Ten calculators for thinking in probability.
A focused toolkit for understanding how sports markets price events. Everything runs locally - no accounts, no tracking, no picks for sale.
- Tools
- 10
- Data
- Client-side
- Cost
- Free
- Tracking
- None
Odds Converter
Translate American, Decimal, and Fractional odds with implied probability side-by-side.
Implied Probability
Convert any price into the probability the sportsbook is quoting.
Parlay Calculator
Combine legs to see the true combined odds, payout, and implied probability.
Bankroll Calculator
Translate your bankroll into rational unit sizes using flat or Kelly sizing.
Expected Value (EV)
Compare your estimated true probability against market odds to see edge per bet.
Payout Calculator
How much a winning stake returns at any American or decimal price.
Unit Tracker
Track a session of bets locally and see net units, ROI, and hit rate.
Line Movement Visualizer
Paste a price history and plot how a market moved over time.
ROI Estimator
Model long-run return on investment from your win rate and average odds.
Probability Comparison
Compare two probability estimates and translate the gap into a fair-odds delta.