Addition.site Due Date Calculator – Quick, Accurate, and Free
Welcome to the Due Date Calculator on Addition.site – your one‑stop, web‑based tool for estimating the due date of a pregnancy. Whether you’re an expectant parent, a healthcare provider, or simply curious about how due dates are calculated, this calculator gives you a free, instant, reliable result in just a few clicks.
How It Works
-
Enter Your Last Menstrual Period (LMP)
• Click the calendar icon next to “last menstrual period” and pick the first day of your most recent period.
• The date must be entered in the standard YYYY‑MM‑DD format (the browser’s date picker handles this automatically). -
Click “Calculate”
• The calculator adds 280 days (40 weeks) to the LMP – the medically accepted average length of a human pregnancy.
• The result appears in the read‑only “Result” field in YYYY‑MM‑DD format. -
Copy or Share
• Click the result field to copy the due date to your clipboard.
• Click the “𝕏” button to share the calculated date directly on X (formerly Twitter).
Why 280 Days?
- Gestational Age: The typical human pregnancy lasts about 40 weeks from the first day of the last menstrual period.
- Standard Calculation: Adding 280 days to the LMP yields the estimated due date, which is widely used by obstetricians, midwives, and expectant parents worldwide.
- Variability: Actual delivery may occur a few days before or after the calculated date; this tool provides a best‑guess estimate.
Use Cases
| Scenario | How the Calculator Helps |
|---|---|
| Expectant Parents | Quickly estimate when to start prenatal care, plan for maternity leave, or arrange childcare. |
| Healthcare Professionals | Verify due dates during routine check‑ups or when preparing for a delivery. |
| Family Planning | Estimate due dates when planning for multiple pregnancies or adjusting birth spacing. |
| Educators & Students | Demonstrate the basic math behind gestational age calculations in biology or health classes. |
Features & Accessibility
- Responsive Design: Works on desktops, tablets, and smartphones.
- Clipboard Support: One click copies the due date for easy sharing or note‑taking.
- Share on X: Immediate social media integration for quick updates.
- Emoji Toggle: Lighten the experience with a fun emoji switch.
- No Sign‑Up Required: Purely client‑side JavaScript; no data is stored or sent.
Technical Notes
- The calculator is built with vanilla JavaScript (
due-date-calc.js) and uses theDateobject to perform the calculation. - It adds 280 days (
dueDate.setDate(lmp.getDate() + 280)) to the user’s input. - The result is displayed in ISO date format (
yyyy-mm-dd), ensuring consistency across all devices.
SEO Highlights
- Primary Keywords: Due date calculator, pregnancy due date, estimate due date, last menstrual period calculator
- Meta Description: “Calculate your pregnancy due date quickly and accurately. Enter your last menstrual period and get an instant result. Share on X!”
- Open Graph: Optimized for sharing on social platforms with a clear title, description, and image.
Ready to find out when your little one might arrive?
Enter your last menstrual period, click “Calculate,” and let Addition.site’s Due Date Calculator do the math for you. Enjoy a free, quick, reliable estimate and share the excitement with friends and family!