Fetal Weight Calculator
See the average weight and length for each week of pregnancy.
Enter the first day of your last period and we'll show the average fetal weight and length for your current week, plus the full week-by-week chart from week 8, when there's enough there to measure, through week 42. These are population averages, not a measurement of your baby specifically, an ultrasound is the only way to get that.
Weights and lengths are averages from standard fetal growth references, individual babies vary quite a bit and still fall within a normal range. Length is measured crown to rump (head to bottom) through about week 20, when the legs are still curled up, then head to heel afterward, which is why the length jumps between those weeks rather than climbing smoothly.