hCG Calculator
Calculate beta hCG doubling time and compare your levels to normal pregnancy ranges by gestational week
Enter your first beta hCG blood test result
Enter the date and time of your first blood draw
Enter your second beta hCG blood test result
Must be after the date and time of the first test
Enter Your hCG Values
Fill in your beta hCG measurements above and click Calculate to see your doubling time, percentage change, 48-hour projection, and clinical interpretation.
hCG Normal Ranges by Gestational Week
Based on widely cited obstetric references (MDApp, MomJunction, Mount Sinai). Ranges overlap substantially between individuals.
| Gestational Week | hCG Range (mIU/mL) |
|---|---|
| Not Pregnant | < 5 |
| 3 Weeks | 5 – 50 |
| 4 Weeks | 5 – 426 |
| 5 Weeks | 18 – 7,340 |
| 6 Weeks | 1,080 – 56,500 |
| 7–8 Weeks | 7,650 – 229,000 |
| 9–12 Weeks | 25,700 – 288,000 |
| 13–16 Weeks | 13,300 – 254,000 |
| 17–24 Weeks | 4,060 – 165,400 |
| 25–40 Weeks | 3,640 – 117,000 |
Expected Doubling Time by hCG Level
The expected doubling time varies as hCG rises — higher levels take longer to double.
| hCG Level | Expected Doubling Time |
|---|---|
| < 1,200 mIU/mL | 48 – 72 hours |
| 1,200 – 6,000 mIU/mL | 72 – 96 hours |
| > 6,000 mIU/mL | 96 – 144 hours |
Ultrasound Detection Thresholds
Typical hCG levels at which key structures become visible on ultrasound.
| Finding | Typical hCG (mIU/mL) |
|---|---|
| Gestational sac (transvaginal) | > 2,000 |
| Yolk sac (transvaginal) | > 2,500 |
| Embryo (transvaginal) | > 5,000 |
| Fetal heartbeat (transvaginal) | > 10,000 – 17,000 |
| Gestational sac (abdominal) | > 6,500 |
IVF / Embryo Transfer Reference
Typical hCG levels by day post embryo transfer (5-day blastocyst).
| Day Post Transfer | hCG Range (mIU/mL) |
|---|---|
| Day 9 | 1 – 30 mIU/mL |
| Day 10 | 2 – 60 mIU/mL |
| Day 11 | 4 – 80 mIU/mL |
| Day 12 | 17 – 119 mIU/mL |
| Day 13 | 50 – 200 mIU/mL |
| Day 14 | > 200 mIU/mL (ongoing); > 600 mIU/mL (likely multiples) |
How to Use the hCG Calculator
Choose Your Calculator Mode
Select Doubling Time mode if you have two beta hCG blood test results from different dates — this is the most common use case and gives the richest analysis. Select Level Lookup if you have a single result and want to compare it to normal weekly ranges. You can also set the unit to mIU/mL or IU/L (both are clinically equivalent, 1:1 ratio).
Enter Your hCG Values and Test Times
In Doubling Time mode, enter your first and second hCG results (in mIU/mL or IU/L). Then either enter the exact date and time of each blood draw using the date/time pickers, or enter the hours elapsed between tests manually. For the most accurate doubling time, use the exact date and time if you have them — even a few hours of difference significantly affects the calculation.
Review Your Results and Assessment
Click Calculate to see your doubling time in hours and days, the percentage change between draws, your projected 48-hour hCG level, one-day and two-day rise percentages, and a clinical assessment badge. The color-coded badge tells you whether your doubling time falls in the normal, slower-than-typical, or concerning range based on your starting hCG level. Ultrasound milestone alerts appear if your current hCG crosses a key detection threshold.
Use the Reference Tables and Copy Your Results
Scroll down to review the gestational week reference table, expected doubling times by hCG level, IVF transfer day ranges, and ultrasound detection thresholds. You can copy your full results summary to the clipboard with one click to share with your healthcare provider, or use the Print button to save a paper copy. Remember: always discuss your results with your doctor or midwife before drawing any conclusions.
Frequently Asked Questions
What is a normal hCG doubling time?
