---
title: "Period Calculator"
method: GET
path: "/api/calc/period-calculator"
tags: ["Health"]
---

# Period Calculator

`GET /api/calc/period-calculator`

## Request

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

Predict your next six periods from the date your last one started and your cycle length, with ovulation days and fertile windows on the same calendar.

## Query parameters

- `date` string, date: First day of your last period (YYYY-MM-DD)
- `cycle` number: Average cycle length (days) From the first day of one period to the first day of the next – 28 on average.
- `length` number: Period length (days)

## 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)