🤰Pregnancy Week Calculator
Track your pregnancy journey week by week. Calculate your current pregnancy week, due date, ovulation and conception timeline, and get personalized information about your baby's development.
Pregnancy Information
Date Information:
First day of your last menstrual period
Your Pregnancy
Pregnancy Trimesters
1st Trimester (Weeks 1-12)
• Major organ development
• Morning sickness may occur
• Fatigue and breast tenderness
• First prenatal appointments
2nd Trimester (Weeks 13-27)
• Energy levels often improve
• Baby movements felt
• Anatomy scan performed
• Gender can be determined
3rd Trimester (Weeks 28-40)
• Rapid baby growth
• Increased discomfort
• Prepare for delivery
• Regular checkups increase
Frequently Asked Questions
📅 How accurate are pregnancy calculators?
Pregnancy calculators are estimates with 95% accuracy when using LMP method. Only about 5% of babies are born exactly on their due date.
🤰 Which calculation method is most accurate?
If you know the exact conception date, that”s most accurate. Otherwise, LMP method is standard. Ultrasound dating in first trimester is most precise.
👶 When can I feel baby movements?
First-time mothers typically feel movements between 16-20 weeks. Experienced mothers may feel them as early as 13-16 weeks.
🏥 When should I start prenatal care?
Schedule your first prenatal visit as soon as you know you”re pregnant, ideally by 8 weeks of pregnancy.
How to Use This Calculator
This pregnancy week calculator helps you determine exactly how far along you are in your pregnancy. Follow these steps:
- Select your calculation method. You can calculate based on your Last Menstrual Period (LMP), a known conception date, or your estimated due date provided by your healthcare provider.
- Enter the relevant date. For the LMP method, enter the first day of your last period and your average cycle length. For the conception method, enter the exact date conception occurred. For the due date method, enter the date your doctor has given you.
- View your results. The calculator will show your current pregnancy week and day, your trimester, your estimated due date, days remaining, baby development information for your current week, weekly tips, upcoming milestones, and scheduled prenatal appointments.
Understanding Pregnancy Weeks
Pregnancy is measured in gestational weeks, which are counted from the first day of the last menstrual period (LMP) rather than from the date of conception. This means that during the first two weeks of "pregnancy," conception has not yet occurred. The system is used because the LMP date is typically more reliably remembered than the exact date of conception.
A full-term pregnancy lasts 40 weeks (280 days) from the LMP or 38 weeks (266 days) from conception. Pregnancy is expressed in the format "X weeks, Y days" -- for example, "16 weeks 3 days" means the pregnancy has completed 16 full weeks and is 3 days into the 17th week.
First Trimester Highlights (Weeks 1-12)
The first trimester is a period of rapid cellular development. By week 4, the embryo has implanted in the uterine wall and the neural tube (which becomes the brain and spinal cord) begins forming. By week 6, the heart starts beating. By the end of week 12, all major organ systems have formed, and the risk of miscarriage drops significantly. Common symptoms include nausea, fatigue, breast tenderness, and frequent urination.
Second Trimester Highlights (Weeks 13-27)
Often considered the most comfortable period of pregnancy, the second trimester brings increased energy and reduced nausea for most women. The baby grows quickly -- by week 16, movements may be felt (known as "quickening"), and by week 20 the anatomy scan ultrasound can reveal detailed information about the baby's structure. At week 24, the baby reaches the viability milestone, meaning survival outside the womb becomes possible with intensive medical care.
Third Trimester Highlights (Weeks 28-40)
The third trimester is marked by rapid growth and maturation. The baby gains significant weight, the lungs mature, and the brain develops rapidly. Mothers may experience Braxton Hicks contractions, increased discomfort, shortness of breath, and difficulty sleeping. Regular prenatal visits increase in frequency during this period. By week 37, the baby is considered early full-term, and by week 39-40, the baby is fully prepared for life outside the womb.
