hCG Levels Calculator
Calculate expected hCG doubling time and compare your levels to typical early pregnancy ranges. hCG (human chorionic gonadotropin) typically doubles every 48-72 hours in early healthy pregnancy.
Formula & Reference
| Variable | Symbol | Formula | Units |
|---|---|---|---|
| hCG Levels Calculator | — | Healthy hCG roughly doubles every 48-72 hours (early pregnancy) | mIU/mL |
Step-by-Step Examples
First test: 100 mIU/mL. Second test 48 hours later: 220 mIU/mL.
- Ratio = 220/100 = 2.2x
- Doubling time = 48×ln(2)/ln(2.2) = 48×0.693/0.788 = 42.2 hours
- Within or faster than the typical 48-72 hour range — reassuring early pattern
First test: 500 mIU/mL. Second test 48 hours later: 750 mIU/mL.
- Ratio = 750/500 = 1.5x
- Doubling time = 48×ln(2)/ln(1.5) = 48×0.693/0.405 = 82.1 hours
- Slower than typical — clinical correlation needed, may still be normal especially at higher hCG levels where doubling naturally slows
First test: 300 mIU/mL. Second test 48 hours later: 250 mIU/mL.
- Ratio = 250/300 = 0.83x (decrease)
- Declining levels are a different clinical situation than slow rise
- Always requires prompt clinical evaluation
Real-World Applications
Common Mistakes to Avoid
hCG levels vary enormously between individuals at the same gestational age — they're not reliable for precise dating, only general pregnancy detection and trend monitoring.
Doubling time naturally slows as hCG levels rise (especially above 1200-2000 mIU/mL) — this is normal and doesn't necessarily indicate a problem.
hCG trends are just one piece of clinical information — ultrasound findings, symptoms, and overall clinical context are essential and require professional medical evaluation.