Adjusted R-squared calculator
Enter ordinary R², the observation count and the number of predictors excluding the intercept.
How do I use this page?
- Enter model R².
- Enter n and predictor count.
- Compare R² with adjusted R².
What this page does not do: The formula assumes a model with an intercept. It does not test regression assumptions or prediction quality.
Further reading
Theory — what is adjusted R-squared?
Adjusted R-squared is a variant of the coefficient of determination that accounts for the number of predictors and the sample size. Ordinary R² never decreases when another variable is added to a model, even if it contributes little useful information, which makes comparing models with different numbers of predictors unfair. The calculator derives the adjusted value from ordinary R², the number of observations n, and the number of predictors p excluding the intercept, making it better suited to comparing nested models for the same outcome Y.
Frequently asked questions
Does the intercept count as a predictor?
Why is adjusted R² lower?
See also
A/B test calculator
Compare two proportions in an A/B test. Calculate conversion rates, difference, uplift, z score, p value and c
A/B test planning — sample size, MDE and duration
Plan a two-proportion experiment, estimate detectable effect and traffic duration.
ACF and PACF autocorrelation calculator
Calculate ACF and PACF across time-series lags. Review the chart, reference bounds and coefficient table.