Understanding Ovulation & Your Fertile Window
Ovulation is the process by which a mature egg is released from one of the ovaries and travels down the fallopian tube, where it can be fertilized by sperm. It typically occurs about 14 days before the start of your next menstrual period, regardless of your overall cycle length. For a 28-day cycle, ovulation usually falls around day 14; for a 30-day cycle, around day 16.
Your fertile window spans approximately six days: the five days before ovulation and the day of ovulation itself. This window exists because sperm can survive in the female reproductive tract for up to five days, while the released egg remains viable for only 12 to 24 hours. The two to three days immediately before ovulation are the days with the highest conception probability.
Signs of Ovulation
Physical Signs
- - Clear, stretchy cervical mucus (egg-white consistency)
- - Slight rise in basal body temperature (0.2-0.5 F)
- - Mild pelvic or lower abdominal pain (mittelschmerz)
- - Increased sex drive
- - Breast tenderness
Tracking Methods
- - Calendar method (counting cycle days)
- - Basal body temperature charting
- - Cervical mucus observation
- - Ovulation predictor kits (LH surge detection)
- - Symptothermal method (combining multiple signs)
Conception Tips
For couples trying to conceive, timing intercourse within the fertile window is key. Having intercourse every one to two days during the five days before ovulation and on the day of ovulation itself maximizes the chances of conception. For healthy couples under 35, there is approximately a 20 percent chance of conceiving each cycle, and most couples conceive within 6 to 12 months of trying. If you are under 35 and have not conceived after 12 months, or if you are 35 or older and have not conceived after 6 months, consider consulting a fertility specialist.
Pregnancy Week Calculation
Formula (LMP Method):
Gestational Age (days) = Today's Date - LMP Date
Weeks = floor(Gestational Age / 7), Days = Gestational Age mod 7
Worked Example
Given: LMP was September 1, 2025. Today is December 15, 2025.
Step 1: Count total days from September 1 to December 15: 29 (Sep) + 31 (Oct) + 30 (Nov) + 15 (Dec) = 105 days.
Step 2: Weeks = floor(105 / 7) = 15 weeks. Days = 105 mod 7 = 0 days.
Step 3: Trimester: 15 weeks falls in the second trimester (weeks 13-27).
Step 4: Due Date = September 1 + 280 days = June 8, 2026.
Result: You are 15 weeks 0 days pregnant, in your second trimester, with an estimated due date of June 8, 2026.
Week-by-Week Development Milestones
| Week | Baby Size | Key Development | Trimester |
|---|---|---|---|
| 4 | Poppy seed (0.04g) | Implantation; neural tube begins forming | 1st |
| 8 | Raspberry (1g) | Heart beating; major organs forming | 1st |
| 12 | Lime (14g) | All major organs formed; reflexes developing | 1st |
| 16 | Avocado (100g) | Can hear sounds; gender detectable | 2nd |
| 20 | Banana (300g) | Halfway point; anatomy scan week | 2nd |
| 24 | Corn (600g) | Viability milestone; lungs developing | 2nd |
| 28 | Eggplant (1 kg) | Rapid brain development; eyes open | 3rd |
| 32 | Coconut (1.7 kg) | Bones hardening; major weight gain | 3rd |
| 36 | Papaya (2.6 kg) | Lungs nearly mature; considered early term | 3rd |
| 40 | Watermelon (3.4 kg) | Fully developed; ready for birth | 3rd |
Important Disclaimer
This pregnancy week calculator is intended for educational and informational purposes only. The gestational age and due date estimates provided are approximations based on standard calculation methods and may not precisely reflect your individual pregnancy. Fetal development varies from one pregnancy to another, and the milestones listed represent general averages.
This tool should not replace professional medical advice. Always attend your scheduled prenatal appointments and consult your obstetrician, midwife, or healthcare provider for an accurate assessment of your pregnancy progress, especially if you have any concerns about your health or your baby's development.