worth making: expected value, expected ROI and your edge per contract from a price, your probability and a stake.
Bankroll & position size
Turn your bankroll and a risk percentage into a unit size in dollars and contracts, with a quick read on how much cushion it gives you.
Arbitrage calculator
Check whether buying both sides of a market locks in a guaranteed profit, and how to split your budget across the two legs.
Fee calculator
See what fees really cost: net profit, true break-even win rate and ROI after a per-contract or percentage fee on any platform.
No-vig & fair odds
Strip the bookmaker margin out of two-sided odds to reveal each outcome’s fair, no-vig probability and price.
Parlay calculator
Combine several markets into one parlay and see the true combined odds, payout and profit — remembering every leg has to hit.
Hedging calculator
Work out how much of the opposite side to buy to lock in a guaranteed profit or loss on a position that has moved.
Profit & loss calculator
Selling before settlement? See your realised profit or loss and return from buying at one price and selling at another.
Break-even win rate
Find the win rate a price requires to break even, then add your own win rate to see whether there is an edge.
Average entry calculator
Bought in at several prices? Get your blended average entry, break-even and unrealised profit or loss.
Tax estimator
A rough federal ballpark on a year’s net profit. Enter your profit and marginal rate — general guidance only, not tax advice.
Spot a market quoted in odds you don’t recognise? Drop it into the converter to get the implied probability, then take that price to the profit calculator to size your position and see the payout. Two steps, real numbers.
Why run the numbers first
On a prediction market, the price you pay is the probability you are accepting — and the payoff is fixed: every contract settles at $1 if you are right and $0 if you are wrong. That makes the maths simple, but it is easy to misjudge a position in your head. A 90¢ Yes share only returns about 11¢ of profit per dollar risked, so a single loss wipes out several wins; a 30¢ share triples your money but comes in less than a third of the time. Seeing those figures before you trade keeps your expectations honest.
The profit calculator handles position sizing: enter a price and a stake and it returns your shares, total payout, profit, loss and ROI for either side. The odds converter handles translation: paste a market quoted in decimal, fractional or American odds and read off the implied probability, then take that to the calculator. Neither tool stores anything — the numbers stay in your browser.
Now find the right platform
You've run the numbers — see which regulated exchange fits the markets you want to trade.
Independent · No platform pays for placement · 18+ only