Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Due Date Calculator

Calculates how many days remain until your estimated due date from how many days ago your last period (or conception) occurred, adjusting for cycle length or luteal phase.

Calculation Method

Days Since Last Period / Conception (days)

Average Cycle Length (days)

Luteal Phase Length (days)

Fill in the required fields to see your result.

Pregnancy

Baby Size Calculator

Estimates fetal weight and size using gestational age alone or ultrasound measurements (BPD, FL, AC). Used by parents and clinicians to track growth against standard developmental charts.

Gestational Age (weeks)

Additional Days (days) (optional)

Biparietal Diameter (BPD) (mm) (optional)

Femur Length (FL) (mm) (optional)

Abdominal Circumference (AC) (mm) (optional)

Fill in the required fields to see your result.

Key differences

	Due Date Calculator	Baby Size Calculator
Category	Pregnancy	Pregnancy
Inputs required	4	5
Result	Due Date Countdown	Estimated Baby Weight (grams)
What it does	Calculates how many days remain until your estimated due date from how many days ago your last period (or conception) occurred, adjusting for cycle length or luteal phase.	Estimates fetal weight and size using gestational age alone or ultrasound measurements (BPD, FL, AC). Used by parents and clinicians to track growth against standard developmental charts.