Medically reviewed by Samantha L. Fox, RN, BSN, MSN
Nursing Informaticist ยท United States Navy Nurse Corps ยท Last reviewed
Quantitative hCG Calculators
Four research-driven tools for interpreting beta hCG: doubling time in early pregnancy, reference ranges by gestational week, single-value gestational age estimation, and post-loss / post-methotrexate decline tracking. Built and clinically reviewed for patients trying to make sense of their lab results between appointments.
When to skip the calculator and call 911 / go to the ED:
Any pelvic or abdominal pain (especially one-sided), heavy bleeding (soaking a pad per hour), shoulder-tip pain, dizziness, fainting, fever, or a sense that something is seriously wrong. These can be symptoms of ectopic pregnancy, which is a surgical emergency โ and ectopic pain is not always severe at first. No calculator is more important than how you feel.
hCG Doubling Time Calculator
Enter two quantitative beta hCG values and the date/time of each blood draw. Most useful in early pregnancy (roughly 1,200-6,000 mIU/mL).
Units note: US labs report hCG as mIU/mL (milli-international units per milliliter). Some labs print IU/L (international units per liter) โ the number is identical: 1 mIU/mL = 1 IU/L. Use whichever your lab report shows.
First draw
Second draw
hCG Reference Ranges by Gestational Week
Standard reference ranges for serum quantitative hCG, measured from the first day of the last menstrual period (LMP). Ranges are intentionally wide because individual variation between healthy pregnancies is enormous โ the trend across serial draws matters far more than any single number falling inside or outside the range.
All values in mIU/mL (= IU/L; same number, different label).
| Gestational age | hCG range (mIU/mL) |
|---|---|
| 3 weeks LMP | 5.0 โ 50 |
| 4 weeks LMP | 5.0 โ 426 |
| 5 weeks LMP | 18 โ 7,340 |
| 6 weeks LMP | 1,080 โ 56,500 |
| 7-8 weeks LMP | 7,650 โ 229,000 |
| 9-12 weeks LMP | 25,700 โ 288,000 |
| 13-16 weeks LMP | 13,300 โ 254,000 |
| 17-24 weeks LMP | 4,060 โ 165,400 |
| 25-40 weeks LMP | 3,640 โ 117,000 |
| Non-pregnant | 0.0 โ 5.0 |
Source: American Pregnancy Association reference values, consistent with common hospital lab reference panels. Some labs publish narrower ranges; always compare your result to the reference range printed on your specific lab report.
This tool is intentionally low precision โ please read.
A single hCG number cannot reliably tell you how far along you are. Published reference ranges for hCG by gestational week overlap by an order of magnitude โ a value of 7,000 mIU/mL is consistent with anywhere from 5 to 8 weeks LMP, and individual healthy pregnancies vary that widely at the same gestational age.
Use this tool only for orientationโ for example, checking whether your result is in the โdefinitely pregnantโ range. Do not use it to date a pregnancy, plan around a presumed timeline, or replace an ultrasound. ACOG does not endorse single-value hCG for gestational age estimation.
For dating, use the Due Date Calculator (ultrasound mode) or the Conception Date Calculator.
Sensitive tool โ for tracking hCG after pregnancy loss or treatment
This tool is designed for situations where hCG is expected to fall โ after miscarriage, completed early pregnancy loss, D&C, or methotrexate treatment for ectopic pregnancy. We know that's a hard place to be in. We built this carefully because many patients are sent home with serial-hCG instructions and want to make sense of the numbers between draws.
This calculator does not diagnose anything.It calculates the half-life of your falling hCG and compares it to research-derived expected ranges. It cannot tell you whether retained tissue is present, whether a methotrexate dose worked, or whether another intervention is needed. Those decisions are your provider's.
If you have heavy bleeding, severe pain, fever, or feel unwell, contact your provider or go to the ED โ even if your numbers look reassuring on the calculator.
About these calculators
Why we built four tools, not one
Quantitative hCG is interpreted very differently depending on context. A 600 mIU/mL value at 5 weeks rising to 1,400 over 48 hours is a textbook reassuring early pregnancy. The same 600 โ 1,400 sequence after a confirmed miscarriage means something else entirely. We split the math into four context-specific tools so the interpretation matches the clinical situation.
Sources & methodology
Doubling-time math uses the standard exponential formula t2x = (ฮt ร ln 2) / ln(hCG2/hCG1). Half-life math is the symmetric form for declining values. Interpretation bands draw on:
- Barnhart KT et al. Symptomatic patients with an early viable intrauterine pregnancy: hCG curves redefined. Obstet Gynecol. 2004;104(1):50-55. (Established the minimum-rise threshold of 53% in 48 hours for the 1st-percentile viable IUP.)
- Kadar N, Caldwell BV, Romero R. A method of screening for ectopic pregnancy and its indications.Obstet Gynecol. 1981;58(2):162-166. (Original 48-72h doubling-time benchmark.)
- Korhonen J et al. Disappearance of human chorionic gonadotropin and its alpha- and beta-subunits after term pregnancy. Clin Chem. 1997;43(11):2155-2163. (Half-life kinetics after pregnancy resolution.)
- ACOG Practice Bulletin No. 200 โ Early Pregnancy Loss. American College of Obstetricians and Gynecologists, 2018. (Clinical context for serial-hCG management.)
- American Pregnancy Association โ hCG levels by week (reference range table source).
A note on units
US laboratories report quantitative hCG in mIU/mL (milli-international units per milliliter), the standard unit for the WHO 5th International Standard for hCG. Some labs print the value as IU/L (international units per liter) โ these are numerically identical (1 mIU/mL = 1 IU/L), so use whichever your report shows. You will not see hCG reported in mg/dL, ng/mL, or pg/mL anywhere reputable โ those are mass-per-volume units used for analytes measured by mass (glucose, creatinine), not for hormones measured by immunoassay against an international activity standard.
What these tools cannot do
They cannot diagnose ectopic pregnancy. They cannot distinguish a normal pregnancy from a poorly developing one based on numbers alone. They cannot replace ultrasound โ once hCG is above the discriminatory zone (~1,500-2,000 mIU/mL), transvaginal ultrasound should show an intrauterine sac, and the absence of one changes the workup substantially. They cannot replace your provider's judgment, which integrates symptoms, exam, prior history, and imaging in addition to the numbers.
Useful tools while tracking hCG
Whether you're charting an early pregnancy or tracking after a loss, these are the things most patients reach for.
Log dates, values, and lab notes in one place.
For days you want a quick check between blood draws.
Symptom and appointment tracker for the first trimester.
Useful baseline if you're being monitored frequently.
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