Stats Calculator Online
Confidence Intervals Calculators
Estimate population parameters with confidence intervals. Free tools on Stats Calculator Online with formulas, how-to steps, similar calculator widgets, tidbits, and exportable reports.
- CI for a Mean CalculatorConfidence interval for a population mean
- CI for a Proportion CalculatorConfidence interval for a proportion
- CI for SD CalculatorConfidence interval for a standard deviation
- CI for Difference in Means CalculatorInterval for mu1 - mu2
- CI for Difference in Proportions CalculatorInterval for p1 - p2
- CI for Correlation CalculatorFisher z interval for Pearson r
- Margin of Error CalculatorCompute margin of error for means or proportions
Tidbits from Stats Calculator Online
Resources
Critical value tables nearby
Jump to z, t, χ², and F tables when you need critical values alongside an online calculator.
Open tables →Best practice
Check assumptions before you trust p
Independence, normality (or large n), and equal variances matter for classic t/ANOVA. Use Welch or rank tests when they fail.
Two-sample t-test →Plan ahead
Power before you collect data
Fix the smallest meaningful effect and α, then compute sample size. Inflate n for dropout when recruiting humans.
Sample size calculator →
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