hCG levels by week calculator
Enter an hCG result and the week of pregnancy to see it against a named laboratory's published reference range. The ranges are enormous and overlap heavily between weeks, so the tool leads with what a single number cannot tell you, and what clinicians read instead.
hCG levels by week calculator
No sign-up · PrivateIn mIU/mL, as printed on your report. This tool compares it with one named laboratory’s published ranges — not with your own laboratory’s, which are the ones that apply to you.
Optional. The list of overlapping weeks does not depend on it — it is only used to show you the range for the week you are in.
Published weeks whose range contains 20,000 mIU/mL
That list is the point of this tool, not a failure of it. Your value is consistent with all of those weeks at once, so it cannot tell you which one you are in.
Against week 6: 20,000 mIU/mL is inside the published range for week 6 (158 to 31,795 mIU/mL). That is a comparison with one laboratory’s reference interval. It is not a result, a diagnosis or a prediction, and a single draw is not how any of those are made.
The width of that one week: Week 6 spans 158 to 31,795 mIU/mL — a 201-fold spread within a single week, in healthy pregnancies.
Weeks that overlap with your value: 7 of the 14 published weeks contain 20,000 mIU/mL: weeks 6, 7, 14, 15, 16, 17 and 18. This is why a single value cannot date a pregnancy.
Reference range source: Labcorp test 004416, hCG beta subunit, quantitative, serum, in mIU/mL, by completed week from the start of the last menstrual period.
Nothing you type leaves your device. The whole calculation runs in your browser.
How this is calculated
FormulaHow this comparison works, and its limits
Read this part before the number. A single hCG result is one of the most over-interpreted figures in early pregnancy, and the shape of the published data explains why.
What a single hCG value cannot do
- It cannot date a pregnancy. The published ranges for adjacent weeks overlap so heavily that one value is consistent with several different weeks at once.
- It cannot predict the outcome. Values inside the range occur in pregnancies that do not continue, and values outside it occur in pregnancies that do.
- It cannot locate the pregnancy. Only a scan can show where a pregnancy is.
What clinicians read is the trend across two or more draws taken 48 hours apart, interpreted alongside a scan and your symptoms. That is a different calculation, and this site has a separate tool for it.
Step 1 — the reference range used
The ranges below are the published reference values for Labcorp test 004416, hCG beta-subunit, quantitative, serum, reported in mIU/mL. Weeks are counted as completed weeks beginning with the start of the last menstrual period, which is the same convention used for dating a pregnancy.
They are one laboratory's values for one assay. This matters more than it sounds: hCG assays differ, and a result from a different laboratory is not always directly comparable with these numbers. Your own laboratory prints its own reference range on the report, and that is the one that applies to your result. Use these to understand the shape of the data, not to overrule your own report.
Step 2 — the published values
In mIU/mL, by completed week of gestation: 3: 6–71, 4: 10–750, 5: 217–7,138, 6: 158–31,795, 7: 3,697–163,563, 8: 32,065–149,571, 9: 63,803–151,410, 10: 46,509–186,977, 12: 27,832–210,612, 14: 13,950–62,530, 15: 12,039–70,971, 16: 9,040–56,451, 17: 8,175–55,868, 18: 8,099–58,176. For reference, the same laboratory gives 0–5 for a non-pregnant female and 0–8 post-menopause.
Weeks 11 and 13 are not published in this table and the tool does not invent them. Where a week has no published range, it says so rather than interpolating, because interpolating across ranges this wide would manufacture a precision that is not there.
Step 3 — what the tool shows you
It places your value against the range for the week you entered, and then does the thing most calculators skip: it shows you every other week whose published range also contains your value. For most results in early pregnancy that list has several entries. That display is the point of the tool.
Look at week 6 in particular: 158 to 31,795. The lower bound is below week 5's lower bound of 217, and the upper bound overlaps weeks 7 through 12. The ranges are not even monotonic. Any tool that reads a week off a single value is reading noise.
Step 4 — the situations that shift things
Twins and higher multiples tend to run higher, but the ranges overlap singleton ranges so much that hCG is not used to diagnose twins. After IVF, count from the transfer date and embryo age as your clinic instructs rather than from a last period. Levels peak somewhere around weeks 8 to 11 and then fall for the rest of the pregnancy, so a falling result later on is expected rather than alarming.
What does my hCG level mean?
If you are reading this, you are probably holding a number and trying to make it say something. It is worth being direct about what it can say, because the gap between what people hope a single hCG result tells them and what it actually tells them causes an enormous amount of avoidable fear.
Human chorionic gonadotropin is produced in pregnancy and rises steeply in the early weeks. In the first eight weeks it roughly doubles about every 24 to 48 hours, peaks somewhere in the region of weeks 8 to 11, and then declines for the remainder of the pregnancy. That is the pattern. The trouble is that the normal range around that pattern is vast.
