Confidence Interval Calculator
CI for a mean or proportion.
Confidence interval
48.0400 to 51.9600
Introduction
Build confidence intervals for population means or proportions from sample statistics. Choose confidence level and see lower and upper bounds. Use The Daily Tools' Confidence Interval Calculator for private, browser-based processing — no account or server upload required.
What is Confidence Interval Calculator?
Confidence Interval Calculator helps you ci for a mean or proportion. It belongs to the Sampling group within statistics tools on The Daily Tools. Enter your values and review the result with the assumptions shown on the page.
Definition: Confidence Interval Calculator is a free, browser-based calculator for cI for a mean or proportion.
Formula
CI = x̄ ± z × (σ ÷ √n) or p̂ ± z × √(p̂(1−p̂) ÷ n)
Calculation steps
- The core formula: CI = x̄ ± z × (σ ÷ √n) or p̂ ± z × √(p̂(1−p̂) ÷ n)
- Enter your values in the fields above — units and assumptions are under your control.
- The Daily Tools computes the result instantly in your browser using JavaScript.
- Review the result panel for the primary output and supporting breakdown values.
Worked example
Example: Using the Confidence Interval Calculator
Inputs: Enter values relevant to sampling — for example, the measurements or amounts described in the tool fields above.
- Open the Confidence Interval Calculator and review the input fields.
- Apply the formula: CI = x̄ ± z × (σ ÷ √n) or p̂ ± z × √(p̂(1−p̂) ÷ n)
- Adjust inputs to compare scenarios side by side.
You receive an immediate ci for a mean or proportion — useful for planning and comparison.
Use cases
- Working through a sampling question with clear inputs
- Comparing inputs in the Confidence Interval Calculator
- Using a focused tool instead of a general spreadsheet or manual calculation
Advantages
- Browser-based processing — entered values and selected files are not sent to our servers
- No account required
- Instant results with a clean, readable interface
- Transparent formula shown on this page
Limitations
- Results are estimates and do not replace professional advice
- Results are not saved by this tool after you leave or refresh the page
Frequently asked questions
- Is the Confidence Interval Calculator free to use?
- Yes. Confidence Interval Calculator on The Daily Tools is completely free, requires no account, and runs entirely in your browser.
- Does The Daily Tools store my inputs?
- No. Your numbers and text never leave your device. The Daily Tools has no backend database for calculator inputs.
- Who should use the Confidence Interval Calculator?
- Anyone who needs a clear statistics calculation and wants to check the assumptions used.
- How accurate is the Confidence Interval Calculator?
- Results follow the standard formula shown on this page. They are estimates for planning — not a substitute for professional advice.
- Can I use the Confidence Interval Calculator on mobile?
- Yes. The Daily Tools is fully responsive and works on phones, tablets, and desktops.
Sources & references
Key points
- Confidence Interval Calculator is a free, browser-based calculator for cI for a mean or proportion.
- Formula: CI = x̄ ± z × (σ ÷ √n) or p̂ ± z × √(p̂(1−p̂) ÷ n)
- Private, browser-only processing
- Private, browser-based processing