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hCG calculator

Beta hCG doubling time calculator

Enter two blood hCG results and the time between them to see the doubling time and how much the level rose.

Updated

In short

How fast should hCG rise in early pregnancy?

In early pregnancy, blood hCG often doubles every two to three days, and the rise slows as levels get higher. A large 2016 study found the minimum 48-hour rise in pregnancies that continued normally was 49% from a first value under 1,500, 40% from 1,500 to 3,000, and 33% above 3,000. One result alone says little; the trend matters.

Time between the two tests

Calculated in your browser. Nothing is sent or saved.

Your estimate

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This is an estimate, not a diagnosis or birth control.

General information, not medical advice. Your doctor or midwife can tell you what your own results mean.

How it's calculated

  1. Doubling time = hours between tests × ln 2 ÷ ln(second result ÷ first result).
  2. Change over 48 hours = (second ÷ first)^(48 ÷ hours between) − 1.
  3. The minimum rises (49%, 40%, 33%) come from Barnhart and colleagues, 2016, by first value.
  4. Use results from the same lab where you can. Different labs can give slightly different numbers.

Gyne learns your real cycle and adjusts these estimates as you log.

Sources

  1. Barnhart KT et al. Differences in serum human chorionic gonadotropin rise in early pregnancy by race and value at presentation. Obstet Gynecol, 2016
  2. Pittaway DE et al. Doubling times of human chorionic gonadotropin increase in early viable intrauterine pregnancies. Am J Obstet Gynecol, 1985
  3. MedlinePlus: HCG blood test, quantitative

Frequently asked questions

What is a normal hCG doubling time?

In early pregnancy, often about 48 to 72 hours. It gets longer as hCG rises, and it varies between healthy pregnancies, so doctors look at the rise together with an ultrasound.

Can a single hCG level tell me if my pregnancy is healthy?

No. Healthy pregnancies have a wide range of hCG levels. Doctors compare two or more results, usually 48 hours apart, and use an ultrasound once hCG is high enough.

When should I get help right away?

Call your doctor or go to an emergency department if you have severe pain in your belly or shoulder, heavy bleeding, or you feel faint. In an emergency, call 911 or your local emergency number.

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