Due Date Calculator API

Overview

To use Due Date Calculator, you need an API key. You can get one by creating a free account and visiting your dashboard.

GET Endpoint

https://api.apiverve.com/v1/duedatecalculator

Example

How to call the Due Date Calculator API in different programming languages.

curl -X GET \
  "https://api.apiverve.com/v1/duedatecalculator?last_period=2025-06-01" \
  -H "X-API-Key: your_api_key_here"

const response = await fetch('https://api.apiverve.com/v1/duedatecalculator?last_period=2025-06-01', {
  method: 'GET',
  headers: {
    'X-API-Key': 'your_api_key_here',
    'Content-Type': 'application/json'
  }
});

const data = await response.json();
console.log(data);

import requests

headers = {
    'X-API-Key': 'your_api_key_here',
    'Content-Type': 'application/json'
}

response = requests.get('https://api.apiverve.com/v1/duedatecalculator?last_period=2025-06-01', headers=headers)

data = response.json()
print(data)

package main

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

)

func main() {
    req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/duedatecalculator?last_period=2025-06-01", nil)

    req.Header.Set("X-API-Key", "your_api_key_here")
    req.Header.Set("Content-Type", "application/json")

    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()

    body, _ := io.ReadAll(resp.Body)
    fmt.Println(string(body))
}

{
  "status": "ok",
  "error": null,
  "data": {
    "calculation_method": "last_period",
    "last_period_date": "2024-01-01",
    "estimated_conception_date": "2024-01-15",
    "due_date": "2024-10-07",
    "current_progress": {
      "days_pregnant": 715,
      "weeks_pregnant": 102,
      "days_into_week": 1,
      "formatted": "102 weeks, 1 days",
      "trimester": 3,
      "percentage_complete": 255.36
    },
    "time_until_due": {
      "days": 0,
      "weeks": 0,
      "days_extra": 0,
      "formatted": "Past due date",
      "is_overdue": true
    },
    "upcoming_milestones": [],
    "important_dates": {
      "end_first_trimester": "2024-04-01",
      "end_second_trimester": "2024-07-08",
      "full_term_begins": "2024-09-16"
    },
    "disclaimer": "This is an estimate only. Due dates can vary. Consult your healthcare provider for medical advice."
  }
}

Authentication

The Due Date Calculator API requires authentication via API key. Include your API key in the request header:

X-API-Key: your_api_key_here

Learn more about authentication →

Interactive API Playground

Test the Due Date Calculator API directly in your browser with live requests and responses.

Parameters

The Due Date Calculator API supports multiple query options. Use one of the following:

Response

The Due Date Calculator API returns responses in JSON, XML, YAML, and CSV formats. The JSON response is shown in the Example section above; alternative formats below.

Other Response Formats

<?xml version="1.0" encoding="UTF-8"?>
<response>
  <status>ok</status>
  <error xsi:nil="true" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
  <data>
    <calculation_method>last_period</calculation_method>
    <last_period_date>2024-01-01</last_period_date>
    <estimated_conception_date>2024-01-15</estimated_conception_date>
    <due_date>2024-10-07</due_date>
    <current_progress>
      <days_pregnant>715</days_pregnant>
      <weeks_pregnant>102</weeks_pregnant>
      <days_into_week>1</days_into_week>
      <formatted>102 weeks, 1 days</formatted>
      <trimester>3</trimester>
      <percentage_complete>255.36</percentage_complete>
    </current_progress>
    <time_until_due>
      <days>0</days>
      <weeks>0</weeks>
      <days_extra>0</days_extra>
      <formatted>Past due date</formatted>
      <is_overdue>true</is_overdue>
    </time_until_due>
    <upcoming_milestones>
    </upcoming_milestones>
    <important_dates>
      <end_first_trimester>2024-04-01</end_first_trimester>
      <end_second_trimester>2024-07-08</end_second_trimester>
      <full_term_begins>2024-09-16</full_term_begins>
    </important_dates>
    <disclaimer>This is an estimate only. Due dates can vary. Consult your healthcare provider for medical advice.</disclaimer>
  </data>
</response>

status: ok
error: null
data:
  calculation_method: last_period
  last_period_date: '2024-01-01'
  estimated_conception_date: '2024-01-15'
  due_date: '2024-10-07'
  current_progress:
    days_pregnant: 715
    weeks_pregnant: 102
    days_into_week: 1
    formatted: 102 weeks, 1 days
    trimester: 3
    percentage_complete: 255.36
  time_until_due:
    days: 0
    weeks: 0
    days_extra: 0
    formatted: Past due date
    is_overdue: true
  upcoming_milestones: []
  important_dates:
    end_first_trimester: '2024-04-01'
    end_second_trimester: '2024-07-08'
    full_term_begins: '2024-09-16'
  disclaimer: >-
    This is an estimate only. Due dates can vary. Consult your healthcare
    provider for medical advice.

Response Structure

All API responses follow a consistent structure with the following fields:

Learn more about response formats →

Response Data Fields

When the request is successful, the data object contains the following fields:

Headers

Only X-API-Key is required. Optional headers include Accept for response format negotiation (JSON, XML, or YAML), User-Agent, and X-Request-ID for request tracing. See all request headers →

GraphQL AccessALPHA

Access Due Date Calculator through GraphQL to combine it with other API calls in a single request. Query only the due date calculator data you need with precise field selection, and orchestrate complex data fetching workflows.

Credit Cost: Each API called in your GraphQL query consumes its standard credit cost.

POST https://api.apiverve.com/v1/graphql

query {
  duedatecalculator(
    input: {
      last_period: "2025-06-01"
    }
  ) {
    calculation_method
    last_period_date
    estimated_conception_date
    due_date
    current_progress {
      days_pregnant
      weeks_pregnant
      days_into_week
      formatted
      trimester
      percentage_complete
    }
    time_until_due {
      days
      weeks
      days_extra
      formatted
      is_overdue
    }
    upcoming_milestones
    important_dates {
      end_first_trimester
      end_second_trimester
      full_term_begins
    }
    disclaimer
  }
}

Note: Authentication is handled via the x-api-key header in your GraphQL request, not as a query parameter.

CORS Support

The Due Date Calculator API accepts cross-origin requests from any origin, so it can be called directly from browser-based applications without a proxy. See CORS support →

Rate Limiting

Due Date Calculator requests are throttled per minute on the Free plan and unthrottled on paid plans. Exceeding the limit returns 429 Too Many Requests; rate-limit usage is reported in the X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset response headers. See per-plan limits and best practices →

Error Codes

The Due Date Calculator API uses standard HTTP status codes — 200 on success, 400 for invalid parameters, 401 for missing or invalid keys, 403 for insufficient credits, 429 for rate-limit exhaustion, and 500/503 for server-side issues. Each error response includes an X-Request-ID header you can quote when contacting support. See full error handling guide →

SDKs for Due Date Calculator

Official Due Date Calculator packages on npm, PyPI, NuGet, and JitPack — plus a Postman collection and an OpenAPI spec. See the SDK guide →

JitPack

No-Code Integrations

Due Date Calculator works with Zapier, Make, Pipedream, n8n, and Power Automate using the same API key. See setup guides →

Zapier

Make

Pipedream

n8n

Power Automate

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