How it works
Half-width is z times the standard error. Higher confidence widens the interval; larger n narrows it.
x̄ ± z·(σ/√n) · p̂ ± z√(p̂(1−p̂)/n)
When to use
Use this tool when you need to: calc.net demo: n=100, x̄=22.8, σ=2.7, 95% → about 22.8 ± 0.529. Or n=100, mean=50, sd=10 → [48.04, 51.96].
How to use this tool
- Enter your values in the fields above.
- Review the formula and any mode options for your problem.
- Read the result and the step-by-step solution.
Calc.net demo: n=100, x̄=22.8, σ=2.7, 95% → about 22.8 ± 0.529. Or n=100, mean=50, sd=10 → [48.04, 51.96].
Frequently asked questions
- What is the Confidence Interval Calculator?
- Half-width is z times the standard error. Higher confidence widens the interval; larger n narrows it.
- How do I use the Confidence Interval Calculator?
- Enter the required values, then calculate. The Confidence Interval Calculator shows results, formulas, and step-by-step work when available. No account is required.
- What formula does the Confidence Interval Calculator use?
- x̄ ± z·(σ/√n) · p̂ ± z√(p̂(1−p̂)/n)
- Average CalculatorArithmetic and weighted mean with a visual sum÷count layout and step-by-step work.
- Mean, Median, Mode, Range CalculatorArithmetic mean, median, mode(s), and range for comma-separated data — with ordered list, frequency table, and worked steps.
- Statistics CalculatorArithmetic and geometric means, σ and s, variance, quartiles, IQR, and Σx / Σx² from a comma-separated list.
- Standard Deviation CalculatorPopulation σ and sample s with variance, mean, sum, standard error, and margin of error for the mean.
- Number Sequence CalculatorArithmetic, geometric, and Fibonacci sequences: nth term, partial sum, and term list with clear formulas.
- Probability CalculatorIndependent two-event probabilities, solver, series of trials, normal range area, simple favorable/total, and Bayes.