hCG doubling time calculator
Enter two beta hCG results and how many hours apart they were taken. You'll get the doubling time and the 48-hour rise that clinicians look at.
- Equivalent 48-hour rise
- 108%
- Typical early-pregnancy doubling
- 48–72 h
This is arithmetic, not a diagnosis. Only your clinician can interpret hCG in context with symptoms and a scan.
What "doubling" looks like
If your levels kept doubling at the rate you entered, here is where they would be every 48 hours. Real hCG growth slows down as levels rise, which is why doubling time is most useful below about 6,000 mIU/mL.
Frequently asked questions
What is a normal hCG doubling time?
In early pregnancy, hCG levels in a viable pregnancy typically double every 48–72 hours. The rise slows as levels climb: above about 1,200 mIU/mL doubling often takes 72–96 hours, and above 6,000 mIU/mL it slows further. Levels peak around 8–11 weeks and then fall.
What is the minimum normal rise in 48 hours?
Research by Barnhart and colleagues found that most viable intrauterine pregnancies rise by at least 35–50% over 48 hours, depending on the starting level. A slower rise doesn't prove a problem, but it is a reason for your clinic to follow up with another test or an ultrasound.
Is one hCG number enough?
No. The normal range for a single hCG result is very wide. What matters is the trend over 48–72 hours, interpreted alongside symptoms and ultrasound findings by your clinician.
Can hCG be too high?
Higher-than-average levels are common in healthy pregnancies and with twins. Very high levels can occasionally point to a molar pregnancy, which is diagnosed by ultrasound.
Sources: Barnhart et al., Obstetrics & Gynecology 2004 and 2016, on hCG rise in viable pregnancies; ACOG Practice Bulletin 193 (tubal ectopic pregnancy).