- Trusted Pregnancy Tool · Updated 2026
All-in-One Pregnancy Calculator & Due Date Tracker
Estimate your due date, current pregnancy week, and trimester instantly. Supports LMP, conception, IVF, ultrasound, and reverse calculations, with weekly baby development insights.
- Medically-based formulas
- Instant results
- Free PDF report
Last Menstrual Period (LMP)
Uses the first day of your last period to estimate your due date (LMP + 280 days).
Conception Date
If you know the approximate date of conception, we'll add 266 days to estimate your due date.
IVF Pregnancy Calculator
Accurate when you know the embryo transfer date and embryo age at transfer.
Ultrasound Due Date
Use measurements from your scan — most accurate dating method in the first trimester (weeks 8–13).
Reverse Due Date Calculator
Already know your due date? We'll estimate your conception date and approximate LMP.
Pregnancy Trimesters
Pregnancy is divided into three trimesters, each marking a distinct phase of your baby’s growth and your body’s transformation.
Weeks 1–12
The foundation phase
- Baby's heart begins beating around week 6
- All major organs start to form
- Morning sickness is common weeks 6–9
- First prenatal visit recommended
- Nuchal translucency scan at week 11–13
Weeks 13–26
The golden phase
- Energy returns, nausea often subsides
- Baby starts to move, you'll feel kicks
- Anatomy scan (20 weeks) checks development
- Gender can often be determined
- Baby develops hearing and responds to sound
Weeks 27–40
The final stretch
- Baby gains most of its weight now
- Lungs mature in preparation for birth
- Weekly prenatal visits begin at week 36
- Baby moves into head-down position
- Full term reached at 39 weeks
Important Pregnancy Milestones
These are the landmark moments most expectant mothers and their doctors watch closely throughout pregnancy.
Week 6
Heartbeat Detected
Baby’s heart begins beating, often visible on an early ultrasound scan at around 6–7 weeks.
Week 11–13
Nuchal Scan
First-trimester screening checks for chromosomal conditions and confirms gestational age.
Week 20
Anatomy Scan
Detailed ultrasound checks all major organs and structures. Gender is often revealed at this scan.
Week 16–22
First Kicks Felt
Quickening, the first fluttering sensations of baby movement, is typically felt between weeks 16 and 22.
Week 24
Viability Milestone
At 24 weeks, baby has a significant chance of survival outside the womb with appropriate medical care.
Week 39–40
Full Term
Your baby is considered full term at 39 weeks. Most healthy pregnancies deliver between weeks 38 and 42.
Week-by-Week Pregnancy Insights
Explore what’s happening with your baby and your body every week of pregnancy.
Frequently Asked Questions
Answers to the most common questions about pregnancy due date calculation and tracking.
How accurate is a pregnancy due date calculator?
A pregnancy due date calculator is usually accurate within a few days when based on a reliable last menstrual period (LMP) date. However, only about 5% of babies are born exactly on their due date, most arrive within two weeks before or after. An early ultrasound (8–13 weeks) is considered the most accurate dating method and can refine your estimated due date.
How is a pregnancy due date calculated?
The most common method — Naegele’s rule — adds 280 days (40 weeks) to the first day of your last menstrual period. This assumes a 28-day cycle with ovulation on day 14. Adjustments are made if your cycle is longer or shorter. Alternative methods include adding 266 days to a known conception date, or using IVF transfer dates and ultrasound measurements.
Can an ultrasound change my due date?
Yes. A first-trimester ultrasound (between 8 and 13 weeks) is the gold standard for pregnancy dating. If the baby’s measurements differ from your LMP-based estimate by more than 5–7 days, your doctor will typically revise your due date to match the ultrasound findings. Later ultrasounds are less accurate for dating.
How does IVF due date calculation work?
Yes. A first-trimester ultrasound (between 8 and 13 weeks) is the gold standard for pregnancy dating. If the baby’s measurements differ from your LMP-based estimate by more than 5–7 days, your doctor will typically revise your due date to match the ultrasound findings. Later ultrasounds are less accurate for dating.
What week does pregnancy officially start?
Pregnancy is officially counted from the first day of your last menstrual period (LMP), even though conception doesn’t occur until about two weeks later. This means by the time you get a positive pregnancy test (around week 4), your pregnancy is already considered to be 4 weeks along. The full pregnancy lasts approximately 40 weeks from LMP.
Can cycle length affect my due date estimate?
Absolutely. The standard Naegele’s rule assumes a 28-day cycle. If your cycles are longer (e.g. 35 days), you ovulate later, meaning your actual conception date is later — and your due date should be adjusted forward. This calculator accounts for cycle length variation so your estimate is more personalized and accurate.
- Stay Updated
Get Weekly Fitness Tips, Diet Plans & Tool Updates
Medical Disclaimer
This pregnancy calculator provides estimated dates for informational purposes only and does not replace professional medical advice, diagnosis, or treatment. Due dates are estimates, only about 5% of babies are born on their exact due date. Always consult your obstetrician, midwife, or healthcare provider for personalized guidance throughout your pregnancy.
Ready to Track Your Pregnancy Journey?
Use our all-in-one calculator to stay informed every step of the way, from your due date to each week’s development milestones.