AIAZHHow To Use
- Enter the first day of your last menstrual period.
- Enter your average cycle length in days (default is 28).
- Click "Calculate Due Date" to see your estimated due date.
- Review the conception date estimate and current pregnancy week.
- Share the due date with your healthcare provider for confirmation.
Frequently Asked Questions
How is the 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. The cycle length adjustment accounts for ovulation timing in longer or shorter cycles.
How accurate is the due date?
Only about 5% of babies are born on their exact due date. Most arrive within two weeks before or after. The due date is an estimate — your healthcare provider may adjust it based on early ultrasound measurements.
What is the difference between LMP and conception date?
LMP (last menstrual period) is the first day of your last period. Conception typically occurs about 14 days after LMP (around ovulation). The calculator estimates both dates for reference.
How are trimesters divided?
Pregnancy is divided into three trimesters. First trimester: weeks 1-12. Second trimester: weeks 13-27. Third trimester: weeks 28-40. Each trimester marks different stages of fetal development.
Is my pregnancy data stored or shared?
No. All calculations are performed locally in your browser. Your personal data never leaves your device.
When should I see a healthcare provider?
Schedule your first prenatal appointment as soon as you suspect pregnancy. Early prenatal care is important for maternal and fetal health. Bring your estimated due date from this calculator to discuss with your provider.
Naegele's Rule
Uses Naegele's rule, the standard medical method for estimating due dates: add 280 days (40 weeks) from the first day of your last menstrual period.
Week-by-Week Tracking
See your current pregnancy week, trimester, and weeks remaining. Track your progress throughout your pregnancy journey.
100% Private & Secure
Your pregnancy data never leaves your device. All calculations happen locally in your browser with JavaScript.
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No account required, no email needed. Use the due date calculator unlimited times for free.
Calculate Your Pregnancy Due Date Instantly
Our free pregnancy due date calculator uses Naegele's rule to estimate your baby's arrival date. Simply enter your last menstrual period date and cycle length to get your estimated due date, conception date, and current pregnancy week.
Understanding Your Pregnancy Timeline
A full-term pregnancy is 40 weeks (280 days) from the first day of your last menstrual period. The due date marks the end of week 40. Babies born between 37 and 42 weeks are considered full-term. Your healthcare provider will monitor your progress throughout.
First Trimester: What to Expect (Weeks 1-12)
The first trimester is a critical period of development. Major organs and systems form during these weeks. Common symptoms include fatigue, morning sickness, breast tenderness, and frequent urination. Schedule your first prenatal visit early in this trimester.
Preparing for Your Due Date
As your due date approaches, prepare by packing a hospital bag, finalizing your birth plan, installing the car seat, and preparing a nursery. Attend regular prenatal checkups and discuss any concerns with your healthcare provider.