Sample Size & Confidence Calculator
Is your win rate skill or luck? Find out how many bets you need.
Enter as a percentage (e.g., 56 for 56%)
Leave blank if you don't track CLV
Understanding Sample Size & Statistical Significance
Statistical significance tells you whether your betting results are likely due to genuine skill or could simply be explained by random variance. A winning record over 50 bets means far less than the same record over 500 bets.
The confidence interval gives a range where your true win rate likely falls. If this entire range is above the break-even probability, your edge is statistically significant at that confidence level.
Standard Error = √(p × (1 - p) / n)
Confidence Interval = Win Rate ± (z × SE)
Required Sample Size = (z / margin)² × p × (1 - p)
CLV (Closing Line Value) provides additional evidence. Positive CLV means you're consistently beating the closing line, which is one of the strongest indicators of long-term betting skill regardless of short-term results.
Learn more in Chapter 6: Variance & Standard Deviation and Chapter 4: Probability & Expected Value.
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