ExSpade Start With the Math ↗
ExSpade /

The Odds Lab

Read the Price. Test the Assumption.

Start with a payout. Then separate what the odds imply from what you believe will happen.

01 / Interactive Workbench

Decode the Odds.

Change either number.
The math updates as you type.

Implied ProbabilityBreak-Even Point
52.38%

The win rate needed to break even.

0%50%100%

A price does not tell you the true chance of winning.

Decimal Odds1.91
Profit if You Win$9.09
Return if You Win$19.09

Return includes the stake. Losing means losing the stake. No fees included.

Understand Expected Value ↗

02 / Expected Value

What If Your Estimate Is Wrong?

This is your assumption, not an ExSpade prediction. The tool cannot verify it.

Expected Net Result per Bet−$0.45

An average loss under your assumption.

Break-Even Probability52.38%
Expected Return on Stake−4.55%

50% × $9.09 − 50% × $10.00 ≈ −$0.45

No pushes, fees or partial settlements. A positive modeled result only follows from the probability you entered.

03 / Two-Outcome Market

Where Does the Margin Sit?

Use opposing prices for the same market, time and settlement rules. Outcomes must be mutually exclusive and exhaustive, with no draw or push.

Overround4.76%

The two implied probabilities add to more than 100%.

Normalized A50.00%
Normalized B50.00%

Normalization divides each implied probability by their sum. It is one mathematical adjustment, not a forecast or the sportsbook’s realized hold.

The Arithmetic

Positive American odds A become decimal odds 1 + A/100. Negative odds A become 1 + 100/|A|. Break-even probability is 1 ÷ decimal odds.

Expected net result = assumed win probability × profit if won − loss probability × stake. Overround = the sum of both implied probabilities − 1.

Read the Expected Value Guide →