hCG levels: why one result cannot be judged alone
hCG levels are the amount of human chorionic gonadotropin, the pregnancy hormone, in blood or urine, and a single result cannot be judged without the stage of pregnancy, the laboratory and a clinician. This guide explains what hCG is, when it appears, why published ranges are wide and why no calculator on this site tells you whether a level is right.
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Medically reviewed by Dr Mary Davidson, Reproductive endocrinologist, checked on
Seek help now if you have any of these symptoms
Bleeding and cramping are common in early pregnancy and often do not mean miscarriage. The symptoms below, however, need to be assessed straight away.
- Soaking two or more sanitary pads per hour, or passing large clots
- Severe lower abdominal pain, especially on one side
- Pain at the tip of the shoulder
- Dizziness, fainting, or collapse
- Signs of shock — pale, clammy, rapid heartbeat, breathlessness
- Pain on opening bowels, or bladder or bowel changes
- Feeling very unwell, or feverish
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A pregnancy hormone result, high or low, does not replace urgent care for symptoms. The NHS treats bleeding in pregnancy as an emergency when it comes with severe abdominal pain, pain in the shoulder, or feeling sick, faint or dizzy, and when it is heavy enough to soak a period pad soon after you put it on (NHS, 2026). In the UK, call the emergency number or go to A&E, the hospital emergency department; in the US, call the emergency number or go to the nearest emergency room. The box above shows the emergency and urgent numbers for where you are, and get help now lists the other symptoms that need checking straight away.
hCG is the hormone every pregnancy test looks for
MedlinePlus, from the US National Library of Medicine, explains that human chorionic gonadotropin (hCG) is made by the placenta, which starts making it after a fertilized egg attaches to the inside wall of the uterus, and that levels then continue to rise for ten weeks (MedlinePlus, "Pregnancy Test", 2026). The NHS says all pregnancy tests detect it and that it starts to be produced around 6 days after fertilization (NHS, "Doing a pregnancy test", 2022). The FDA says it appears shortly after the embryo attaches to the wall of the uterus (FDA, "Pregnancy" home use tests, 2019).
In a study of 221 women trying to conceive, Wilcox, Baird and Weinberg took implantation to be the first appearance of hCG in urine. In the 141 pregnancies that lasted at least six weeks, it appeared 6 to 12 days after ovulation, and in 84 in 100 of them on day 8, 9 or 10 (New England Journal of Medicine, 1999). For a 28-day cycle, the FDA says hCG can be detected in urine 12 to 15 days after ovulation (FDA, 2019). When does implantation occur sets out that timing.
Urine tests show whether hCG is present, blood tests can show how much
The FDA describes a home test as qualitative: you find out whether hCG is raised, not how much (FDA, 2019). That is also why a faint positive pregnancy test cannot show a level. MedlinePlus describes two kinds of blood test: a qualitative test that shows whether hCG is present, and a quantitative test, also called beta hCG, that measures the exact amount in milli-international units per milliliter (mIU/mL). Quantitative tests are sometimes used to find the age of the fetus very early in pregnancy, to monitor a pregnancy at high risk of miscarriage, and to check for an ectopic or a molar pregnancy (MedlinePlus, 2026). The Office on Women's Health says a quantitative blood test can also tell you and your doctor how many weeks pregnant you are (Office on Women's Health, 2025).
Published ranges are very wide
The MedlinePlus encyclopedia entry for the quantitative test gives expected ranges by week of pregnancy. It states that levels below 5 mIU/mL are normal in a woman who is not pregnant, and it gives these ranges for early pregnancy (MedlinePlus, "HCG blood test - quantitative", 2024):
| Week of pregnancy | Range given by MedlinePlus (mIU/mL) |
|---|---|
| 4 weeks | 10 to 708 |
| 5 weeks | 217 to 8,245 |
| 6 weeks | 152 to 32,177 |
The same entry says that normal values may vary slightly among laboratories and advises talking to your health care provider about the meaning of your specific test result. The table is here to show the width of the ranges, not to compare a result against. The ranges overlap from one week to the next, and a person's week of pregnancy is itself an estimate (see estimated gestational age).
