The first calibration engine for prediction markets. We recorded what half a million Kalshi prices were worth — then checked what really happened.
Every other tool helps you place a bet. Priors tells you what the bet — and the bettor — is actually worth.
When Kalshi prices something at 30¢, does it happen 30% of the time? See the truth by category, price, and horizon.
Explore the data →Upload your trades. Get your Brier score, calibration curve, and the real reason you're up or down — fees included.
Get your report card →Where the market is soft, where it's sharp, and the first measured spread on Kalshi's head-to-head markets.
Read the findings →Bet $100 on final-hour weather longshots and history paid back about $5. Roughly 12× overpriced.
Buying both sides of a match costs ~101¢ per guaranteed 100¢ — a quarter of a sportsbook's cut.
“Sure thing” favorites priced at 95¢ the night before resolve just 90.7% of the time.
One game spawns forty correlated markets. Every other accuracy dashboard counts them as forty observations — so their error bars lie. We cluster by event and bootstrap over games. It’s the only calibration you can trust.