Pregnancy Calculator

About the Pregnancy Calculator

This Pregnancy Calculator estimates your current pregnancy week (gestational age) and estimated due date (EDD) based on the first day of your last menstrual period (LMP). It is a convenient tool for expectant parents and caregivers to track pregnancy progress and plan ahead. The results are estimates only; your healthcare provider may adjust the due date using ultrasound or other clinical information.

How to Use

Enter the first day of your last menstrual period (the first day of your last period before you became pregnant). The calculator will show your current week of pregnancy and your estimated due date. Pregnancy is typically counted as 40 weeks (280 days) from the LMP. If you are unsure of your LMP or have irregular cycles, an early ultrasound can help establish or correct your due date; your doctor or midwife can guide you.

• Enter the first day of your last menstrual period.
• View your current pregnancy week and estimated due date.
• Use the information to track progress and plan appointments.

Why the Due Date Is an Estimate

Only a small percentage of babies are born exactly on the calculated due date. Most arrive within a window of about two weeks before or after. The LMP-based method assumes a 28-day cycle and ovulation around day 14; irregular cycles or later ovulation can shift the real due date. Early ultrasound (first trimester) is often used to refine the EDD. Your healthcare team will use the most accurate date available for your care.

Pregnancy Trimesters

Pregnancy is commonly divided into three trimesters. The first trimester is weeks 1–13 and includes early development and often the first prenatal visits. The second trimester is weeks 14–27, when many people feel more energy and may have anatomy scans. The third trimester is weeks 28–40 (or until birth), when the baby grows and prepares for delivery. Knowing your current week helps you understand which stage you are in and what to expect.

How to Use This Pregnancy Calculator

Enter the first day of your last menstrual period (LMP) or your due date if known. The Pregnancy Calculator estimates due date (typically 40 weeks from LMP), current week, and trimester. Use it for planning and awareness only; it does not replace clinical care. Due dates are estimates; your provider may adjust based on ultrasound or other factors. This tool is for informational use only.

When Pregnancy Dating Helps

Knowing your week and due date helps with appointments and screening windows. Always rely on your doctor or midwife for official dating and care. This tool is for general reference only.

Preterm and Post-Term

Birth before 37 weeks is generally considered preterm; after 42 weeks, pregnancy is often described as post-term. Preterm and post-term births may need extra monitoring or care. This calculator does not replace clinical assessment. Always follow the guidance of your doctor or midwife for due date, screening, and delivery planning.

How the Due Date Is Computed

The calculator uses Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a 28-day cycle and ovulation around day 14. In practice, cycle length and ovulation vary; early ultrasound (e.g. crown–rump length in the first trimester) is often used to adjust the due date. Some calculators use LMP + 280 days; others may offer an option based on conception date or IVF transfer date. This tool is for informational use only; your provider may use a different method or adjust based on clinical findings.

Limitations

LMP-based dating is less accurate if your cycles are irregular, if you are unsure of your LMP, or if you ovulated significantly earlier or later than day 14. Assisted reproduction (IVF, IUI) may use transfer or retrieval dates instead. This calculator does not account for high-risk factors, multiples, or medical history. Always use your healthcare provider's confirmed due date and week for appointments and screening. This tool is for general reference only and is not a substitute for medical advice.

How to Use This Calculator

Enter the first day of your last menstrual period (LMP). The tool adds 280 days (or 40 weeks) to estimate your due date and shows your current pregnancy week. Use it for planning and reference only; your doctor or midwife may assign a different date after examination or ultrasound. For IVF or IUI, use transfer or retrieval dates if your tool supports them. This calculator is for informational use only.

Important Disclaimer

This tool is for informational use only. It does not provide medical advice, diagnosis, or treatment. Pregnancy and due date should be confirmed and managed by a qualified healthcare provider. If you have questions about your dates, cycle, or pregnancy health, consult your doctor or midwife.