Confidence interval calculator

Calculate confidence interval calculator with clear inputs and assumptions.

Your inputs stay in your browser. Displayed results are rounded to a maximum of 12 significant digits.

Method and assumptions

Method version 1.0.0 · Updated October 17, 2026

Calculate

Formula: Calculate confidence interval calculator with clear inputs and assumptions.

Calculate confidence interval calculator with clear inputs and assumptions.

mean: Mean
sd: Standard deviation (> 0)
count: Sample size (> 0)

Results are estimates where noted and depend on the entered assumptions.

Calculate with code

These short examples use the same inputs and core calculation as this tool. Adapt validation and formatting to your application.

JavaScript

const mean = 50, sd = 10, n = 100, z = 1.96;
const margin = z * sd / Math.sqrt(n);
console.log([mean-margin, mean+margin]); // 95% normal interval: [48.04, 51.96]

TypeScript

const mean=50, sd=10, n=100, z=1.96;
const margin: number = z*sd/Math.sqrt(n);
console.log([mean-margin, mean+margin]);

Python

import math
mean, sd, n, z = 50, 10, 100, 1.96
margin = z*sd/math.sqrt(n)
print(mean-margin, mean+margin)  # 95% normal interval

Java

double margin=1.96*10/Math.sqrt(100);
System.out.println((50-margin) + " to " + (50+margin)); // 95% interval

double margin=1.96*10/Math.Sqrt(100);
Console.WriteLine($"{50-margin} to {50+margin}"); // 95% interval