Weeks To Months Pregnancy Calculator
The Weeks-to-Months Pregnancy Calculator is a simple and accurate tool to help expectant mothers and healthcare providers track pregnancy progress. By entering the number of weeks and days, this calculator provides months pregnant, trimester, fetal development stage, and estimated percentage complete.
How to Use the Pregnancy Calculator
- Enter Weeks Pregnant
Input the total number of weeks since conception. - Enter Additional Days
Include any extra days beyond full weeks to improve accuracy. - Optional: Last Menstrual Period (LMP)
Enter your LMP date to cross-check estimated due dates. - Optional: Estimated Due Date
Input the due date to see weeks and days remaining. - Click Calculate
The calculator displays:- Total Pregnancy Duration: weeks and days
- Months Pregnant: approximate months
- Trimester: First, Second, Third, or Overdue
- Percentage Complete: progress toward 40 weeks
- Weeks and Days Remaining: until 40 weeks
- Development Stage: what is happening with the baby
Example: 20 Weeks Pregnant
- Total Duration: 20 weeks, 0 days
- Months Pregnant: 4 months
- Trimester: Second Trimester (14–26 weeks)
- Percentage Complete: 50%
- Weeks Remaining: 20 weeks
- Days Remaining: 140 days
- Development Stage: Gender Determination Possible
This shows that at 20 weeks, the pregnancy is halfway complete and the baby’s gender can often be determined via ultrasound.
Pregnancy Trimesters
| Trimester | Weeks | Key Milestones |
|---|---|---|
| First Trimester | 1–13 | Early development, organ formation |
| Second Trimester | 14–26 | Rapid growth, movement begins, gender determination |
| Third Trimester | 27–40 | Brain development, weight gain, full-term preparation |
| Overdue | 40+ | Monitor closely for delivery |
Fetal Development Stages by Weeks
- Weeks 0–4: Embryonic Period – Early Development
- Weeks 4–8: Embryonic Period – Organ Formation
- Weeks 8–12: Fetal Period – Rapid Growth
- Weeks 12–16: Movement Begins
- Weeks 16–20: Gender Determination Possible
- Weeks 20–24: Viability Threshold
- Weeks 24–28: Brain Development
- Weeks 28–32: Weight Gain Phase
- Weeks 32–37: Pre-Term Phase
- Weeks 37–40: Full Term – Ready for Birth
- Weeks 40+: Post-Term – Monitor Closely
Why Use This Calculator
- Track Pregnancy Progress: Know how far along you are in weeks, months, and trimesters.
- Monitor Fetal Development: Understand what stage your baby is in.
- Estimate Completion: See percentage completed and time remaining until full term.
- Educational Resource: Helpful for first-time parents and students in health fields.
- Supports Planning: Plan prenatal care, ultrasounds, and important milestones.
Tips for Accurate Results
- Always enter weeks and days accurately.
- Optional dates (LMP and Due Date) improve precision.
- Check with a healthcare provider for medical decisions; this tool is informational only.
- Track your progress over time for a better understanding of fetal growth.
This Weeks-to-Months Pregnancy Calculator is a handy tool for tracking your pregnancy, understanding your trimester, and staying informed about fetal development.