Compare a blood hCG level with published week-by-week reference ranges, or look up the typical hCG range for a pregnancy week. It cannot date a pregnancy.
Medical disclaimer: This calculator compares a value with published quantitative blood (serum) hCG reference rows; it does not estimate gestational age; it is not medical advice and cannot confirm viability, rule out ectopic pregnancy, or diagnose miscarriage. Reference ranges vary by lab/assay—use ultrasound and clinician guidance for dating and interpretation. Seek urgent medical care for heavy bleeding, severe or one-sided abdominal/pelvic pain, shoulder pain, dizziness/fainting, or severe worsening pain.
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HCG to Weeks Table (UCSF Health reference ranges; serum, mIU/mL)
| Gestational age (weeks) | Lower limit (mIU/mL) | Upper limit (mIU/mL) |
|---|---|---|
| 3 weeks | 5 | 72 |
| 4 weeks | 10 | 708 |
| 5 weeks | 217 | 8 245 |
| 6 weeks | 152 | 32 177 |
| 7 weeks | 4 059 | 153 767 |
| 8 weeks | 31 366 | 149 094 |
| 9 weeks | 59 109 | 135 901 |
| 10 weeks | 44 186 | 170 409 |
| 12 weeks | 27 107 | 201 165 |
| 14 weeks | 24 302 | 93 646 |
| 15 weeks | 12 540 | 69 747 |
| 16 weeks | 8 904 | 55 332 |
| 17 weeks | 8 240 | 51 793 |
| 18 weeks | 9 649 | 55 271 |
What Is HCG to Weeks?
HCG to weeks refers to the relationship between the level of human chorionic gonadotropin (hCG) and gestational age. hCG is a hormone produced by the developing placenta after implantation, and it can be detected in both urine and blood. In early pregnancy, hCG often rises rapidly (commonly increasing roughly every 48–72 hours during the first few weeks), then the rate of increase slows, and levels typically peak around about 8–10 weeks of gestation. Because hCG ranges overlap heavily from week to week and vary by lab and by person, a single hCG value cannot accurately date a pregnancy; ultrasound is the preferred method for pregnancy dating.
How to Calculate HCG to Weeks?
The following steps compare an hCG result with published reference rows. This is not a conversion to gestational age. The table comes from UCSF Health; ACOG identifies first-trimester ultrasound as the most accurate method for dating.
- Obtain a quantitative hCG blood test result (typically reported as mIU/mL; IU/L is numerically equivalent).
- Compare the hCG value to a reference table of typical ranges by gestational week (such as the UCSF Health ranges shown above).
- Report every published row containing the value, without treating the rows as possible ages or probabilities. Do not interpolate omitted weeks.
- For pregnancy assessment, interpret hCG with symptoms and (when appropriate) repeat testing to evaluate the trend; the rate of rise is not constant and varies widely.
- Confirm gestational age with ultrasound for the most reliable dating.
Example Problem:
Use the following variables as an example problem to test your knowledge.
HCG (mIU/mL) = 500
At 500 mIU/mL, the table rows for 4, 5 and 6 weeks all contain the value. These are reference-table matches, not an estimate that the pregnancy is 4–6 weeks old.
