Quick calculators for prediction-market traders. Work out your fees, odds, payout, edge, and position size in seconds. No signup, nothing leaves your browser.
None of those? Everything below is grouped by the job it does. And if the question is really “am I any good at this?”, no calculator can answer it: that needs your actual history, which is what the free Trade Report is for.
Yes, every calculator here is free with no signup. They run entirely in your browser, so nothing you enter is uploaded or stored.
Which calculator should I use to size my bets?
Start with the position size calculator to get a Kelly-based stake from your edge, then use the risk of ruin calculator to check that stake survives your variance. The bankroll growth simulator projects where consistent sizing gets you over time.
How do I know if my trading edge is real?
Use the edge significance calculator: enter your trades, wins, and average price to get a statistical verdict on whether your win rate is skill or variance. The trades-to-prove-edge calculator shows how large a sample you need, and the variance simulator shows how much a real edge still swings.
Can these replace analyzing my full trade history?
No. The calculators are quick, single-scenario tools. To analyze your whole record, by price band, category, and behavior, upload your Kalshi CSV to the Trade Report and Edge Lab, which is also free.