Calculate your estimated due date and track your pregnancy journey. Find out how far along you are, which trimester you're in, and important milestones throughout your pregnancy.
Enter the first day of your last menstrual period. This is the most common method used to calculate due date.
If you know when you conceived or ovulated, enter that date for a more accurate calculation.
For IVF pregnancies, enter your embryo transfer date and the age of embryo at transfer.
Enter the date of your ultrasound and the gestational age determined by the scan.
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Only about 5% of babies are born on their exact due date. Most babies arrive within this window:
Our pregnancy due date calculator is designed so any expectant parent can get results in under a minute. Here’s exactly how each step works:
Select from four tabs: Last Menstrual Period (LMP), Conception Date, IVF Transfer, or Ultrasound. Each method is covered in detail in the section below.
Input the relevant date for your chosen method. For the LMP method, you can also adjust your average cycle length (21–45 days). The default is 28 days, but the calculator accommodates all normal cycle lengths.
Results appear instantly: your estimated due date, gestational age in weeks and days, trimester, days remaining, pregnancy progress percentage, and a full 12-milestone timeline with personalised dates.
Scroll through your baby’s current size and development, weekly tips, your delivery window (37–42 weeks), and the full pregnancy week calendar to plan ahead. If you want to track your weight during this journey, our BMI Calculator can help you monitor healthy weight ranges throughout each trimester.
Not sure which method to use? If you have a recent sonography report, the Ultrasound method gives the most precise result — particularly after week 12, when LMP-based estimates can drift by up to two weeks.
Our pregnancy calculator supports the same four methods used by OB-GYNs and midwives in clinical practice. Here’s when to use each one:
Most Common Method
Enter the first day of your last period plus your average cycle length. The tool applies Naegele’s Rule — adding 280 days (40 weeks) adjusted for your cycle — the global standard for due date estimation.
For Tracked Ovulation
Use this option if you tracked your ovulation with OPKs or basal body temperature. It gives a more accurate result than LMP for women with irregular or longer cycles.
For Assisted Conception
For IVF pregnancies, enter your transfer date and embryo age (Day 3, Day 5 blastocyst, or Day 6). Uses the precise fertilisation timing — the most accurate method for assisted conception.
Enter your scan date and the gestational age measured by your sonographer. First-trimester scans (8–13 weeks) are accurate within 5–7 days and will override LMP-based estimates if a significant discrepancy exists. Best for late starters, irregular LMP, or IVF confirmation. Accuracy: ±5–7 days.
ACOG (American College of Obstetricians and Gynecologists) recommends using first-trimester ultrasound to establish gestational age when the LMP is uncertain or when the crown-rump length (CRL) differs by more than 7 days from the LMP-based estimate. The IVF due date calculator uses the documented fertilisation date, giving it the highest precision of all four methods.
Reference: ACOG Committee Opinion — Methods for Estimating the Due Date
“How many weeks pregnant am I?” is one of the most searched pregnancy questions. Pregnancy is measured in gestational age, which is counted from the first day of your last menstrual period, not from the day of conception. Knowing your exact age in weeks is as important as knowing your chronological age — just as our Age Calculator helps you track time from any date, gestational age tracks your pregnancy from LMP to birth. This means when your doctor tells you that you are “4 weeks pregnant,” your embryo is biologically only about 2 weeks old. This 2-week offset is intentional — it is built into every standard pregnancy week calculator because ovulation and fertilisation typically occur around day 14 of a 28-day cycle.
Your pregnancy week calculator not only tells you how far along you are, but also what is happening developmentally at each stage:
If you conceived through in vitro fertilisation (IVF), the standard LMP method is significantly less reliable — because the timing of egg retrieval, fertilisation, and transfer is precisely controlled and documented. Our dedicated IVF due date calculator eliminates the guesswork by using the exact transfer date and embryo developmental stage:
IVF pregnancies have the same gestational milestones, trimester schedule, and prenatal care pathway as natural conceptions. The only difference is how the due date is initially calculated — everything from week 6 onwards follows the standard timeline. Your reproductive endocrinologist will confirm results with a 7-week viability scan and formal dating ultrasound before establishing your official EDD.
