Pregnancy Month Calculator
Enter your last menstrual period (LMP) to estimate your current pregnancy month, gestational age, due date, and trimester.
How this pregnancy month calculator works
A pregnancy month calculator estimates how far along a pregnancy is based on gestational age, which starts on the first day of your last menstrual period (not the conception date). This is the same method most clinics use.
After you enter your LMP date, the calculator determines your total weeks and days pregnant, maps that to a pregnancy month range, and estimates your due date using a standard 280-day pregnancy length.
Pregnancy month by week chart
| Pregnancy Month | Week Range | Trimester |
|---|---|---|
| Month 1 | Weeks 1–4 | First trimester |
| Month 2 | Weeks 5–8 | First trimester |
| Month 3 | Weeks 9–13 | First trimester |
| Month 4 | Weeks 14–17 | Second trimester |
| Month 5 | Weeks 18–22 | Second trimester |
| Month 6 | Weeks 23–27 | Second trimester |
| Month 7 | Weeks 28–31 | Third trimester |
| Month 8 | Weeks 32–35 | Third trimester |
| Month 9 | Weeks 36–40 | Third trimester |
Why weeks and months can look confusing
Many people ask, “How many months pregnant am I?” because everyday life is usually discussed in months. However, pregnancy development is medically tracked by weeks because fetal milestones happen quickly and week-by-week tracking is more precise.
- Doctors use weeks: for appointments, scans, and growth milestones.
- Parents often use months: for easy communication with family and friends.
- Both are valid: as long as you understand the week-to-month conversion can vary slightly.
What the calculator estimates
When you click calculate, you get:
- Current gestational age in weeks and days
- Current pregnancy month
- Current trimester
- Estimated due date (EDD)
- Estimated conception date
- Approximate percent of pregnancy completed
Tips for more accurate results
1) Use an accurate LMP date
This calculator is most accurate when your menstrual cycles are regular and you know the exact first day of your last period.
2) Enter your average cycle length
If your cycle is consistently longer or shorter than 28 days, use the cycle length field. The due date estimate adjusts accordingly.
3) Confirm with ultrasound and your provider
Home tools are for planning and education. A clinician can provide the most reliable dating through ultrasound and clinical evaluation.
Frequently asked questions
Is pregnancy really 9 months or 10 months?
Pregnancy is usually measured as 40 weeks from LMP. That’s around 9 calendar months, but it can feel like 10 “lunar months” (4-week blocks).
Can my due date change?
Yes. Early ultrasound can refine dating, especially if your cycle is irregular or if ovulation happened earlier or later than expected.
What if I am past 40 weeks?
Some pregnancies continue beyond 40 weeks. Your provider may monitor you more closely and discuss options for safe delivery timing.