Tools
Odds & ROI Calculator
Convert any odds format, size your edge against the market, and build parlays with fair-value grounding.
Converter
Odds Converter
American
-110
Decimal
1.909
Implied
52.38%
Edge
ROI Calculator
Fair Odds
-122
1.818 dec
Market
-110
1.909 dec · 52.38%
Edge
+2.62%
Exp. ROI
+5.00%
1/4 Kelly
1.38%
Full Kelly = 5.50%. Most bettors should use quarter-Kelly or less to survive variance.
Parlay
Parlay Calculator
Combined American
+264
Combined Decimal
3.645
Implied Probability
27.44%
Profit
$26.45
Payout
$36.45
How it works
Fair Odds
Our model outputs a true probability. Converting that to American odds gives you the fair line — the price at which the bet has zero expected value.
Edge & ROI
When the market line is worse than fair, you have an edge. Projected ROI tells you how much profit you expect per dollar risked over the long run.
Kelly Stake
The Kelly criterion sizes bets to maximize log-wealth. We show full Kelly and quarter-Kelly — most bettors should size down to manage variance.