Randron Sports mark: a chalked letter A inside a square

Notes on odds, house percentages and the arithmetic behind the games.

Odds conversion table

The same price written three ways, with the probability each notation implies. Implied probability is derived directly from the price: a minus price divided by itself plus a hundred, a plus price as a hundred divided by the price plus a hundred.

American, decimal and fractional prices with the probability each implies.

AmericanDecimalFractionalImplied probability
-4001.251/480.0%
-3001.331/375.0%
-2501.402/571.4%
-2001.501/266.7%
-1501.672/360.0%
-1251.804/555.6%
-1101.9110/1152.4%
+1002.001/150.0%
+1102.1011/1047.6%
+1252.255/444.4%
+1502.503/240.0%
+2003.002/133.3%
+2503.505/228.6%
+3004.003/125.0%
+4005.004/120.0%
+7508.5015/211.8%
+100011.0010/19.1%

Adding the implied probabilities of both sides of a two-way market gives a total above one hundred per cent; the excess is the margin described in the entry on the vigorish.