Pregnancy Due Date Calculator – Find Your Baby’s Due Date Instantly

Calculate your pregnancy due date, track weekly progress, and discover key milestones with FlickTool’s free Pregnancy Due Date Calculator. Enter your last period date, conception date, IVF transfer date, or a known due date — and instantly get your due date, current week, trimester, days until birth, baby size comparison, and a complete pregnancy milestone timeline.

How Pregnancy Due Date Calculation Works

A standard pregnancy lasts approximately 40 weeks (280 days) from the first day of the last menstrual period (LMP). This is the basis of Naegele’s Rule — the most widely used due date calculation method in obstetrics — which adds 280 days to the LMP date to estimate the expected delivery date (EDD).

However, not every pregnancy starts from a known LMP. Women with irregular cycles, those who conceived through IVF, or those who know their conception date need different calculation methods. FlickTool’s calculator supports all four approaches, ensuring accurate results regardless of how you are tracking your pregnancy. Always confirm your due date with your healthcare provider, as ultrasound dating often provides the most accurate gestational age assessment.

How to Use the Pregnancy Due Date Calculator

Getting your results takes under a minute:

1. Select your calculation method from the dropdown — Due Date, Last Period, Conception Date, or IVF Transfer Date
2. Enter the relevant date using the calendar date picker for your chosen method
3. For Last Period: select your average cycle length (22, 28, 30, 35, or 45 days) for adjusted accuracy
4. For IVF Transfer: select your embryo age — Day 3, Day 5, or Day 6 transfer
5. Click “Calculate” to generate your full pregnancy profile
6. Review your results — due date, weeks pregnant, current trimester, and days until birth
7. Check the Pregnancy Progress circle showing your percentage completion
8. View the Trimester Timeline bar with your current week marked across all three trimesters
9. See your baby’s current size compared to a familiar object
10. Explore the Milestone Timeline for key development checkpoints throughout your pregnancy
11. Read a fun fact about your baby’s current stage of development
12. Save or Share your journey using the action buttons

Click Reset to clear all fields and start a new calculation.

Four Calculation Methods Explained

Last Period Date

The most commonly used method. Enter the first day of your last menstrual period and select your average cycle length. The calculator adjusts the due date based on your cycle since ovulation — and therefore conception — occurs later in longer cycles.

Conception Date

If you know when conception occurred through ovulation tracking, basal body temperature charting, or ovulation predictor kits, enter that date directly. The calculator adds 266 days (38 weeks) from conception to estimate your due date.

IVF Transfer Date

For IVF pregnancies, gestational age is calculated from the egg retrieval date adjusted for embryo age. Select your transfer date and embryo age — Day 3, Day 5, or Day 6 — and the calculator determines your equivalent LMP date to produce an accurate due date.

Known Due Date

If your doctor or midwife has already given you a due date from an ultrasound, enter it directly. The calculator works backwards to show your current week, trimester, days remaining, milestone timeline, and all other pregnancy tracking information.

Key Features Explained

Pregnancy Progress Circle

A visual progress circle shows what percentage of your 40-week pregnancy is complete. Watching this number grow week by week is a meaningful way to track your journey toward your due date.

Trimester Timeline

A colour-coded timeline bar spans all 40 weeks divided into three trimesters, with your current week marked precisely. See at a glance where you are in the first trimester (weeks 1-12), second trimester (weeks 13-27), or third trimester (weeks 28-40).

Baby Size Comparison

Each week of pregnancy is associated with a familiar size comparison — from a poppy seed in week 4 to a watermelon near term. This beloved pregnancy tracking tradition makes abstract developmental measurements tangible and relatable.

Milestone Timeline

Key development milestones appear on a visual timeline showing when your baby’s heartbeat begins, when major organs form, when movement starts, and when your baby reaches full lung maturity. These milestones give context and meaning to each passing week.

For tracking your health and wellness habits throughout pregnancy alongside this calculator, FlickTool’s Daily Habit Tracker helps you monitor hydration, prenatal vitamins, sleep, and exercise consistently.

Frequently Asked Questions

1. How accurate is the due date calculation?

Ans. The calculator uses standard obstetric formulas including Naegele’s Rule for LMP-based calculation and adjusted formulas for conception and IVF dates. Only about 5% of babies are born on their exact due date — the result is an estimated due date within a two-week window. Always confirm with your midwife or obstetrician via ultrasound for the most accurate gestational dating.

2. What cycle length should I select if my periods are irregular?

Ans. Select the cycle length closest to your average. If your cycle varies significantly, a conception date or ultrasound-based due date will be more accurate than an LMP-based calculation. Speak with your healthcare provider about tracking ovulation for more precise dating.

3. How is IVF due date calculation different?

Ans. IVF due dates are calculated from the egg retrieval date adjusted by the embryo’s age at transfer. A Day 5 transfer means the embryo is already 5 days old, so the equivalent LMP date is calculated accordingly. This method is generally more precise than LMP-based calculation since the conception moment is known exactly.

4. What are the three trimesters?

Ans. The first trimester covers weeks 1 through 12 and includes the most critical early development. The second trimester spans weeks 13 through 27, typically the most comfortable phase with visible growth and movement. The third trimester runs from week 28 to birth, focused on weight gain and final organ maturation.

5. Is my pregnancy data stored or shared?

Ans. No. All calculations run locally in your browser. No dates, personal details, or pregnancy information are transmitted to any server or stored anywhere outside your own device.