Baby Size Calculator by Week
Track your baby's size week by week with fruit comparisons. See how your baby is growing during pregnancy with size estimates and development milestones.
About This Baby Size Calculator
Our baby size calculator provides week-by-week size estimates using fruit and vegetable comparisons based on WHO international fetal growth standards. Track your baby's development from a poppy seed to a full-term baby, with detailed information about growth milestones and developmental changes throughout pregnancy.
References
- 1.
Papageorghiou, A.T., et al. (2014). International standards for fetal growth based on serial ultrasound measurements: The Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project. *The Lancet*, 384(9946), 869-879
- 2.
Villar, J., et al. (2014). International standards for newborn weight, length, and head circumference by gestational age and sex: The Newborn Cross-Sectional Study of the INTERGROWTH-21st Project. *The Lancet*, 384(9946), 857-868
- 3.
Hadlock, F.P., et al. (1991). In utero analysis of fetal growth: A sonographic weight standard. *Radiology*, 181(1), 129-133
- 4.
Mongelli, M., et al. (1996). Estimation of fetal weight in the third trimester: A review of ultrasound methods. *Journal of Maternal-Fetal Medicine*, 5(4), 172-174
- 5.
O'Rahilly, R., & Müller, F. (2010). Developmental stages in human embryos: Revised and new measurements. *Cells Tissues Organs*, 192(2), 73-84
- 6.
Sadler, T.W. (2015). Langman's Medical Embryology, 13th Edition. *Wolters Kluwer Health*
Frequently Asked Questions
Size estimates are based on WHO international standards and INTERGROWTH-21st research, but individual babies can vary significantly (±15-20%). These are general reference points - your healthcare provider will monitor your baby's actual growth through ultrasounds for the most accurate measurements.
Fruit and vegetable comparisons help visualize your baby's size in familiar terms. These comparisons are widely used because they provide relatable size references that are easy to understand and remember during pregnancy.
Crown-to-rump length (CRL) measures from the top of the head to the bottom of the torso and is used in early pregnancy. Later in pregnancy, measurements typically include total length from head to heel. CRL is more accurate in early pregnancy when babies are in a consistent position.
Your healthcare provider monitors growth patterns through regular ultrasounds and will alert you to any concerns. Consistent growth trends are more important than hitting exact size targets. Contact your doctor if you have specific concerns about your baby's development.
This calculator is designed for singleton pregnancies. Twin pregnancies have different growth patterns and require specialized monitoring by your healthcare provider. The size comparisons and timelines may not be accurate for multiple pregnancies.
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Medical Disclaimer: This tool provides educational estimates based on established formulas and is not intended as medical advice. Individual results may vary. For personalized guidance, consult with healthcare professionals through our platform.