---
title: "Confidence Interval Calculator"
method: GET
path: "/api/calc/confidence-interval-calculator"
tags: ["Math"]
---

# Confidence Interval Calculator

`GET /api/calc/confidence-interval-calculator`

## Request

- Base URL: `https://calcbright.com`
- URL: `https://calcbright.com/api/calc/confidence-interval-calculator`
- Auth: none declared

Confidence intervals for a mean (t or z) or a proportion (Wald and Wilson) at 80–99.9% confidence – margin of error, critical value and every step shown.

## Query parameters

- `type` 'mean-t' | 'mean-z' | 'prop': Interval for
- `conf` '80' | '85' | '90' | '95' | '98' | '99' | '99.9': Confidence level
- `mean` number: Sample mean (x̄)
- `sd` number: Sample SD (s)
- `x` number: Successes (x)
- `n` number: Sample size (n)

## Response `200`

Calculation result

- CalcOutput
  - `ok` boolean
  - `tool` string
  - `name` string
  - `url` string: Open this link to see the full calculation
  - `inputs` object
  - `summary` string: Plain-text answer
  - `details` string
  - `result` object
  - `errors` object

## Other responses

- `400`: Invalid input (see errors)

---

[API](https://skmtc.dev/calcbright/apis/calcbright-calculator-api.md) · [All operations](https://skmtc.dev/calcbright/apis/calcbright-calculator-api/llms.txt) · [OpenAPI document](https://skmtc.dev/calcbright/apis/calcbright-calculator-api/revisions/f58229e56e58?raw)