In a healthy early intrauterine pregnancy, hCG typically doubles every 48 to 72 hours when the initial level is below 1,200 mIU/mL. As levels rise between 1,200 and 6,000 mIU/mL, a doubling time of 72 to 96 hours is considered normal. Above 6,000 mIU/mL, even doubling every 96 to 144 hours is within the expected range because the hormone is produced in larger absolute quantities and the rate of rise naturally slows. After hCG peaks between weeks 8 and 11 of pregnancy, it begins to decline, which is completely normal. Importantly, about 15 percent of viable, healthy pregnancies show doubling times outside these typical windows but still result in healthy births. A single doubling time measurement is one clinical data point, not a verdict — always discuss results with your healthcare provider.
What does it mean if my hCG is declining?
A declining hCG level in early pregnancy (before 8 to 10 weeks) can indicate several situations. It may signal a failed intrauterine pregnancy or an early miscarriage that has already begun. It can also indicate an ectopic pregnancy (where the embryo has implanted outside the uterus), which is a medical emergency requiring immediate care. Declining hCG is also completely normal and expected after a miscarriage, after treatment for an ectopic pregnancy, after an hCG trigger shot wears off (in IVF contexts), or after approximately weeks 10 to 12 of an ongoing pregnancy as the placenta matures. If your hCG is declining and you are still in early pregnancy without a confirmed ongoing pregnancy, contact your healthcare provider promptly. Do not wait for a second test on your own.
Can a very high hCG indicate twins?
Very high hCG levels relative to gestational age can be associated with multiple pregnancies (twins, triplets), but hCG alone is not a reliable indicator of multiples. The normal ranges for hCG at any given week are so broad — spanning one to two orders of magnitude — that being in the upper portion of the range does not diagnose twins. Similarly, some singleton pregnancies have hCG levels that are unusually high for their gestational age without any multiple pregnancy being present. A molar pregnancy (a non-viable abnormal placental growth) can also produce very high hCG. The only reliable way to diagnose a multiple pregnancy is via ultrasound. If this calculator flags your level as above the typical range for your week, this is a note to discuss with your clinician, not a definitive twin diagnosis.
How accurate is this hCG doubling time calculator?
The doubling time formula used here — Time × ln(2) ÷ ln(hCG2 ÷ hCG1) — is the standard mathematical formula used in clinical obstetric calculators worldwide, including Perinatology.com, OmniCalculator, MDApp, Femia, and CalculatorPlusTools. The mathematical calculation itself is precise given the inputs. The accuracy of your result, however, depends on the accuracy of your laboratory measurements and how precisely you enter the time between draws. Even a one-hour difference in the elapsed time can shift the doubling time by several hours. For best results, use exact date and time stamps from your lab reports rather than estimating hours. Clinical interpretation thresholds (48-to-72-hour normal range, minimum 49 percent rise per 48 hours) are based on widely published obstetric literature and standard clinical guidelines.
What is the difference between mIU/mL and IU/L?
mIU/mL (milli-international units per milliliter) and IU/L (international units per liter) are mathematically equivalent for hCG — the numerical values are identical. One milli-international unit per milliliter is the same concentration as one international unit per liter. Most US laboratories and online calculators report hCG in mIU/mL. Some European laboratories use IU/L. Since the numbers are the same, you can enter your result in either unit without conversion. This calculator's unit toggle is provided purely for labeling clarity. If you are unsure which unit your lab used, check your laboratory report's reference range — if it lists something like 5–426 for week 4, the values should match the ranges on this page exactly.
Can I use this calculator after an IVF trigger shot?
If you received an hCG trigger shot (such as Pregnyl, Ovidrel, or Novarel) for ovulation induction or IVF preparation, the synthetic hCG from the injection can remain detectable in blood and urine for 7 to 14 days after administration. A positive hCG test within that window may reflect the trigger, not an implanted pregnancy. IVF clinics typically schedule a first pregnancy blood test 9 to 14 days after a 5-day blastocyst embryo transfer to give the trigger time to clear. If you are in an IVF cycle, use the IVF reference table on this page (days post embryo transfer) and follow your clinic's specific testing schedule. A beta hCG above 200 mIU/mL on day 14 post-transfer is generally considered a positive pregnancy test in IVF contexts, with levels above 600 mIU/mL suggesting possible multiples.