Sources differ on how fast hCG rises
MedlinePlus says levels keep rising for ten weeks, almost doubling every three days (MedlinePlus, "Pregnancy Test", 2026). The Office on Women's Health says that if you are pregnant your hCG levels should double every 48 hours (Office on Women's Health, "Pregnancy tests", 2025). The two statements do not agree, and neither is a target for one person's results. The NHS explains that hCG blood tests may be done twice, 48 hours apart, to see how the level changes over time (NHS, "Ectopic pregnancy: diagnosis", 2022). A clinician reads the pattern alongside a scan and symptoms.
Why this site has no hCG calculator
People search for an hCG calculator or an hCG doubling calculator, and this site does not offer one. The ranges above are too wide for a single result to be placed on them, the published doubling times differ, and MedlinePlus advises taking the meaning of a specific result to your provider. What the site does offer is dating: the due date calculator and the pregnancy week calculator work from dates, and how soon can you take a pregnancy test covers when a home test can show a result.
hCG can be raised for reasons other than pregnancy
MedlinePlus says fertility medicine could affect a pregnancy test result and that a provider may need to verify a positive test taken during fertility treatment (MedlinePlus, 2026). After an IVF transfer, the clinic sets the test date; the guide to embryo transfer explains when it usually falls. Its encyclopedia entry also lists conditions unrelated to pregnancy that can raise hCG, and it advises talking to your provider about a specific result (MedlinePlus, 2024).
When to get help
A hormone result is not a reason to wait if you have symptoms. Bleeding or pain in early pregnancy needs a decision about where to get advice, and implantation bleeding explains the routes in the UK and the US. The get help now page lists the symptoms that need checking straight away.
This guide is information, not a diagnosis or a recommendation of treatment, and it is no substitute for your own clinician. See the medical disclaimer.
Sources
- National Library of Medicine, MedlinePlus. Pregnancy Test. MedlinePlus, 2026.
- National Library of Medicine, MedlinePlus. HCG blood test - quantitative. MedlinePlus Medical Encyclopedia, 2024.
- NHS. Doing a pregnancy test. nhs.uk, 2022.
- US Food and Drug Administration. Pregnancy (home use tests). FDA, 2019.
- Office on Women's Health, US Department of Health and Human Services. Pregnancy tests. womenshealth.gov, 2025.
- Wilcox AJ, Baird DD, Weinberg CR. Time of implantation of the conceptus and loss of pregnancy. New England Journal of Medicine 340(23): 1796-1799, 1999.
- NHS. Ectopic pregnancy: diagnosis. nhs.uk, 2022.
- NHS. Vaginal bleeding in pregnancy. nhs.uk, 2026.
Frequently asked questions
What is hCG?
Human chorionic gonadotropin is a hormone made by the placenta after a fertilized egg attaches to the wall of the uterus (MedlinePlus, 2026). All pregnancy tests detect it (NHS, 2022).
When can hCG be detected?
The NHS says hCG starts to be produced around 6 days after fertilization (NHS, 2022). In a study of 221 women, it first appeared in urine 6 to 12 days after ovulation in pregnancies that lasted at least six weeks (Wilcox et al., 1999). For a 28-day cycle the FDA says it can be detected in urine 12 to 15 days after ovulation (FDA, 2019).
What is a normal hCG level?
There is no single figure. MedlinePlus lists ranges that are very wide, for example 10 to 708 mIU/mL at 4 weeks and 217 to 8,245 at 5 weeks, and says ranges vary between laboratories and that the meaning of a specific result is a question for your provider (MedlinePlus, 2024).
Do hCG levels double every 48 hours?
Sources differ. The Office on Women's Health says levels should double every 48 hours (2025), while MedlinePlus says levels almost double every three days for the first ten weeks (2026). Neither is a pass mark for one person's result.
Can a home test show my hCG level?
No. The FDA describes a home test as qualitative: it shows whether hCG is raised, not how much there is (FDA, 2019). A quantitative blood test measures the amount (MedlinePlus, 2026).
Why are blood tests sometimes repeated 48 hours later?
The NHS says hCG blood tests may be done twice, 48 hours apart, to see how the level changes over time (NHS, 2022). One result alone shows less than two.