Weeks 1–12 — The Foundation
The first trimester is when rapid, foundational development takes place. By week 8, all major organs — heart, brain, lungs, and liver — have already begun forming. The heart starts beating around week 6, often visible on an early transvaginal scan.
Weeks 13–27 — The Golden Period
Most expectant parents find the second trimester the most comfortable stage. Nausea typically subsides by week 14, energy levels return, and the baby bump becomes clearly visible. First kicks (quickening) occur around weeks 18–22.
Weeks 28–40 — The Home Stretch
Characterised by rapid growth, organ maturation, and birth preparation. Lungs undergo critical surfactant production during weeks 32–36. Baby ideally rotates to head-down position by week 36.
Weeks 4–28 → every 4 weeks | Weeks 28–36 → every 2 weeks | Weeks 36–40 → every week. Do not miss the anatomy scan at week 20 or the Group B Streptococcus (GBS) swab at week 36.
Wondering exactly when you conceived? Our conception date calculator can work in both directions. If you enter your LMP and cycle length, the tool estimates your ovulation window and most likely conception date. For tracking the time elapsed since a specific date — like a transfer date or confirmed ovulation — our Time Duration Calculator is a quick companion tool. For a standard 28-day cycle, the fertile window falls around days 11–16. For a longer cycle of 35 days, ovulation shifts to approximately day 21, and the calculator adjusts automatically.
Every due date calculator — including those used by hospitals — provides an estimated due date (EDD), not a guaranteed delivery date. Only about 5% of babies are born on their exact EDD. Approximately 70% of full-term births occur within 10 days on either side of the calculated due date. Understanding percentages like these is easier with our Percentage Calculator — helpful when comparing risk figures from your screening results. Understanding this variability helps you prepare a realistic birth plan.
If your first-trimester ultrasound shows a crown-rump length that differs from your LMP-based estimate by more than 7 days, your OB-GYN or midwife will revise your due date to match the ultrasound measurement. This is standard ACOG protocol because ultrasound measurements are unaffected by cycle irregularities or uncertainty about your last period date.
ACOG Practice Bulletin No. 700 — Methods for Estimating the Due Date
Your pregnancy due date calculator result is the midpoint of a realistic 5-week delivery window, not a single target day. Here’s what each stage of that window means clinically:
Increased NICU risk; every additional week of gestation significantly improves outcomes. Elective delivery before 37 weeks is not recommended except for specific medical indications.
Lungs may still be maturing; elective induction before 39 weeks not generally recommended without medical indication.
Optimal time for birth; all organ systems fully matured; lowest risk of complications. This is your due date target zone.
Monitoring increases; induction may be discussed depending on cervical readiness and clinical assessment.
Induction strongly recommended; placental function begins to decline; meconium aspiration risk rises with each additional day.
Once you have confirmed your estimated due date, the next step is booking your first prenatal appointment. Here is a clinically recommended timeline to guide you from positive test to delivery:
Book as soon as you have a positive pregnancy test. Your provider will begin a care pathway and schedule your initial booking appointment, usually between weeks 8–10.
Initial blood work, urine tests, blood pressure baseline, family history review, and confirmation of your due date. Genetic testing options and lifestyle guidance are discussed at this visit.
The most accurate first-trimester dating scan. Combined with blood tests (PAPP-A, hCG) for chromosomal risk assessment. This scan also confirms or adjusts your due date if LMP and CRL measurements differ by more than 7 days.
Detailed check of all fetal organs, brain structure, spine, heart chambers, placenta position, and amniotic fluid volume. This is the single most important scan of your pregnancy — do not miss it.
