A generated 24-hour movers snapshot plus three calculators for the math you actually use in prediction markets: convert Polymarket odds into probabilities, estimate expected profit, check whether a trade is +EV, and size risk. No signup.
Static snapshot of active prediction markets with the largest 24-hour odds moves, current price, volume, and liquidity.
Inputs: Public Polymarket API snapshot.
Outputs: Market question, odds, 24h change, volume, liquidity.
Open movers watchlist →
Convert Polymarket prices to implied probability — and your probability estimate to a fair share price. The first thing to do before any trade.
Inputs: Market price, or your probability %.
Outputs: Implied probability, fair price.
Open calculator →
Plug in market price, your probability, and stake. Estimate expected profit, downside, and EV with green/red verdicts before a trade becomes a plan.
Inputs: Market price, your probability %, bet amount.
Outputs: Expected profit, downside, EV in $ and %, take/skip verdict.
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Live taker fee rates by category, read from Polymarket's own market data, with the exact fee formula and a calculator for any price and size.
Inputs: Category, share price, number of shares.
Outputs: Fee in $, fee as % of cost, break-even probability.
Open fee calculator →
Turn a share price and resolution date into an annualized return, with fees and holding rewards — plus a live list of high-probability markets.
Inputs: Price, days to resolution, fee, your probability.
Outputs: Return if right, simple and compounded APY.
Open APY calculator →
Cost and profit of holding both sides of an event on Polymarket and Kalshi, with both fee formulas — plus live cross-exchange pairs.
Inputs: Two prices, fees, size, days to settlement.
Outputs: Total cost, guaranteed payout, profit, annualized return.
Open arbitrage calculator →
Convert American, decimal or fractional odds into implied probability and a Polymarket price, with the bookmaker margin removed.
Inputs: Odds for one or both sides, optional Polymarket price.
Outputs: Implied and fair probability, margin, edge vs Polymarket.
Open converter →
Bids, asks, spread and depth explained on a live order book, plus what a $100 to $50,000 market buy would cost right now.
Inputs: Live Polymarket order book.
Outputs: Spread, midpoint, depth, slippage by order size.
Open the guide →
Sell now, hedge with the opposite side or hold: profit, locked result and fees for your position.
Inputs: Shares, entry price, bid, opposite ask, fee.
Outputs: Sell, hedge and hold outcomes in $.
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The chance that all, any or none of up to six events happen — and the fair price of the combination.
Inputs: Up to six probabilities or prices.
Outputs: All / any / none probabilities.
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Turn a fed funds futures price into the odds of a 25 or 50 bps move at the next FOMC meeting, next to Polymarket's live Fed odds.
Inputs: Futures price, current rate, meeting day.
Outputs: Implied rate, change in bps, hike/cut odds.
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The chance Bitcoin or any coin ends above a price or inside a range by a date, seeded with the volatility implied by Polymarket's daily ladder.
Inputs: Price, days, volatility, target.
Outputs: Above / below / in-range chances.
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Turn a poll lead into a win probability, or a Polymarket price into the lead it implies — with the closest 2026 races.
Inputs: Poll lead, polling error, or a price.
Outputs: Win chances, matching lead.
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Do the odds add up to 100%? Get the sum, the vig and fair probabilities, and see how Polymarket's winner markets add up today.
Inputs: Prices of every outcome.
Outputs: Sum, overround, fair probabilities.
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Turn two Elo ratings into win chances, a fair price and American odds — or a Polymarket game price into the Elo gap behind it.
Inputs: Two ratings, home advantage, or a price.
Outputs: Win chances, fair price and odds, Elo gap.
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Simulate thousands of bankrolls: how often a stake size halves your bankroll, the median result and the Kelly stake.
Inputs: Your probability, price, stake, number of bets.
Outputs: Chance of ruin, median bankroll, Kelly stake.
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Read a "by October 31 / by December 31" ladder: the chance for each period, the monthly chance it implies, time decay if nothing happens, and mispriced ladders.
Inputs: Deadlines and their Yes prices.
Outputs: Chance per period and per month, drift price, ladder check.
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What a market buy really costs: the spread, the walk up the order book, the taker fee and the break-even probability that leaves you.
Inputs: Bid, ask, order size, fee rate, depth.
Outputs: Average fill, slippage, break-even chance.
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How far a real edge can grow a bankroll and how rough the ride is: median and 10th–90th percentile outcomes, with full, half and quarter Kelly.
Inputs: Bankroll, bets, price, your probability, stake.
Outputs: Log growth, percentile bankrolls, drawdown odds.
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One printable table: every common price as a chance, profit on $100, American, decimal and fractional odds, and break-even after fees.
Inputs: None — print it or keep it open.
Outputs: Price ↔ probability ↔ odds, fee break-even, sportsbook lines.
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Twelve checks before and after a prediction market trade — rules, fees, spread, size, exits — each linked to the tool that answers it. Printable.
Inputs: None — tick the boxes or print it.
Outputs: A one-page pre-trade and post-trade routine.
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How Polymarket settles a market on one printable page: the UMA steps and their timing, real payout times by category, and the edge cases (clarifications, 50-50, "Other").
Inputs: None — print it or keep it open.
Outputs: Process, timing, dispute rates, edge cases.
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Bids, asks, spread, midpoint, depth and maker/taker on one printable page, with an example book and what a market buy of $100 to $10,000 really costs.
Inputs: None — print it or keep it open.
Outputs: Terms, example fills, slippage.
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Score your probability forecasts (and Polymarket prices) with the Brier score and log loss.
Inputs: Forecasts and outcomes, one per line.
Outputs: Brier score, skill vs 50%, log loss.
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Up or Down, crypto price ladders, tweet counts, temperatures, Fed decisions, multi-outcome and deadline markets — with live examples and their rules.
Inputs: —
Outputs: Plain-English guides with live markets.
Open the guides →
UMA proposals, the 2-hour challenge window, disputes and payout times, from Polymarket's documentation.
Inputs: —
Outputs: Step-by-step resolution timeline.
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A free Kelly criterion calculator for prediction-market bet sizing. Includes full Kelly plus 1/2 and 1/4 Kelly so the output is useful even when your edge estimate is uncertain.
Inputs: Bankroll, your edge %, decimal odds.
Outputs: Optimal bet size in $ and % of bankroll.
Open calculator →
The usual workflow is: a market catches your eye in the biggest movers watchlist → use the probability calculator to compare its price to your view → use the Polymarket profit calculator to check expected profit and edge → use the Kelly calculator to size risk. Watchlist first, trade only after the thesis is clear.
The Polymarket odds converter is the fastest way to translate a YES price into implied probability. A 62¢ contract means the market is pricing roughly a 62% chance. If your estimate is 70%, the same tool converts that view back into a fair 70¢ price before you check EV or sizing.
Polymarket prices are direct probabilities, which makes the math cleaner than traditional sportsbooks but also more unforgiving. There's no vig hiding your edge — but there's also no margin for sloppy sizing. These calculators handle the formulas so you can focus on the question that actually matters: is your probability estimate better than the crowd's?
What is the Polymarket odds converter?
It is the implied probability calculator in this toolkit: enter a Polymarket YES price like 0.62 and it returns 62% implied probability, or enter your own probability and it returns a fair price.
Which tool should I open first?
Start with the biggest movers watchlist if you need ideas, then use the odds converter, EV calculator, and Kelly calculator to check probability, edge, and risk size.
For more, read our Polymarket trading strategies guide, the risk management guide, or the portfolio management guide.