---
title: "Ovulation Calculator"
method: POST
path: "/api/v1/tools/ovulation-calculator"
tags: ["tools"]
---

# Ovulation Calculator

`POST /api/v1/tools/ovulation-calculator`

## Request

- Base URL: `https://toolforte.com`
- URL: `https://toolforte.com/api/v1/tools/ovulation-calculator`
- Auth: HTTP bearer

Fertile window and ovulation day from the last period and cycle length. The calendar method places ovulation 14 days before the next period rather than 14 days after the last one, opens the fertile window five days before it and closes it one day after, and projects the same pattern across three cycles. Estimate only, consult your midwife or doctor.

## Request body

- object
  - `lastPeriod` string
  - `cycleLength` integer
  - `today` string

## Response `200`

Successful result

- object
  - `ok` boolean
  - `data` object
    - `cycleLength` integer
    - `cycles` object[]
      - `periodStart` string
      - `ovulation` string
      - `fertileStart` string
      - `fertileEnd` string
      - `nextPeriod` string
    - `ovulation` string
    - `fertileWindow` object
      - `start` string
      - `end` string
    - `nextPeriod` string
    - `daysUntilOvulation` integer
    - `daysUntilNextPeriod` integer
    - `note` string

## Other responses

- `400`: Missing or invalid request fields
- `401`: Invalid or missing API key
- `429`: Monthly plan limit reached

---

[API](https://skmtc.dev/toolforte/apis/toolforte-api.md) · [All operations](https://skmtc.dev/toolforte/apis/toolforte-api/llms.txt) · [OpenAPI document](https://skmtc.dev/toolforte/apis/toolforte-api/revisions/4d814d484dfc?raw)