Ovulation Calculator

Overview

Includes current cycle status, days until ovulation, and educational information about cycle phases, perfect for fertility tracking and family planning applications.

Endpoint

One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.

curl "https://api.apiverve.com/v1/ovulationcalculator?last_period=2024-01-01&cycle_length=28" \
  -H "x-api-key: your_api_key_here"

const res = await fetch('https://api.apiverve.com/v1/ovulationcalculator?last_period=2024-01-01&cycle_length=28', {
  headers: { 'x-api-key': 'your_api_key_here' },
});

if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);

const { data } = await res.json();
console.log(data);

import requests

res = requests.get(
    "https://api.apiverve.com/v1/ovulationcalculator?last_period=2024-01-01&cycle_length=28",
    headers={"x-api-key": "your_api_key_here"},
    timeout=15,
)
res.raise_for_status()

print(res.json()["data"])

package main

import (
	"fmt"
	"io"
	"net/http"
)

func main() {
	req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/ovulationcalculator?last_period=2024-01-01&cycle_length=28", nil)
	req.Header.Set("x-api-key", "your_api_key_here")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()

	out, _ := io.ReadAll(res.Body)
	fmt.Println(string(out))
}

Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.

Authentication

Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.

Parameters

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them.

Response

Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.

{
  "status": "ok",
  "error": null,
  "data": {
    "last_period": "2024-01-01",
    "cycle_length": 28,
    "ovulation": {
      "date": "2024-01-15",
      "days_from_last_period": 14
    },
    "fertile_window": {
      "start": "2024-01-10",
      "end": "2024-01-15",
      "duration_days": 6
    },
    "most_fertile_days": {
      "start": "2024-01-13",
      "end": "2024-01-15",
      "duration_days": 3
    },
    "fertile_days": [
      {
        "date": "2024-01-10",
        "day_relative_to_ovulation": -5,
        "fertility_level": "medium",
        "description": "Fertile"
      },
      {
        "date": "2024-01-11",
        "day_relative_to_ovulation": -4,
        "fertility_level": "medium",
        "description": "Fertile"
      },
      {
        "date": "2024-01-12",
        "day_relative_to_ovulation": -3,
        "fertility_level": "medium",
        "description": "Fertile"
      },
      {
        "date": "2024-01-13",
        "day_relative_to_ovulation": -2,
        "fertility_level": "high",
        "description": "Most fertile"
      },
      {
        "date": "2024-01-14",
        "day_relative_to_ovulation": -1,
        "fertility_level": "high",
        "description": "Most fertile"
      },
      {
        "date": "2024-01-15",
        "day_relative_to_ovulation": 0,
        "fertility_level": "high",
        "description": "Most fertile"
      }
    ],
    "next_period": {
      "date": "2024-01-29",
      "days_from_last_period": 28
    },
    "cycle_phases": {
      "follicular_phase": {
        "duration_days": 14,
        "description": "From first day of period to ovulation"
      },
      "ovulation": {
        "duration_days": 1,
        "description": "Egg is released from ovary"
      },
      "luteal_phase": {
        "duration_days": 14,
        "description": "From ovulation to next period"
      }
    },
    "current_status": {
      "current_phase": "Menstruation",
      "is_fertile": false,
      "days_until_ovulation": -701,
      "days_until_next_period": -687
    },
    "disclaimer": "This calculator provides estimates only. Actual ovulation may vary. Consult a healthcare provider for medical advice."
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.

Use cases

Fertility Tracking

Build fertility tracking applications with accurate ovulation predictions based on cycle length and last period date

Conception Planning

Calculate conception probability windows and most fertile days to help users plan or prevent pregnancy

Menstrual Health

Create menstrual health apps with ovulation tracking, fertile window identification, and cycle insights

Family Planning

Provide family planning tools with science-based ovulation calculations and fertility awareness features

Other ways to use Ovulation Calculator

Set up Ovulation Calculator on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.

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