Pregnancy Due Date Calculator
Calculate your accurate pregnancy due date using last menstrual period, conception date, or ultrasound dating. Get personalized pregnancy milestones and week-by-week tracking.
📅 Last Menstrual Period
💕 LMP Results
💕 Conception Details
💕 Conception Results
🔬 Ultrasound Dating
💕 Ultrasound Results
📚 HOW TO USE THE PREGNANCY DUE DATE CALCULATOR
Last Menstrual Period (LMP) Calculator
Enter the first day of your last menstrual period and select your average cycle length using our interactive slider (21-35 days) or preset buttons. The calculator uses Naegele's Rule, adding 280 days to your LMP date while adjusting for cycle length variations. Choose your cycle regularity and maternal age for personalized accuracy assessment and risk category determination.
LMP Calculation Guidelines:
- Regular Cycles (28 days): Most accurate LMP-based dating
- Short Cycles (21-26 days): Earlier ovulation adjustment
- Long Cycles (29-35 days): Later ovulation compensation
- Irregular Cycles: Lower accuracy, ultrasound recommended
Conception Date Calculator
Input your known conception date for the most precise due date calculation. Add 266 days (38 weeks) from conception for your estimated delivery date. Select your conception method, ovulation tracking approach, and confidence level to receive accuracy ratings. This method works best for women who tracked ovulation or underwent fertility treatments.
Conception Tracking Methods:
- Basal Body Temperature: Temperature spike confirmation
- Ovulation Predictor Kits: LH surge detection
- Cervical Mucus Changes: Fertile mucus observation
- Ultrasound Monitoring: Medical ovulation confirmation
Ultrasound Dating Calculator
Enter your ultrasound date and gestational age shown on your scan report. Include additional days if specified (e.g., 8 weeks 3 days) and select ultrasound type for accuracy assessment. The calculator converts ultrasound measurements to LMP-equivalent dating and provides revised due date with precision indicators based on scan timing.
Ultrasound Accuracy by Timing:
- 6-13 weeks: ±5 days accuracy (most precise)
- 14-20 weeks: ±7-10 days accuracy
- 21-28 weeks: ±10-14 days accuracy
- After 28 weeks: ±21-30 days accuracy
FREQUENTLY ASKED QUESTIONS❓
How accurate is a pregnancy due date calculator?
Pregnancy due date calculators provide estimates within 1-3 weeks accuracy depending on the method used. LMP-based calculations are accurate for women with regular 28-day cycles, while conception date calculations offer higher precision (±3-5 days). Only about 5% of babies arrive exactly on their due date, with most births occurring between 38-42 weeks gestation. First trimester ultrasounds provide the most accurate dating method.
What's the difference between LMP and conception date calculations?
LMP calculations add 280 days from your last menstrual period, assuming ovulation occurred on day 14 of a 28-day cycle. Conception date calculations add 266 days from actual fertilization, providing more precision for women who tracked ovulation or know exact conception timing. LMP dating is standard medical practice, while conception dating offers personalized accuracy for irregular cycles.
Can I use the calculator with irregular menstrual cycles?
Yes, but irregular cycles reduce accuracy of LMP-based calculations. Women with cycles shorter or longer than 28 days should adjust expectations accordingly. The calculator accounts for cycle length variations (21-35 days) and provides accuracy assessments. For irregular cycles, conception date or early ultrasound dating typically offers better precision than LMP calculations.
When should I get an ultrasound to confirm my due date?
Schedule a dating ultrasound between 6-12 weeks gestation for optimal accuracy. Early ultrasounds measure crown-rump length (CRL) to determine gestational age within ±5 days. If there's more than 5-7 days difference between LMP and ultrasound dating, your healthcare provider may adjust your due date based on ultrasound measurements, especially for irregular cycles.
How does maternal age affect pregnancy due date calculations?
Maternal age doesn't directly impact due date calculations but influences pregnancy risk assessment and monitoring schedules. Women over 35 receive "advanced maternal age" classification requiring additional monitoring, while those over 40 need specialized high-risk care. Age affects pregnancy management and delivery planning but not the fundamental 280-day gestation period calculation.
What happens if my due date gets changed during pregnancy?
Due date revisions are common, especially after first trimester ultrasounds. Medical providers may adjust dates if there's significant discrepancy between LMP and ultrasound measurements. Early pregnancy (before 20 weeks) revisions are most reliable, while later adjustments account for individual fetal growth variations rather than dating accuracy.
How do I calculate my pregnancy weeks and trimester dates?
Pregnancy weeks count from your LMP date, with gestational age being 2 weeks ahead of embryonic age. First trimester ends at 13 weeks (91 days), second trimester spans 14-27 weeks, and third trimester covers 28-42 weeks. Each week starts on the same weekday as your LMP, making tracking straightforward with consistent reference points.
Can fertility treatments affect due date calculations?
Fertility treatments like IVF, IUI, and ovulation induction provide precise conception timing, making due date calculations highly accurate. IVF transfers use embryo age plus transfer date for exact calculations. IUI procedures use insemination date plus 266 days. Fertility patients often have the most accurate due dates due to controlled timing and frequent monitoring.
💡 PREGNANCY MILESTONE TRACKING
First Trimester Milestones:
- Weeks 4-6: Missed period and early pregnancy symptoms
- Weeks 6-8: First prenatal appointment and confirmation
- Weeks 8-10: First ultrasound and heartbeat detection
- Weeks 11-13: First trimester screening and nuchal translucency
Second Trimester Highlights:
- Weeks 14-16: Gender determination possibility
- Weeks 18-22: Anatomy scan and detailed evaluation
- Weeks 20-24: Fetal movement and viability milestone
- Weeks 24-28: Glucose screening and third trimester preparation
Third Trimester Preparations:
- Weeks 28-32: Regular monitoring and growth assessments
- Weeks 32-36: Birth plan preparation and final preparations
- Weeks 36-40: Weekly appointments and labor readiness
- Weeks 40-42: Post-term monitoring and delivery decisions
Important Pregnancy Dates:
- Viability Date: 24 weeks (survival threshold)
- Pre-term Birth: Before 37 weeks gestation
- Full Term: 37-42 weeks optimal delivery window
- Post-term: After 42 weeks requiring intervention
Perfect for expectant mothers seeking accurate pregnancy dating and comprehensive milestone tracking! 💕👶
⚠️ Disclaimer: This pregnancy calculator is for informational purposes only and should not replace professional medical advice. Results are estimates based on general guidelines. Consult qualified healthcare providers for personalized recommendations. Individual pregnancies may vary based on health, cycle patterns, and personal circumstances.