Free calculators / Odds converter
Odds converter
American and decimal odds describe the same price two different ways. Type a value in either notation and see both forms plus the implied win probability, all at once.
-110
1.9091
52.38%
The math
decimal = 1 + A/100 (A > 0) decimal = 1 + 100/|A| (A < 0) implied probability = 1 / decimal
The three formulas
American -> decimal
decimal = 1 + A/100 (A ≥ +100) decimal = 1 + 100/|A| (A ≤ −100)
Decimal -> American
A = (decimal − 1) × 100 (decimal ≥ 2.0) A = −100 / (decimal − 1) (decimal < 2.0)
Decimal -> implied probability
implied probability = 1 / decimal
+100 and −100 both describe the same fair coin-flip price (decimal 2.0) quoted from either side; converting decimal 2.0 back to American always returns +100, the standard convention.
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