Pregnancy Due Date Calculator
HealthCalculate your pregnancy due date from your last menstrual period (LMP). Know your gestational age, trimester, and days remaining using Naegele's rule.
4th May 2026
Enter the first day of your last period
Average Cycle Length
days
20 days45 days
Estimated Due Date
—
Trimester
1st
Weeks Pregnant
—
Days Until Due
—
Select your LMP date above
What is a Pregnancy Due Date?
A Due Date Calculator estimates the date your baby is expected to be born — called the Estimated Due Date (EDD) or Expected Date of Delivery — based on the first day of your Last Menstrual Period (LMP). In India, the EDD is recorded on your Mother and Child Protection (MCP) card and drives the entire antenatal care schedule.
This calculator uses Naegele's rule, the universally accepted obstetric standard. It accounts for your individual cycle length: due date = LMP + 280 + (your cycle length − 28) days. For a standard 28-day cycle, this is simply LMP + 280 days (40 weeks).
Along with the due date, the calculator tells you:
- Weeks pregnant today — your current gestational age, which your doctor uses to track foetal development milestones
- Days until due date — practical countdown for preparing your hospital bag and maternity leave
- Current trimester — identifies which phase of pregnancy you are in and which antenatal tests are due
Note: The calculator outputs days until your due date. To find the actual due date, count that many days forward from today's date (e.g., 84 days from today = your calendar EDD). Your gynaecologist will confirm the EDD via first-trimester ultrasound.
Pair with the Ovulation Calculator for family planning and the Period Calculator for cycle tracking.
How to use this Pregnancy Due Date calculator
- Enter the first day of your last menstrual period (LMP) in the date field. If unsure, use the date your last period started.
- Enter your average cycle length using the slider. The default is 28 days. If your cycles are typically 30 or 32 days, adjust accordingly.
- The result shows days until your due date (highlight), weeks pregnant, days pregnant, and your current trimester.
- To find the actual due date: add the "Days Until Due Date" to today's date, or use the steps panel which displays the EDD in full.
- Use the trimester number to identify which routine antenatal tests are due for your stage of pregnancy.
- Share the EDD with your gynaecologist at your first visit; they will confirm it via ultrasound.
Formula & Methodology
Naegele's Rule (adjusted for cycle length):EDD = LMP + 280 + (cycle_length − 28) daysFor a standard 28-day cycle: EDD = LMP + 280 days = LMP + 40 weeks. Trimester boundaries (from LMP): - Trimester 1: Days 1–91 (Weeks 1–13) - Trimester 2: Days 92–182 (Weeks 14–26) - Trimester 3: Days 183–280 (Weeks 27–40) Worked example — LMP 1 January, cycle 30 days:Gestation period = 280 + (30 − 28) = 282 days EDD = 1 Jan + 282 days = 9 October If today is 1 April: Days pregnant = 90 days → Trimester 1 (end) Weeks pregnant = 12 weeks + 6 days Days until due = 191 daysKey pregnancy milestones by week: | Week | Milestone | |---|---| | 6–8 | Heartbeat visible on ultrasound | | 11–14 | NT scan + first-trimester blood screen | | 18–20 | Anomaly scan (level II ultrasound) | | 24–28 | Glucose tolerance test (GDM screening) | | 32–36 | Growth scan, GBS screening | | 37+ | Full term — baby ready for birth |
Frequently Asked Questions
How is the pregnancy due date calculated?
The due date is calculated using Naegele's rule: add 280 days (40 weeks) to the first day of your Last Menstrual Period (LMP). If your cycle is not 28 days, the calculator adjusts: due date = LMP + 280 + (your cycle length − 28) days. For example, a 30-day cycle gives LMP + 282 days. The result is the Estimated Due Date (EDD), also called Expected Date of Delivery (EDD) on Indian antenatal cards.
What is LMP and why is it used instead of conception date?
LMP stands for Last Menstrual Period — the first day of your most recent period before pregnancy. Conception typically occurs around day 14 of a 28-day cycle (ovulation), but the exact conception date is difficult to know precisely. The LMP date is easy to recall and marks a consistent, known reference point. Indian obstetricians universally use LMP for gestational age calculation on Mother and Child Protection (MCP) cards and antenatal records.
