OB Wheel

hCG doubling-time calculator

Enter two hCG blood results and their dates to see the doubling time and daily rise. This is an educational snapshot only — hCG must be interpreted by your clinician, never from a calculator alone.

How to use it

1 Enter first result +date 2 Enter second result+ date 3 Read doubling time 4 Discuss with yourclinician
  1. Enter your first blood hCG value and its date. Use the quantitative (beta) hCG number from a blood test, in mIU/mL.
  2. Enter the second value and its date. The two tests are usually a couple of days apart.
  3. Read the doubling time and daily rise. The tool shows how quickly the level is rising and how that compares, loosely, to the early-pregnancy range.
  4. Take the number to your provider. A calculator can’t diagnose. Your clinician interprets hCG alongside your dates, symptoms and, when needed, an ultrasound.

What doubling time means

Rather than any single value, clinicians often look at whether hCG is rising appropriately across two readings. Early on, a rise of roughly 48–72 hours per doubling is common, but the normal range is wide and doubling slows as levels climb. For the full picture, see hCG levels and doubling time.

Interpret with your clinician. This tool describes a trend; it does not diagnose a viable or non-viable pregnancy. A flat or falling level, pain, or bleeding should prompt a call to your provider.

Frequently asked questions

How do you calculate hCG doubling time?

From two blood hCG values and the hours between them. The doubling time is the hours multiplied by ln(2), divided by the natural log of the ratio of the two values — the tool does this for you.

What is a normal hCG doubling time?

In early pregnancy hCG often roughly doubles every 48 to 72 hours. Doubling naturally slows as levels get higher, so that range applies mainly to the early weeks and to lower values.

My hCG isn't doubling — should I worry?

A slower rise has several possible explanations and can't be interpreted by a calculator. A rise that is flat or falling should be discussed with your clinician promptly. Always interpret hCG with your provider.

Can a home test show my hCG level?

No. Home urine tests give a yes/no result, not a number. Doubling time needs quantitative blood tests, repeated a couple of days apart through a clinic.

Does hCG tell me how far along I am?

Not reliably. hCG ranges at any point are very wide, so it can't date a pregnancy. Use your last period, an ultrasound, or a known conception or IVF date in the due-date calculator instead.