Statistics

Confidence Interval Calculator

Calculate statistical confidence intervals for data analysis

Interval Type*

Confidence Level*

Sample Mean

Standard Deviation (σ or s)

Sample Size*

Sample Proportion (p̂)

Lower Bound

48.0400

Upper Bound

51.9600

Margin of Error (±)

1.9600

Mean CI: x̄ ± z × (σ / √n)
Proportion CI: p̂ ± z × √(p̂(1−p̂)/n)

Common z-scores:
  90% → 1.645 | 95% → 1.960 | 99% → 2.576

Supported inputs

Input	Description
Interval Type	mean · proportion
Confidence Level	The confidence level for the interval 80% · 85% · 90% · 95% · [object Object] · 99.9%
Sample Mean	Enter the arithmetic mean of your sample
Standard Deviation (σ or s)
Sample Size	Enter the total count of observations
Sample Proportion (p̂)	For proportion CI: observed proportion (0–1)

Formula

Mean CI: x̄ ± z × (σ / √n)
Proportion CI: p̂ ± z × √(p̂(1−p̂)/n)

Common z-scores:
  90% → 1.645 | 95% → 1.960 | 99% → 2.576

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