The ranges overlap so much they cannot date a pregnancy
Look at what one named laboratory publishes. At 6 weeks the reference range runs from 158 to 31,795 mIU/mL. That is a two-hundred-fold spread within a single week, in healthy pregnancies. At 7 weeks it runs from 3,697 to 163,563. A result of 20,000 sits inside the published range for week 6, week 7, week 14, week 15, week 16, week 17 and week 18 simultaneously — early pregnancy and mid pregnancy at once, with weeks 8 to 12 ruled out because their published floors all sit above it.
Stranger still, the ranges are not even in ascending order. Week 6's floor of 158 is lower than week 5's floor of 217. This is not a misprint; it is what happens when you take the observed spread of a rapidly changing hormone across a lot of people and cut it into weekly slices. It means that a calculator claiming to tell you how many weeks pregnant you are from an hCG value is doing something the underlying data cannot support.
So what is the number for?
Clinically, a single hCG measurement is rarely the point. It is a baseline. What gets interpreted is the change between two measurements taken about 48 hours apart, read together with an ultrasound scan and how you are feeling. A rise that is slower than expected, a plateau, or a fall can prompt further investigation — but each of those can also occur in pregnancies that continue perfectly well, which is why no clinician makes a decision on one draw.
Where a single value genuinely does matter
There is one context in which the absolute number carries weight, and it is worth knowing about. In early pregnancy of uncertain location, the level is used alongside scanning to decide what happens next, because an ectopic pregnancy classically shows a slower rate of rise without the expected doubling. This is a decision made by a clinician with a scanner, not by a chart.
If you have pain on one side of your tummy, shoulder-tip pain, bleeding, pain when passing urine or opening your bowels, or you feel faint or dizzy, do not wait to compare numbers. Ectopic pregnancy is a medical emergency and needs assessment now. Contact your early pregnancy unit, your GP or 111, and in an emergency call 999.
Why your laboratory's range may differ from this one
hCG assays are not standardised across laboratories in the way you might assume. Different platforms detect somewhat different mixtures of the intact hormone and its fragments, and their reference intervals differ accordingly. The ranges on this page are Labcorp's published values for one specific test, and they are used here because they are published openly with the week-by-week breakdown intact.
Your report will carry its own reference range. If they disagree, yours is the one that applies. Comparing a result from one laboratory against another's range, or comparing your result this week with a friend's result at the same week, is not a like-for-like comparison.
Twins, IVF and home tests
Pregnancies with twins tend to produce higher levels, but the overlap with singleton ranges is so large that hCG is not used to diagnose a multiple pregnancy. A scan does that. After IVF, dating runs from the transfer and the age of the embryo transferred, so a level should be interpreted against the clinic's own schedule.
Home pregnancy tests measure the same hormone in urine, typically detecting from somewhere around 20 to 50 mIU/mL. That is why a test can be negative one day and positive two days later in the same pregnancy. The darkness of a line is not a measurement, and comparing line darkness between different brands, or between tests taken at different times of day with differently dilute urine, tells you very little.
What a falling level means, and when it does not
Later in pregnancy a falling result is simply expected. After the peak somewhere around weeks 8 to 11, levels decline for the rest of the pregnancy, so a lower number at 16 weeks than at 10 weeks is the normal pattern rather than a warning sign. People who have had levels monitored early sometimes keep checking out of habit and frighten themselves with an entirely ordinary decline.
In the first weeks, a fall does carry information, but still not on its own. It is read alongside a scan, any bleeding or pain, and how far along you are, and it is one of the findings that prompts closer follow-up rather than a conclusion in itself. Whatever the trend, if you have bleeding or pain in early pregnancy, contact your early pregnancy unit or GP rather than waiting for a repeat blood test.
The honest summary
A single hCG value places you inside a very wide band that overlaps several weeks. It cannot date your pregnancy, it cannot tell you where the pregnancy is, and it cannot tell you whether it will continue. Those things come from a scan, from the trend across repeated draws, and from clinical assessment.
If you are frightened by a number you have been given, the most useful thing is not another calculator. It is to ask the team who took the blood what they are watching for and when they want to repeat it. That answer will tell you more than any range on any website.
Sources
- Human Chorionic Gonadotropin (hCG), beta-Subunit, Quantitative, test 004416, reference ranges by week of gestation — Labcorp, accessed
- Human Chorionic Gonadotropin — StatPearls, NCBI Bookshelf, accessed
- Ectopic pregnancy — NHS, accessed
- Ectopic pregnancy and miscarriage: diagnosis and initial management (NG126) — NICE, accessed
- Miscarriage — NHS, accessed