The break-even win rate at every common price

The break-even win rate is the share of bets that have to win at a given price for the total to come out level. It is the price's implied probability, and at -110 it is 52.4 per cent, not 50.

For a negative price it is the price divided by the price plus 100: 110 ÷ 210 at -110. For a positive price it is 100 divided by the price plus 100: 100 ÷ 250 at +150, which is 40 per cent.

The gap between 50 and 52.4 per cent at -110 is the margin, and it is why a coin-flip record at standard prices loses slowly rather than breaking even. Over a hundred bets it is the difference between level and about four and a half units down.

Which is where it goes wrong. Records are compared by win rate across very different prices, when a 45 per cent record at +150 is better than a 58 per cent record at -150.

What to do with it. Read every win rate next to the break-even rate for the price it was earned at. The distance between the two is the only part that says anything.

Work it out. The odds converter gives the implied probability of any price, and the expected value calculator shows what a different win rate does at that price.