how far along pregnancy calculator

How this pregnancy calculator works

A how far along pregnancy calculator estimates gestational age, usually in weeks and days. In clinical settings, pregnancy length is commonly counted as 40 weeks (280 days) from the first day of your last menstrual period (LMP), not from conception day.

That means if your pregnancy is listed as “8 weeks,” conception typically happened about 6 weeks ago. This can feel confusing at first, but it is the standard approach used in prenatal care.

What you can calculate here

• Your current pregnancy age in weeks and days
• Your estimated due date (EDD)
• Your estimated conception date
• Your trimester and percent progress toward 40 weeks
• How many days remain until your due date (or whether you are past due)

Which date should you use?

1) Last menstrual period (LMP)

If you know the first day of your last period, this is usually the best starting method for a general estimate. Most due date calculators and many providers use this at the beginning.

2) Estimated due date

If your doctor has already given you an EDD from ultrasound dating, use that date. The calculator will work backward to estimate your current week and your LMP equivalent.

3) Conception date

If you have a fairly specific conception date (for example, tracked ovulation or fertility treatment timing), the calculator can estimate gestational age by adding roughly two weeks to align with medical dating.

Understanding your result

Weeks + days format

Pregnancy progress is best shown as weeks and days (for example, 23 weeks + 4 days), not just “month 5.” This makes milestones and appointment timing more accurate.

Trimesters

• First trimester: 0 to 13 weeks + 6 days
• Second trimester: 14 to 27 weeks + 6 days
• Third trimester: 28 weeks to birth

Due date is an estimate

Only a small percentage of babies are born on the exact due date. Many full-term births happen within a range before or after the estimate. Your prenatal team will monitor growth and update care plans as needed.

Tips for better accuracy

• Use the earliest accurate date you have (LMP, ultrasound-based due date, or fertility treatment date).
• Double-check your date entry format before calculating.
• Recalculate after appointments if your clinician adjusts your due date.
• Keep all prenatal appointments to confirm fetal growth and timing.

Common questions

What if my cycles are irregular?

LMP-based estimates can be less precise with irregular cycles. Early ultrasound often provides the most reliable dating in that case.

Does this work for IVF pregnancy dating?

It can provide a quick estimate, but IVF pregnancies are typically dated using embryo transfer timing and clinical protocols from your fertility specialist.

Is this tool a diagnosis?

No. It is an informational calculator. If you have bleeding, pain, concerning symptoms, or uncertainty about dates, contact your healthcare provider promptly.

Final note

This tool is designed to make pregnancy timing easy to understand in plain language. Use it as a planning aid for appointments, milestones, and preparation—but rely on your clinician for final dating and medical guidance.