In a healthy early pregnancy, hCG typically doubles every 48–72 hours until about 6–7 weeks. A rise of at least 35–50% in 48 hours is expected in most viable intrauterine pregnancies; slower rises or falls need follow-up to rule out miscarriage or ectopic pregnancy.
How to use the hCG Levels Calculator
- First hCG
- Second hCG
- Hours between tests
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the two hCG results and the number of hours between the blood tests.
Inputs explained
| Field | What to enter |
|---|---|
| First hCG | In mIU/mL |
| Second hCG | In mIU/mL |
| Hours between tests | In h |
Example values
How the main result changes when First hCG changes and everything else stays at the example values above:
| First hCG (mIU/mL) | Doubling time (hours) |
|---|---|
| 60 | 23 |
| 90 | 31 |
| 120 | 43 |
| 150 | 60 |
| 180 | 90 |
| 240 | 416 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Doubling time (h) = t × ln 2 ÷ ln(hCG₂ ÷ hCG₁)
48-hour rise (%) = ((hCG₂ ÷ hCG₁)⁴⁸ ÷ t) − 1) × 100
Worked example
Inputs — First hCG: 120 mIU/mL; Second hCG: 260 mIU/mL; Hours between tests: 48 h.
Results — Doubling time = 43 hours; Rise over 48 hours = 117 %; Interpretation = Rise consistent with a progressing early pregnancy.
Key terms
- hCG
- Human chorionic gonadotropin.
Frequently asked questions
How fast should hCG rise?
Usually doubling every 48–72 hours in the first weeks.
Does hCG keep doubling?
No – the rise slows after about 6–7 weeks and peaks at 8–11 weeks.
Can one hCG value tell me if the pregnancy is OK?
Not on its own; the trend and an ultrasound are needed.