Blood Pregnancy Test (hCG) Calculator

mIU/mL
mIU/mL
h
Health

Track how your blood pregnancy test (quantitative beta-hCG) is changing between two draws. Enter your two hCG values and the hours between them, and this calculator returns the doubling time and the percentage rise.

Rates and fees change frequently. Always confirm the current figures with the official authority before relying on this result.

Formula

Doubling time = (hours × ln 2) ÷ ln(hCG₂ ÷ hCG₁)
  • A blood pregnancy test measures quantitative beta-hCG; in early pregnancy this hormone normally rises steadily.
  • Doubling time is the hours it would take hCG to double at the rate observed between your two values.
  • In a typical early intrauterine pregnancy, hCG roughly doubles every 48–72 hours.
  • Percentage change shows the rise between the two draws; a rise of at least ~35% over 48 hours is often considered reassuring.
  • A single pair of values is not diagnostic — trends, ultrasound, and clinical context matter, so interpret results with your provider.

100 to 200 mIU/mL over 48 hours

Inputs
  • First hCG Value: 100 mIU/mL
  • Second hCG Value: 200 mIU/mL
  • Hours Between Tests: 48 h

Going from 100 to 200 in 48 hours is a 100% rise with a doubling time of exactly 48 hours — a textbook early-pregnancy increase.

Frequently asked questions

What is a blood pregnancy test?
It is a quantitative beta-hCG test that measures the exact level of pregnancy hormone in your blood, unlike a urine test that only shows positive or negative.
How fast should hCG rise?
In early pregnancy hCG typically doubles about every 48–72 hours. A rise of at least 35–50% over two days is often considered normal.
What does doubling time tell me?
It estimates how quickly hCG is increasing. A shorter doubling time means faster rise; very slow or falling levels may need closer evaluation.
What if my hCG isn't doubling?
Slow-rising, plateauing, or falling hCG can have several causes and should be assessed by your clinician alongside symptoms and ultrasound.
Can hCG be too high?
Very high or unusually fast-rising levels can occur in normal pregnancies (including multiples) but sometimes warrant follow-up. Your provider interprets the full picture.