hCG Levels Calculator

Human chorionic gonadotropin (hCG) is a hormone produced by the placenta shortly after a fertilized egg implants in the uterus. It is the hormone detected by pregnancy tests, and rising hCG levels in the first trimester are a key sign of a healthy, progressing pregnancy. Blood tests measure hCG in mIU/mL and are more precise than urine-based home tests.

hCG can typically be detected in the blood as early as 6–10 days after fertilization, usually around the time of a missed period. Levels start very low — sometimes just 5–10 mIU/mL — and rise rapidly during the first 8–11 weeks of pregnancy. Urine tests can usually detect hCG around 12–15 days after ovulation.

In a healthy early pregnancy, hCG typically doubles every 48–72 hours during the first few weeks. After levels rise above roughly 6,000 mIU/mL, the doubling time naturally slows down and may take 72–96 hours or longer. A doubling time under 48 hours is considered excellent; over 96 hours may warrant further evaluation by your doctor.

hCG levels rise steeply from implantation until around weeks 8–11, when they typically peak between 25,000 and 200,000 mIU/mL or higher. After the peak, levels gradually decline and plateau for the remainder of pregnancy. The rate of rise is often more clinically meaningful than any single absolute value.

hCG levels generally reach their peak around 8–11 weeks of gestation and then begin to decline. By the second trimester, levels stabilize at a lower plateau. A slowdown in rise after the peak is completely normal and does not indicate a problem.

Low or slowly rising hCG levels can sometimes indicate an early pregnancy loss, ectopic pregnancy, or other complication — but they are not always cause for alarm on their own. Always consult your doctor or midwife if you are concerned about your hCG results. Serial tests over 48 hours provide much more information than a single reading.

Higher-than-expected hCG levels can occur with multiple pregnancies (twins, triplets), molar pregnancies, or simply normal variation. An elevated level alone is not necessarily concerning, but your healthcare provider may order an ultrasound or additional tests to investigate further.

This calculator uses the standard mathematical formula for exponential growth to compute hCG doubling time from two test values and the elapsed time between them. The results are for informational purposes only and should not replace professional medical advice. Always discuss your hCG results with your doctor or fertility specialist.