Pregnancy Due Date Calculator
Calculate your baby's due date and pregnancy calendar
Last Menstrual Period (LMP)
Important: Enter the first day of your last menstrual period (LMP). The due date is calculated by adding 280 days (40 weeks) to this date. Results are estimates - only about 5% of babies are born on their exact due date.
No Calculation Yet
Enter your last period date and click Calculate
Pregnancy by Trimester
First Trimester
Weeks 1-13
- • Confirmation of pregnancy
- • First ultrasound scan
- • NT scan (11-13 weeks)
- • Morning sickness common
- • Major organs developing
Second Trimester
Weeks 14-27
- • Anatomy scan (18-20 weeks)
- • Gender determination possible
- • Feel baby movements
- • Glucose screening (24-28 weeks)
- • Energy levels improve
Third Trimester
Weeks 28-40
- • Weekly checkups from week 36
- • Group B Strep test (35-37 weeks)
- • Baby gains weight rapidly
- • Prepare for delivery
- • Watch for labor signs
When to Use Pregnancy Calculator
Planning & Preparation
Know your due date to plan maternity leave, prepare nursery, schedule baby shower, and arrange work coverage ahead of time.
Medical Appointments
Schedule prenatal checkups, ultrasounds, and important tests at the right weeks for optimal maternal and fetal health monitoring.
Tracking Development
Follow your baby's growth week by week, understand developmental milestones, and know what to expect at each stage of pregnancy.
First-Time Parents
New parents can use the calculator to understand pregnancy timeline, prepare emotionally and financially, and know what to expect.
Family Planning
Couples trying to conceive can track potential due dates, plan optimal conception times, and understand fertility windows better.
Birth Planning
Plan birth preferences, hospital tours, birth class schedules, and discuss delivery options with healthcare providers at appropriate times.
Frequently Asked Questions
How is pregnancy due date calculated?
Pregnancy due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). This is based on Naegele's rule, which assumes a 28-day menstrual cycle with ovulation occurring on day 14. The calculation: Due Date = LMP + 280 days. For example, if your last period started on January 1, your due date would be October 8.
How accurate is the due date calculator?
Due date calculators are reasonably accurate estimates, but only about 5% of babies are born on their exact due date. Most babies (about 70%) are born within 10 days before or after the calculated due date. Factors affecting accuracy include irregular menstrual cycles, uncertain LMP dates, and individual variations in pregnancy length. Early ultrasound measurements (before 12 weeks) can provide more accurate dating.
Is this pregnancy calculator free?
Yes, our pregnancy due date calculator is completely free to use with no limitations. Calculate your due date, view your pregnancy calendar, and access prenatal checkup schedules without any registration, subscription, or hidden costs. All calculations are performed instantly in your browser with complete privacy.
What if I don't remember my last period date?
If you don't remember your last menstrual period date, your healthcare provider can estimate your due date through: 1) Early ultrasound examination (most accurate if done before 12 weeks), 2) Physical examination measuring uterus size, 3) First fetal movement (quickening) typically felt around 18-20 weeks. Early prenatal care is important for accurate dating and monitoring.
When should I have prenatal checkups?
Standard prenatal checkup schedule: Weeks 1-28: Every 4 weeks, Weeks 28-36: Every 2-3 weeks, Weeks 36-40: Every week. Important checkups include: First visit (6-8 weeks) for confirmation, 11-13 weeks for NT scan, 15-20 weeks for anatomy scan, 24-28 weeks for glucose screening, 35-37 weeks for Group B Strep test. Your doctor may recommend more frequent visits if you have risk factors.
What happens at each prenatal visit?
Typical prenatal visits include: weight and blood pressure monitoring, urine testing for protein and glucose, measuring fundal height (uterus size), listening to fetal heartbeat, discussing symptoms and concerns. Specific tests occur at certain weeks: blood tests, ultrasounds, genetic screening, glucose tolerance test, and Group B Strep screening. Each visit ensures both mother and baby are healthy.
Can my due date change?
Yes, your due date may be adjusted based on early ultrasound measurements, especially if done before 12 weeks gestation. If the ultrasound shows the baby is significantly smaller or larger than expected based on your LMP, your provider may revise your due date. However, due dates are rarely changed after 20 weeks unless there was clear error in the original calculation.
What if I go past my due date?
Going past your due date is common - about 30% of pregnancies continue beyond 40 weeks. Most doctors will monitor you more frequently with non-stress tests and ultrasounds. If you reach 41-42 weeks without labor, your provider will likely recommend induction to reduce risks. Post-term pregnancies (beyond 42 weeks) have increased risks, so medical intervention is usually recommended.
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