hCG Doubling Time Calculator
hCG Doubling Time
Calculate the doubling time of hCG levels between two blood draws to assess early pregnancy viability
mIU/mL
mIU/mL
hours
Formula
Doubling Time = (Hours Between Tests x ln(2)) / ln(Second Level / First Level)
Frequently Asked Questions
What is a normal hCG doubling time?
In early pregnancy, hCG levels typically double every 48 to 72 hours. Doubling times slower than 72 hours may warrant further evaluation but do not always indicate a problem.
When do hCG levels stop doubling?
hCG levels rise rapidly in the first 8 to 11 weeks of pregnancy, then plateau and gradually decline for the rest of the pregnancy. After about 6,000 mIU/mL, doubling slows naturally.