Free Pregnancy Due Date Calculator – Estimate Your Baby's Due Date
Use this free pregnancy due date calculator to estimate your baby's arrival. Choose from five calculation methods — last menstrual period, conception date, intercourse date, IVF transfer, or ultrasound. You'll get your estimated due date (EDD), current pregnancy week, trimester, baby's approximate size, and a birth probability calendar. No sign‑up required — all calculations happen right in your browser.
How to Calculate Your Pregnancy Due Date Online for Free
This free online pregnancy due date calculator helps you estimate when your baby will arrive. It uses the same standard obstetric formulas that doctors and midwives use — Naegele's Rule for period‑based calculations, and straightforward day‑counting for conception, IVF, and ultrasound methods. Just pick your method, enter a date, and click calculate. You'll see your estimated due date, how many weeks pregnant you are, which trimester you're in, your baby's approximate size, and a birth probability calendar showing the most likely delivery window.
How Your Due Date Is Calculated – The Science Behind Each Method
- Last Menstrual Period (LMP) — Naegele's Rule. This is the standard method used by OB/GYNs worldwide. We add 280 days (40 weeks) to the first day of your last period, then adjust for your cycle length. If your cycle is longer than 28 days, ovulation likely occurs later, so your due date moves forward. If shorter, ovulation occurs earlier, and your due date shifts back. This pregnancy due date calculator from last period gives you a personalized estimate based on your unique cycle.
- Conception Date. A full‑term pregnancy lasts about 266 days (38 weeks) from conception. If you know the exact date you conceived — for example, from ovulation tracking — we add 266 days to find your due date. This conception date calculator method is especially useful for those who use ovulation predictor kits or fertility monitors.
- Intercourse Date. Sperm can live in the female reproductive tract for up to 5 days, so the date of intercourse isn't always the date of conception. We add approximately 2 days to the intercourse date to estimate conception, then add 266 days. This intercourse date pregnancy calculator provides a reasonable estimate when you know the most likely conception window.
- IVF Transfer. This is the most precise method. For a Day 3 embryo transfer, we add 263 days to the transfer date. For a Day 5 blastocyst transfer, we add 261 days. This IVF due date calculator reflects the exact embryo age at transfer, giving you a highly accurate due date.
- Ultrasound. An early first‑trimester ultrasound is the clinical gold standard for pregnancy dating. We use the gestational age measured by the scan (in weeks and days) and the date of the ultrasound to calculate your due date. If your doctor has given you a due date based on a scan, that is the most reliable date to use.
Why Use This Pregnancy Due Date Calculator?
- No registration. A true free pregnancy due date calculator no sign up required. Start calculating immediately — no accounts, no email, no spam.
- Five calculation methods. Choose from LMP, conception, intercourse, IVF transfer, or ultrasound. This pregnancy calculator covers every common scenario, including IVF pregnancy due date and ultrasound due date calculator options.
- Cycle length adjustment. Unlike many calculators that assume a 28‑day cycle, this pregnancy due date calculator with cycle length lets you enter your actual average cycle for a more personalized estimate.
- Complete pregnancy tracking. See your current pregnancy week, trimester, baby's approximate size and weight, estimated conception date, and days remaining until your due date — all in one view.
- Birth probability calendar. Visualize your due date window with a calendar that highlights the two weeks before and after your EDD — the period when most babies are born.
- Key milestone dates. See when you'll reach important pregnancy milestones — first heartbeat detection, end of first trimester, anatomy scan, viability, full term, and more.
- 100% private. All calculations happen in your browser. No personal health data is ever uploaded or stored.
- Works on any device. Phone, tablet, or computer — just a modern browser.
