Calculate Weeks And Days Pregnant

Pregnancy Calculation Formula:

\[ \text{Weeks} = \left\lfloor \frac{\text{Current Date} - \text{LMP}}{7} \right\rfloor \] \[ \text{Days} = (\text{Current Date} - \text{LMP}) \mod 7 \]

Pregnancy Duration:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Pregnancy Duration Calculation?

Pregnancy duration calculation determines how far along a pregnancy is by calculating the time elapsed since the first day of the last menstrual period (LMP). This is typically expressed in weeks and days.

2. How Does the Calculator Work?

The calculator uses the standard pregnancy dating formula:

\[ \text{Weeks} = \left\lfloor \frac{\text{Current Date} - \text{LMP}}{7} \right\rfloor \] \[ \text{Days} = (\text{Current Date} - \text{LMP}) \mod 7 \]

Where:

\( \text{LMP} \) — First day of last menstrual period
\( \text{Current Date} \) — Today's date or any specified date
\( \left\lfloor \right\rfloor \) — Floor function (round down)
\( \mod \) — Modulo operation (remainder)

Explanation: The calculation counts the total days between LMP and current date, then converts to weeks and remaining days.

3. Importance of Pregnancy Dating

Details: Accurate pregnancy dating is crucial for monitoring fetal development, scheduling prenatal tests, determining due date, and making important clinical decisions throughout pregnancy.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period and the current date (defaults to today). Ensure dates are entered in the correct format and that LMP date is before current date.

5. Frequently Asked Questions (FAQ)

Q1: Why is pregnancy calculated from LMP instead of conception?
A: LMP is used because it's a definite, observable date, while conception date is often uncertain. This provides a standardized method for pregnancy dating.

Q2: How accurate is LMP-based dating?
A: LMP dating is generally accurate for women with regular 28-day cycles. Ultrasound dating may be more accurate if cycles are irregular or LMP is uncertain.

Q3: What if I don't know my exact LMP?
A: If LMP is uncertain, an early pregnancy ultrasound (first trimester) provides the most accurate dating. Later ultrasounds are less reliable for dating.

Q4: Does this account for irregular cycles?
A: No, this calculator assumes a standard 28-day cycle. Women with irregular cycles may need ultrasound confirmation for accurate dating.

Q5: When should I see a healthcare provider?
A: Schedule your first prenatal appointment as soon as you suspect pregnancy, typically around 8 weeks gestation for initial assessment and confirmation.