What does 'weeks pregnant' mean?
Gestational age in weeks is counted from the LMP date, not from the conception date. So when a doctor says 'you are 8 weeks pregnant', this means 8 weeks have passed since your LMP — which includes approximately 2 weeks before conception actually occurred. A full-term pregnancy is 40 weeks (280 days) from LMP. Babies born between 37 and 42 weeks are considered full-term; those before 37 weeks are preterm.
What is a trimester?
Pregnancy is divided into three trimesters, each approximately 13 weeks long. First trimester: weeks 1–13 (LMP day 1 to day 91) — major organ development, highest miscarriage risk. Second trimester: weeks 14–26 (days 92–182) — most comfortable phase, foetal movements begin. Third trimester: weeks 27–40 (days 183–280) — rapid growth, preparation for birth. Indian government antenatal care schedules have specific visits and tests mapped to each trimester.
How accurate is the due date?
The EDD is an estimate — only about 4% of babies are born on the exact due date. About 80% of births occur within 2 weeks before or after the EDD (between 38 and 42 weeks). Ultrasound dating in the first trimester (crown-rump length measurement) is more accurate than LMP-based calculation when LMP is uncertain or cycles are irregular. Your gynaecologist will use ultrasound to confirm or adjust the EDD during your first antenatal visit.
What if my cycle is not 28 days?
Ovulation typically occurs 14 days before the next period, not 14 days after LMP. So for a 30-day cycle, ovulation is around day 16, not day 14 — conception occurs 2 days later than in a standard 28-day cycle. The calculator accounts for this: due date = LMP + 280 + (cycle length − 28) days. Enter your actual average cycle length for a more accurate estimate. For very irregular cycles, ultrasound dating is more reliable.
What is the difference between EDD, EDB, and EDC?
All three mean the same thing. EDD = Estimated Due Date (most common in India and internationally). EDB = Estimated Date of Birth. EDC = Estimated Date of Confinement (older term, still seen on some Indian hospital records). Your MCP (Mother and Child Protection) card issued by government ANMs and hospitals will record the EDD, which is the date your antenatal care schedule is built around.
How do I use the Due Date Calculator?
Enter the first day of your Last Menstrual Period in the date field. If your average cycle length is not 28 days, adjust the cycle length slider accordingly. The calculator shows: days until your due date, how many weeks pregnant you are today, total days pregnant, and which trimester you are in. Note the number of days until your due date and add it to today's date to find the estimated delivery date.
When should I first see a gynaecologist in India?
The Ministry of Health and Family Welfare recommends the first antenatal visit within the first 12 weeks of pregnancy, ideally in the first trimester. Government health centres offer free antenatal care under the Janani Suraksha Yojana (JSY) and PMSMA (Pradhan Mantri Surakshit Matritva Abhiyan) schemes. Private hospitals in India typically schedule the first ultrasound between 6–8 weeks and a dating scan at 11–14 weeks (NT scan combined with blood tests).
What if I don't remember my LMP date?
If you don't know your LMP date, your obstetrician will use a first-trimester ultrasound (crown-rump length measurement) to estimate gestational age. This method is accurate to within ± 5–7 days in the first trimester and ± 2 weeks in the second trimester. For women with irregular cycles, PCOS, or those who were recently using hormonal contraception, ultrasound dating is the standard approach in Indian clinical practice.
What is a full-term pregnancy and what does premature mean?
A full-term pregnancy is 39–40 weeks from LMP. Early term is 37–38 weeks, full term is 39–40 weeks, late term is 41 weeks, and post-term is 42+ weeks. Preterm birth is before 37 weeks and carries higher risks of neonatal complications. In India, preterm birth rates are approximately 13% — one of the highest globally — making early antenatal care and accurate EDD calculation particularly important for monitoring and timely intervention.
Can I calculate the due date from conception date instead?
Yes: add 266 days (38 weeks) to your known or estimated conception date to get the EDD. If you know the date of intercourse that led to conception, the actual conception date is typically 0–5 days later (sperm can survive up to 5 days in the reproductive tract). However, exact conception dates are rarely known, which is why LMP-based calculation remains the clinical standard. Use this calculator with the LMP date as your input.