I use the “Rqrd Odds” field of the WagerMate reports to make conditional bets with my ADWs. In essence, the Required Odds determine the lowest odds I’m willing to take.

Here’s how WagerMate calculates that number.

1) For each dollar bet at post time odds of X/Y, the payout will be (1 + X/Y) dollars. A bet at 6/1 odds will return about $7 for each $1 bet (1 + 6/1), or $14 for a $2 bet.

2) WagerMate calculates a probability of winning for each horse, the “Win %” field in the reports. If the probability of winning is 19%, then we’d expect our horse to win 19 out of 100 such races.

Imagine a $2 bet on each of those 100 (hypothetical) races — for a total of $200 bet. We expect to win $14 in each of 19 of those races, for a total return of $266.

That’s an ROI of 33% (a profit of $66 divided by an investment of $200).

3) The expected payout, in dollars for each dollar bet, is

Expected Payout per Dollar = (1 + X/Y) * (Win %)

In our example:

Expected Payout per Dollar = (1 + 6/1) * (0.19) = 1.33

4) WagerMate assumes we want an ROI of at least 20%. That’s an Expected Payout per Dollar of 1.20.

So 1.20 = (1 + X/Y) * (Win %)

Rearrange that to get the Required Odds: X/Y = [ 1.20 / (Win %)] – 1

For our example: [1.20 / 0.19] – 1 = 5.32

WagerMate reports that as 5/1.