hCG Levels Calculator & Chart
hCG Levels Chart by Week: Beta-hCG Ranges and Doubling Time
HCG (human chorionic gonadotropin) is a pregnancy-specific placental hormone detectable in blood about 8–11 days after ovulation and in urine around 10–14 days after conception. In early viable pregnancy, levels typically double every 48–72 hours until approximately 6–7 weeks’ gestation, then rise more slowly thereafter.
Doubling Time Formula in hCG Levels Calculator
Example: hCG is 1,200 mIU/mL at hour 0 and 2,500 mIU/mL at hour 48.
- ln(2) × 48 = 33.27
- ln(2,500) − ln(1,200) = 7.824 − 7.090 = 0.734
- Doubling time = 33.27 ÷ 0.734 ≈ 45 hours
Use serial values, not a single reading
One hCG value cannot confirm viability or location, because normal ranges overlap widely across gestational ages and individuals. Interpretation depends on:
Rate of Change Across Serial Draws
Accurate clinical interpretation requires measuring two or more draws precisely 48 hours apart. Crucially, testing must be performed at the same clinical laboratory using the identical assay platform to prevent inter-assay measurement discrepancy.
Initial Starting hCG Baseline
A slower physiological rise is standard at higher baselines. Evidence-based thresholds (Barnhart et al., 2016) define minimum expected 48-hour rises in viable intrauterine pregnancies:
Ultrasound Correlation & Discriminatory Zone
Once beta-hCG values attain the discriminatory threshold (conventionally 1,500–2,000 mIU/mL, extending up to 3,500 mIU/mL per contemporary ACOG guidance), transvaginal ultrasound directly supersedes lab doubling curves to verify an intrauterine gestational sac.
The doubling formula is valid for early pregnancy when the rise is approximately exponential, generally below about 6,000 mIU/mL. After that, the rise slows and doubling time stops being a useful measure.
Weekly Beta-hCG Reference Ranges
Weeks are completed weeks from LMP. DPO is days past ovulation, assuming day-14 ovulation. Ranges are widely published reference intervals and vary between laboratories.
| Weeks from LMP | Days Past Ovulation (DPO) | Normal Beta-hCG Range (mIU/mL) | Typical Doubling Speed |
|---|---|---|---|
| 3 weeks | 7–13 | 5 – 72 | Rise begins post-implantation |
| 4 weeks | 14–20 | 10 – 708 | Every 48–72 hours |
| 5 weeks | 21–27 | 217 – 8,245 | Every 48–72 hours |
| 6 weeks | 28–34 | 152 – 32,177 | Every 72–96 hours |
| 7 weeks | 35–41 | 4,059 – 153,767 | Slowing (~96 hours+) |
| 8 weeks | 42–48 | 31,366 – 149,094 | Approaching plateau |
| 9 weeks | 49–55 | 59,109 – 135,901 | Peak plateau |
| 10 weeks | 56–62 | 44,186 – 170,409 | Peak plateau |
| 11–12 weeks | 63–76 | 27,107 – 201,615 | Peak, then begins decline |
| 13–14 weeks | 77–90 | 24,302 – 93,646 | Declining |
| 15–16 weeks | 91–104 | 8,904 – 69,747 | Declining |
| 17–18 weeks | 105–118 | 8,240 – 55,271 | Declining |
| 19–24 weeks | 119–160 | ~3,000 – 50,000 | Low, stable plateau |
| 25–40 weeks | 161–266 | ~1,000 – 50,000 | Low, stable plateau |
hCG typically peaks between weeks 9 and 12, then falls to a lower plateau for the rest of pregnancy. Use the Conception Date vs. LMP tool to confirm your week count, and the Pregnancy Trimester Timeline for context.
Clinical Red Flags and Deviations
Abnormally Slow Rise or Plateau
A rise below the minimum expected for the starting level, a plateau, or a decline warrants clinical evaluation for:
Ectopic pregnancy
Often presents with a subnormal rise, though up to about half of ectopic pregnancies show a rise in the normal range. Pain, vaginal bleeding, or dizziness requires same-day evaluation.
Early pregnancy loss
Falling or plateauing hCG is consistent with a nonviable intrauterine pregnancy.
Exceptionally elevated hCG Levels Calculator.
Molar pregnancy (gestational trophoblastic disease)
hCG often exceeds 100,000 mIU/mL before 12 weeks, sometimes with severe nausea, early preeclampsia signs, or heavy bleeding. Diagnosis requires ultrasound and pathology.
Multiple gestation
Twins and triplets tend to have higher mean hCG, but ranges overlap with singletons, and hCG cannot diagnose multiples.
Incorrect dating can also make hCG appear “high” or “low” for the stated week.
Frequently Asked Questions
What is considered a good hCG doubling rate? I
In early pregnancy with an initial level below about 1,500 mIU/mL, doubling every 48–72 hours is typical, and a rise of at least about 49% in 48 hours is the minimum expected for viable pregnancy. A slower rise does not by itself prove a problem, so clinicians use serial values with ultrasound.
Can high hCG mean twins?
It can be associated with twins, but hCG alone cannot diagnose a multiple pregnancy. Normal singleton ranges are very wide and overlap with twin values. Ultrasound confirms the number of fetuses.
At what hCG level can an ultrasound detect a gestational sac?
A transvaginal ultrasound can usually detect an intrauterine gestational sac when hCG is about 1,500–2,000 mIU/mL, the traditional “discriminatory zone.” Current ACOG guidance notes the zone may be as high as 3,500 mIU/mL to avoid misdiagnosing a viable early pregnancy, so no sac at lower levels is not diagnostic of a problem.
Why do at-home urine pregnancy tests show positive at lower hCG levels?
Home tests are designed to detect hCG at about 20–25 mIU/mL, and sensitive tests can detect lower. Blood assays detect as low as about 1–5 mIU/mL. Urine tests are usually reliable by the first day of a missed period, about 14 DPO. Urine concentration, dilution, and test brand affect when a positive appears.