Screens for gestational diabetes (GDM). If you have risk factors — BMI over 30(check yours with our BMI Calculator), previous GDM, family history of Type 2 diabetes, or South Asian ethnicity — earlier screening may be recommended.
Group B Streptococcus (GBS) swab at week 36, cervical readiness checks, fetal position assessment, and detailed discussions about birth preferences, pain relief options, and postpartum care planning.
Vaginal bleeding at any stage, severe abdominal pain, sudden severe headache with visual disturbances (signs of preeclampsia), decreased fetal movement after 28 weeks, signs of preterm labour before 37 weeks, or your waters breaking.
There are many online due date tools — but most offer only a single calculation method and a bare-bones result. Here’s what makes this pregnancy calculator different:
The LMP method applies Naegele’s Rule: take the first day of your last period, add 1 year, subtract 3 months, and add 7 days — which is equivalent to adding 280 days (40 weeks). If your cycle length differs from 28 days, the calculator adds the difference to the result. For example, a 35-day cycle adds 7 extra days to the due date. For IVF and known conception methods, it adds 266 days (38 weeks from fertilisation, which equals 40 gestational weeks).
In IVF, fertilizations happens in a laboratory on a precisely documented date. The IVF due date calculator uses the embryo transfer date and the age of the embryo at transfer (Day 3, 5, or 6) to work back to the exact fertilizations date, then adds 266 days to arrive at the EDD. This eliminates the cycle-length uncertainty inherent in the LMP method, giving IVF the highest accuracy of all four calculation methods.
Yes — if you enter your LMP and cycle length, our conception date calculator estimates your ovulation window and most likely conception date. Keep in mind that sperm can survive in the fallopian tubes for up to 5 days, so conception may have occurred several days before or on the day of ovulation. For the most precise result, enter your confirmed ovulation date from an OPK test rather than relying on cycle calculations alone.
The due date is a statistical midpoint, not a prediction. Biologically, normal full-term pregnancies range from 37 to 42 weeks, and labour onset depends on complex hormonal signals between mother and baby that science does not yet fully understand. Around 70% of births occur within 10 days of the EDD — so think of your pregnancy due date calculator result as the center of a window, not an exact deadline.
Folic acid (400–800 mcg daily) should be started before conception or as soon as you get a positive test, and continued through the first trimester to prevent neural tube defects. A complete prenatal supplement containing iron, calcium, vitamin D3, DHA (omega-3), iodine, and B12 is recommended throughout all 40 weeks. Do not start any new supplements without confirming the appropriate dosage with your OB-GYN, midwife, or GP.
Yes. The calculator supports cycle lengths from 21 to 45 days, making it accurate for users in any country — not only those with standard 28-day cycles. Prenatal care schedules and the types of recommended tests do vary by country. The milestone dates generated by this tool follow international obstetric guidelines (ACOG / RCOG standards), but you should always follow your local healthcare provider’s personalised care plan.
Due date calculations are estimates. Only about 5% of babies are born on their exact due date. Most babies arrive between 37-42 weeks. Ultrasound dating in the first trimester is typically most accurate (within 5-7 days).
If your cycle is longer than 28 days, ovulation likely occurred later, and your due date may be later. If shorter, you may have ovulated earlier. Our calculator adjusts for cycle length when using the LMP method.
Schedule your first prenatal appointment as soon as you have a positive pregnancy test, ideally around 8 weeks. If you have a history of pregnancy complications, see your doctor earlier.
Gestational age counts from the first day of your last menstrual period (LMP), which is about 2 weeks before conception. So when you’re “4 weeks pregnant,” your baby is actually about 2 weeks old since conception.
Yes, your healthcare provider may adjust your due date based on ultrasound measurements, especially if there’s more than a week’s difference between LMP and ultrasound dating. First-trimester ultrasounds are most accurate for dating.
This calculator provides estimates for informational purposes only and should not replace professional medical advice. Always consult with your healthcare provider for accurate pregnancy dating and personalized prenatal care.