HCG level calculator by pregnancy week

What is HCG?

Human Chorionic Gonadotropin, often called beta-HCG, is a hormone your body produces once a fertilised egg implants in the uterine wall. It is made by the cells that later form the placenta. HCG in the blood can often be detected around 11 days after fertilisation, usually earlier than with a urine test. A blood test can show whether HCG is present and at what level, which may give an indication of whether you are pregnant and how far along the pregnancy is.

What hCG level means you are pregnant?

Most laboratories sort a quantitative hCG blood test into three categories. Below 5 mIU/mL is usually read as not pregnant. From 25 mIU/mL upwards is usually read as consistent with pregnancy. Between 5 and 25 mIU/mL the result falls into a middle band often called equivocal or indeterminate, most often simply because it is still early. A repeat measurement 48 to 72 hours later tends to be more informative than the single value.

Laboratories set these cut-offs themselves and do not all use the same ones. Check the reference range printed on your own result, and discuss it with your midwife or GP.

Based on a survey of how laboratories report quantitative hCG results, The Journal of Applied Laboratory Medicine, 2020.

When is hCG detectable after implantation?

Your body only starts producing hCG once the fertilised egg has implanted, usually around 6 to 12 days after ovulation. From that point the level rises quickly. In blood, hCG is often detectable around 11 days after fertilisation, while a urine test usually turns positive a few days later. If you test very early, a low or equivocal result may simply mean it is too soon rather than that something is wrong.

Why the trend matters more than a single hCG level

The range of normal hCG levels for any given week of pregnancy is extremely wide. Around week 5 it runs from 18 to 7,340 mIU/mL, a difference of more than four hundred times. Two women at the same stage can therefore have completely different values with nothing wrong in either case. This is why a single measurement says little, and why midwives and doctors look mainly at how the value develops over a few days.

How fast should hCG rise? On doubling time

You will often read that hCG doubles every 48 to 72 hours in the early weeks. That is the average, not the lower limit, and the difference matters. Research among women later confirmed to have a normally developing pregnancy in the uterus found that the slowest rise in that group was around 53 percent per 48 hours. Later work put the best-performing threshold at around 35 percent per 48 hours, the point at which the fewest pregnancies were misclassified. The rise also flattens as the value climbs: a starting value above 3,000 mIU/mL is expected to rise more slowly than one below 1,500 mIU/mL. A rise that falls short of doubling is therefore not automatically a bad sign.

Your midwife or GP may order hCG twice or more to follow that trend, and will weigh it alongside an ultrasound and your symptoms. Always discuss your own results with them.

Based on Barnhart et al., Obstetrics & Gynecology, 2004 (PMID 15229000) and Morse et al., Fertility and Sterility, 2012 (PMID 22192138).

hCG levels during a miscarriage

During a miscarriage hCG falls, but the pace varies widely from person to person and depends on how high the value was when the decline started. In research, hCG in women having a miscarriage often fell by around 36 to 47 percent per 48 hours, and fell faster the higher the starting value was. There is no single number that applies to everyone. It can also take weeks for the value to drop below the laboratory cut-off, and a pregnancy test may stay positive while hCG is still present in your blood.

A falling hCG level can have several causes and is not a diagnosis in itself. Your midwife, GP or gynaecologist can guide you through this.

What an hCG result can and cannot tell you

An hCG level is a snapshot in time. Whether a value looks low, normal or high depends strongly on how many weeks have passed since fertilisation, and the conception date is often less certain than assumed. This is why a healthcare provider often asks for two measurements around 48 hours apart, so the trend becomes visible. A blood test gives a data point, not a diagnosis. Your GP or midwife can help you understand what your values may mean in your situation.