About

Monitoring beta-human chorionic gonadotropin (hCG) is a standard method for assessing early pregnancy viability. While a single reading confirms pregnancy, the trajectory relative to gestational age offers clinical insight into progression. This tool maps user-provided blood test results onto a logarithmic scale against reference ranges established by the American Pregnancy Association. This visualization helps distinguish between expected physiological ranges and outliers that may warrant medical consultation.

The range of normal hCG values is extremely wide and grows exponentially in the first trimester. For example, week 4 values can range from 5 to 426 mIU/mL, while week 5 ranges from 18 to 7,340 mIU/mL. Because of this massive variance, linear charts often fail to display the data meaningfully. This calculator utilizes a semi-log plotting method to accurately place your specific value within the broad bands of singleton pregnancy statistics.

Formulas

The calculator compares the input value y against the minimum min and maximum max thresholds for a given week t. The visualization uses a logarithmic transformation due to the exponential nature of hormone production.

y_plot = log₁₀(hCG)

Standard Reference ranges are derived from singleton pregnancies. Values for multiple gestations (twins/triplets) often track 30&percent; to 50&percent; higher but still overlap significantly with singleton ranges.

Reference Data

Gestational Age (LMP)	hCG Range (mIU/mL)	Median Value	Physiological Milestones
3 Weeks	5 − 50	17	Implantation occurs
4 Weeks	5 − 426	141	Missed Period
5 Weeks	18 − 7,340	1,325	Gestational Sac visible (TVUS)
6 Weeks	1,080 − 56,500	12,400	Yolk Sac / Fetal Pole
7 − 8 Weeks	7,650 − 229,000	68,600	Heartbeat detectable
9 − 12 Weeks	25,700 − 288,000	85,000	Peak hCG levels
13 − 16 Weeks	13,300 − 254,000	48,000	Placenta takes over
17 − 24 Weeks	4,060 − 165,400	25,000	Second Trimester baseline
25 − 40 Weeks	3,640 − 117,000	18,000	Third Trimester maintenance

Frequently Asked Questions

The onset of implantation varies by up to 5 days between individuals. Since hCG doubles approximately every 48 hours, a difference of 3 days in implantation can result in one healthy pregnancy having an hCG of 50 while another is at 200. Both are normal; the rate of rise is more important than the absolute number.

LMP stands for Last Menstrual Period. In clinical obstetrics, pregnancy dating starts from the first day of the last period, not the day of conception. This is typically 2 weeks before ovulation. If you know your ovulation date (DPO), add 14 days to convert to LMP gestational age.

While higher median levels are associated with multiple gestations, the ranges overlap heavily. A singleton pregnancy can have a value of 1,000 mIU/mL at 5 weeks, and a twin pregnancy can have the same. Ultrasound is the only definitive method to confirm multiples.

Values below the reference range may indicate incorrect dating (you are less pregnant than calculated), a chemical pregnancy, or an ectopic pregnancy. However, a single low reading is inconclusive. Physicians typically order a repeat test in 48 hours to check doubling time.