Pregnancy Week Calculator
Calculate exactly how many weeks pregnant you are with precise date ranges
Enter your last menstrual period date or conception date to calculate exactly how many weeks pregnant you are.
Get a complete week-by-week breakdown of your pregnancy with precise dates and milestones.
Calculate important pregnancy information:
- • Current pregnancy week and days
- • Trimester information
- • Week equivalence table
- • Precise date ranges for each week
How to Calculate Pregnancy Weeks
Our pregnancy week calculator uses the standard medical method to determine how many weeks pregnant you are. Healthcare providers calculate pregnancy weeks from the first day of your last menstrual period (LMP), not from the conception date. This method provides the most accurate and consistent pregnancy dating.
A full-term pregnancy is considered 40 weeks from your LMP date. This calculator provides you with precise date ranges for each week of pregnancy, helping you track your progress throughout your journey.
Why Use a Pregnancy Week Calculator?
Accurate Pregnancy Dating
Get precise calculations based on medical standards used by healthcare providers worldwide. Our calculator ensures consistency with your doctor's pregnancy dating.
Track Your Progress
See exactly which week you're in and how many days you've progressed. Perfect for monitoring your pregnancy milestones and appointments.
Detailed Week Breakdown
View all 40 weeks of pregnancy with specific date ranges, making it easy to plan appointments and understand your pregnancy timeline.
Multiple Input Options
Calculate from your last menstrual period or conception date. Choose the method that's most accurate for your situation.
Understanding Pregnancy Weeks vs Months
Pregnancy is measured in weeks rather than months because weeks provide more precision. While people often ask "how many months pregnant am I?", healthcare providers use weeks because they offer more accurate tracking of fetal development and due date calculations.
Quick Reference:
- • First trimester: Weeks 1-12
- • Second trimester: Weeks 13-26
- • Third trimester: Weeks 27-40
- • Full-term pregnancy: 37-40 weeks
Frequently Asked Questions
How accurate is this pregnancy week calculator?
Our calculator uses the same method as healthcare providers - counting from your last menstrual period. It's very accurate for standard 28-day cycles, but individual variations may occur. Always confirm with your healthcare provider.
What does LMP mean?
LMP stands for "Last Menstrual Period" - specifically the first day of your last menstrual cycle before you became pregnant. This date is used as the standard starting point for calculating pregnancy weeks because it's easier to remember than the exact conception date. Your LMP date is what doctors use to determine your due date and track your pregnancy progress.
What if I don't remember my last menstrual period?
If you know your conception date, you can use that option in our calculator. The calculator will automatically adjust the calculation. If you're unsure of both dates, consult your healthcare provider who can date your pregnancy using ultrasound.
Why do pregnancy weeks start before conception?
Medical pregnancy dating includes the two weeks before conception as part of the pregnancy calculation. This standardizes pregnancy dating since ovulation and conception dates can vary, but the menstrual cycle provides a more consistent starting point.