Pregnancy Calculator

A pregnancy calculator is a date-estimation tool. It does not determine the exact moment of fertilization or guarantee a birth date. The standard LMP approach counts pregnancy from the first day of the last menstrual period and uses approximately 40 weeks, or 280 days, as the estimated gestational length. This is the convention used by many clinical due-date calculators. citeturn0search3

1. LMP method

Enter the first day of the last menstrual period. The calculator adds 280 days for a 28-day cycle. If you select cycle adjustment, the estimate is shifted by the difference between your cycle length and 28 days. This is an estimate, particularly when cycles are irregular.

2. Due-date method

If a clinician has already provided an estimated due date, the tool works backward to estimate the current gestational age and other timeline dates. It should not be used to override the date established by your maternity-care team.

3. Conception method

When a conception date is known or estimated, the calculator adds approximately 266 days to estimate the due date. Conception is not usually known to the exact day in natural pregnancies, so this method should be treated as an estimate.

4. Ultrasound method

If you know the date of an ultrasound and the gestational age reported at that scan, the calculator projects the estimated due date from that information. Early dating ultrasound can be useful when the LMP is uncertain; the NHS notes that a 12-week scan can more accurately estimate how many weeks pregnant someone is. citeturn0search2

5. IVF transfer method

For IVF, the embryo transfer date and embryo age can be used to estimate the pregnancy timeline. This is a useful option because the transfer date is known. Clinical fertility records should remain the primary reference.

Gestational age versus fetal age

Gestational age is conventionally counted from the first day of the last menstrual period, not from fertilization. That means the “pregnancy week” can be about two weeks ahead of the biological age of the embryo in a typical cycle. Calculator.net similarly explains the distinction between gestational age and conception. citeturn0search0

Trimester calculation

The tool groups the timeline into three broad trimesters for easy understanding. Trimester boundaries are approximate educational markers and should not be interpreted as clinical cutoffs for individual care.

Why due dates can change

A due date is an estimate rather than a promise. Pregnancy normally lasts around 37 to 42 weeks from the first day of the LMP, and many births occur before or after the estimated date. citeturn0search2turn0search15

What makes this tool more useful

DigiSadhan combines several common dating inputs, transparent calculation steps, cycle-length adjustment, milestone visualization and mobile-friendly controls. The result card shows the estimated due date, current gestational age, trimester, approximate conception window, days remaining and a visual pregnancy progress indicator.

Accuracy and limitations

Date calculations are mathematically reproducible, but the underlying dates may be uncertain. LMP recall can be wrong, ovulation can vary, cycles can be irregular, and natural conception cannot usually be assigned to one exact day. Ultrasound dating and clinician assessment may be more appropriate when dates are uncertain.

Important safety information

This calculator is not a medical device and cannot diagnose pregnancy, determine fetal health, assess viability, identify complications or replace prenatal care. If you have bleeding, severe abdominal pain, fainting, severe headache, reduced fetal movement later in pregnancy, or another urgent concern, contact an appropriate healthcare professional or emergency service rather than relying on an online calculator.

Privacy-friendly design

The calculator performs its calculations in the browser and does not require an account. Avoid entering information you do not need for the calculation.

For women and families

The interface uses gentle, celebratory animations—floating hearts, a soft pulse, sparkles and a growing pregnancy-progress ring—to make the timeline welcoming without turning health information into a game. You can disable animations from Advanced Controls.