Pregnancy Timeline: Key Milestones
| Milestone | Timing | What Happens |
|---|---|---|
| First Heartbeat | Weeks 6–9 | Baby's heartbeat can be detected via transvaginal ultrasound — one of the first exciting milestones. |
| End of First Trimester | Week 12 | Risk of miscarriage drops significantly. Many parents feel comfortable sharing their news at this point. |
| Anatomy Scan & Gender | Weeks 18–22 | Mid‑pregnancy ultrasound checks baby's development. Parents can often find out the baby's sex if they choose. |
| Viability | Week 24 | A baby born at this stage has a chance of survival with intensive medical care. Every week after this increases that chance significantly. |
| End of Second Trimester | Week 28 | Third trimester begins. Baby focuses on gaining weight and preparing for birth. Prenatal check‑ups become more frequent. |
| Full Term | Week 37 | Baby is considered full term. Lungs are mature and ready for life outside the womb. Labor can begin any time now. |
| Due Date | Week 40 | Only about 4–5% of babies are born on their exact due date. Most arrive within two weeks before or after. |
Pregnancy Terms at a Glance
| Term | Weeks | What It Means |
|---|---|---|
| Preterm | Less than 37 weeks | May need extra medical support. |
| Early Term | 37 weeks – 38 weeks, 6 days | Healthy, but final development is still underway. |
| Full Term | 39 weeks – 40 weeks, 6 days | Optimal window for delivery. |
| Late Term | 41 weeks – 41 weeks, 6 days | Monitoring or induction may be discussed. |
| Post-term | 42 weeks and beyond | Labor might be induced to reduce risks. |
Step‑by‑Step: How to Use the Pregnancy Due Date Calculator
- Choose your calculation method. Click one of the five tabs — Last Period, Conception, Intercourse, IVF Transfer, or Ultrasound. LMP is the most common method and is selected by default.
- Enter your details. Fill in the required fields. For LMP, enter the first day of your last period and your average cycle length. For IVF, select whether it was a Day 3 or Day 5 embryo transfer. For ultrasound, enter the gestational age from your scan report.
- Click "Calculate My Due Date". Your estimated due date appears instantly, along with your pregnancy week, trimester, baby's size and weight, conception date, days remaining, birth probability calendar, and key milestone dates.
Frequently Asked Questions
Q: Is this pregnancy due date calculator really free?
A: Yes, 100% free. No sign‑up, no hidden costs, and no personal data collection. This is a truly free pregnancy due date calculator — use it as many times as you need, no strings attached.
Q: How accurate is this due date calculator?
A: Only about 4–5% of babies are born on their exact due date. Your EDD is the center of your "due date window" — it's completely normal to give birth in the two weeks before or after. This pregnancy calculator uses standard obstetric formulas (Naegele's Rule) and adjusts for cycle length, giving you results comparable to clinical tools. An early first‑trimester ultrasound is the most accurate dating method.
Q: Can I use this calculator if my cycles are irregular?
A: Yes, but the estimate will be less precise. You can enter your best estimate of your average cycle length. For very irregular cycles, doctors often rely on an early ultrasound to set or confirm the due date. This pregnancy due date calculator for irregular periods provides the best estimate possible with the information you have.
Q: How does cycle length affect my due date?
A: The standard 280‑day calculation assumes you ovulate on day 14 of a 28‑day cycle. If your cycle is longer (e.g., 35 days), you likely ovulate later, which pushes your due date forward. If your cycle is shorter (e.g., 21 days), ovulation occurs earlier, and your due date moves back. This pregnancy due date calculator with cycle adjustment handles this automatically.
Q: What is a "full‑term" pregnancy?
A: A full‑term pregnancy is 39 weeks, 0 days to 40 weeks, 6 days. Early term is 37–38 weeks, late term is 41 weeks, and post‑term is 42 weeks and beyond. The full‑term window is considered the optimal time for delivery.
Q: Is my data stored or shared when I use this calculator?
A: Never. All calculations run locally in your browser. No personal health information — including your last period date, conception date, or IVF transfer date — is ever uploaded, stored, or shared with any server or third party. Your privacy is guaranteed.
Learn how to use this tool correctly by reading our step-by-step tutorial.
