🔍 /

Fetal Development & Size Calculator

Estimate fetal weight and length based on WHO and CDC growth percentiles. Features fruit comparisons and gestational age calculation from LMP or conception date.

User Rating 0.0 ★★★★★
Total Usage 1 times
Category Women\'s Health
Is this tool helpful?

Your feedback helps us improve.

★ ★ ★ ★ ★

About

Accurate estimation of fetal growth is essential for monitoring pregnancy progression and identifying potential intrauterine growth restrictions (IUGR) or macrosomia early. This tool utilizes data from the World Health Organization (WHO) and Centers for Disease Control (CDC) to project fetal weight and crown-rump length (CRL) or crown-heel length (CHL) depending on the gestational stage.

Unlike generic trackers, this calculator provides specific percentile ranges (5th, 50th, 95th), offering a statistical context for the measurements. It correlates these metrics with tangible object comparisons to assist in visualizing physical scale. The calculation logic adjusts for standard gestation periods (40 weeks) and allows differentiation between Last Menstrual Period (LMP) and precise Conception Date inputs.

pregnancy fetal growth gestational age due date percentiles

Formulas

Gestational Age (GA) is calculated based on the difference between the current date (Dcurr) and the Last Menstrual Period (Dlmp).

GAdays = Dcurr − Dlmp

If Conception Date (Dcon) is used, an arbitrary 14 days are added to align with clinical standards.

GAdays = (Dcurr − Dcon) + 14

Reference Data

Gestational AgeAvg Weight (50th %ile)Avg Length (50th %ile)Object Comparison
8 Weeks1.0 g1.6 cmRaspberry
12 Weeks14.0 g5.4 cmPlum
20 Weeks300 g25.6 cmBanana
28 Weeks1005 g37.6 cmEggplant
36 Weeks2622 g47.4 cmPapaya
40 Weeks3500 g51.2 cmPumpkin

Frequently Asked Questions

In early pregnancy (up to approx. 14-20 weeks), fetuses are measured from the top of the head (crown) to the bottom of the buttocks (rump) because the legs are curled. Later, as the fetus extends, the medical standard switches to Crown-Heel length.
The 50th percentile represents the median average. The 5th percentile suggests the fetus is smaller than 95% of others at the same gestational age, while the 95th means it is larger than 95%. Consistent tracking is more important than a single data point.
LMP-based calculations assume a standard 28-day cycle with ovulation on day 14. First-trimester ultrasounds are generally considered the most accurate method for dating a pregnancy (dating scan). This tool provides estimates based on statistical averages.