Confidence Interval for the Difference Between Means Calculator

A confidence interval for a difference between means is a range of values that is likely to contain the true difference between two population means with a certain level of confidence.

The formula to calculate the confidence interval is:

Confidence interval = (x₁–x₂) +/- t*√((s_p²/n₁) + (s_p²/n₂))

where:

• x₁, x₂: sample 1 mean, sample 2 mean
• t: the t-critical value based on the confidence level
• s_p²: pooled variance
• n₁, n₂: sample 1 size, sample 2 size

To find a confidence interval for a difference between two means, simply fill in the boxes below and then click the “Calculate” button.

x₁ (sample 1 mean)

s₁ (sample 1 standard deviation)

n₁ (sample 1 size)

x₂ (sample 2 mean)

s₂ (sample 2 standard deviation)

n₂ (sample 2 size)

Confidence level

95% C.I. = [-2.0049, 3.6049]

You can be 95% confident that the interval [-2.0049, 3.6049] contains the true difference between the population means μ₁ and μ₂.