Beta hCG doubling time calculator and charts

Human chorionic gonadotropin, or hCG, is the hormone your body produces when you are pregnant. In fact, hCG showing up in your blood or urine is one of the earliest signs of pregnancy, which is why lots of people are eager to know more about normal hCG levels.

Get started with our hCG calculator now (above) to work out your hCG levels at home by entering the results of two blood tests and the time between those tests. Then scroll down for everything you need to know about hCG levels in early pregnancy. 

Remember that hCG calculator tools and hCG level charts can help you learn more about the part hCG plays in pregnancy. But they are for informational purposes only, not a replacement for medical advice nor a self-diagnosis tool. Your doctor should always be your first port of call when it comes to tracking and explaining hCG progression.

When does hCG start?

First up, you might be wondering when hCG starts to show up. The pregnancy hormone can be picked up in your urine and your blood once the embryo attaches itself to the uterine wall (between days 6 and 14 after the sperm has fertilized the egg).

A positive test confirms you’re pregnant. At-home pregnancy tests work by detecting hCG in your pee — normally from days 5 to 10 after your expected period, but some sensitive tests can detect it as early as 10 days after conception. 

Dr. Sara Matthews, consultant gynecologist and fertility specialist at London’s Portland Hospital, says, “Home pregnancy tests using urine are very accurate. A positive result pretty much means you are pregnant, but before you celebrate or panic, make sure you are reading the test correctly — always check the instructions! A negative result may mean it’s simply too early to test, so if a period is delayed, the test should be repeated 2 to 3 days later.”

Your doctor can request an in-clinic blood test to check for hCG. “This can be useful if there has been bleeding and a miscarriage is possible,” Dr. Matthews explains. “It can also help the doctor if an ectopic pregnancy is suspected (a pregnancy that has implanted outside the womb).” 

Beta hCG calculator: What does hCG show?

We now know that hCG in your urine and blood can show you’re pregnant, but that’s not all. Your health care provider can also learn more about how your pregnancy might be progressing from the hCG levels in your blood. 

“A pregnancy cannot be detected reliably by ultrasound until six weeks of pregnancy, so sometimes blood levels are monitored before then,” explains Dr. Matthews.

Beta hCG calculator: What if hCG levels are low?

Let’s look at what different hCG levels can mean with a little help from Dr. Matthews: 

• Higher than average hCG levels might indicate that you’re having twins or triplets, but you’ll need an ultrasound scan to confirm this. “A normal blood level for hCG on the day a period is due (14 days after ovulation) is 40 to 120 mIU/mL, but levels are up to 400 in multiple pregnancies!” she says. Higher than average hCG levels could also suggest your due date is wrong (you’re further along in your pregnancy than you thought!). Sadly, they can also indicate a molar pregnancy (when the placenta grows abnormally). “[Molar] pregnancy always ends in miscarriage, and careful monitoring of the hCG levels may be required for up to six months,” says Dr. Matthews.
• Falling hCG levels within the first six weeks could mean you’re at higher risk of having a miscarriage. If you’re worried about your hCG levels, then speak to your doctor right away.
• Lower than average hCG levels “might indicate that the pregnancy implanted a day or two later than expected,” Dr. Matthews says. It could also mean an ectopic pregnancy or a “biochemical” pregnancy. A biochemical pregnancy is a very early miscarriage where the embryo implants, but only for a few days, and a late period happens before a scan to confirm a pregnancy can be done. Again, speak to your doctor if you think this might apply to you.

It’s important to remember that hCG levels are not a diagnosis on their own. They are just a sign that your doctor might need to do more tests. The tool above is designed for informational purposes only; you should always reach out to your health care provider for early pregnancy advice and support.

hCG progression: What is a normal hCG level in pregnancy? When do hCG levels stop doubling?

hCG levels in our blood change during the first trimester, rising rapidly. 

Nonpregnant women have less than 5 milli-international units per milliliter (mIU/mL). “A normal blood level for hCG on the day a period is due (14 days after ovulation) is 40 to 120 mIU/mL,” Dr. Matthews says. 

Levels should then double every 48 hours from weeks four to six, but that isn’t the case for everyone. hCG can vary from person to person and still mean a pregnancy is normal. In fact, a 2017 study into hCG found that “the slowest or minimal rise for a normal viable intrauterine pregnancy was 24% at one day and 53% at two days. More recently, a rise of 35% over 48 hours was proposed as the minimal increase consistent with a viable intrauterine pregnancy.” 

Dr. Matthews adds that “hCG levels peak at around eight [to ten] weeks of pregnancy. [They] are unreliable after that, but at that stage, ultrasound is used [anyway].”

hCG levels in early pregnancy

Remember that hCG levels vary from person to person and can be lower than average, so the above beta hCG chart should only be used as a rough guide.

hCG doubling time: What does it mean?

It’s important not to get fixated on hCG doubling time because, as we’ve learned, every pregnancy is different. That means your hCG levels might not double but are totally normal for you. 

That said, it’s useful to know how hCG doubling time works in theory. Over to Dr. Matthews again: “An hCG level should double every 48 hours from four to six weeks [of pregnancy]. A level that does not double should be rechecked after another two days as it might indicate a failing pregnancy or a PUO (pregnancy of unknown origin). 

“But an initially high level can also fall in a multiple pregnancy when one baby stops growing. In this situation, the other baby is not affected by that unless twins or triplets are identical (they come from one embryo that split when it’s implanted).”

Speak to your doctor to put your hCG levels into context.

At what hCG level will I miscarry?

“A miscarriage is likely if the hCG level falls in the first six weeks of pregnancy, but don’t forget that it can also fall from a high level with an early ‘vanishing twin,’ so if no bleeding has happened by six weeks, then always scan to find more information,” Dr. Matthews says. 

“That is also of course an essential way to diagnose an ectopic pregnancy, commonly called a PUO (pregnancy of unknown origin), in the early stages that might be resolving itself without the need for an operation.

“A negative urine hCG pregnancy test is registered when the level of hormone drops below 4 mIU/mL [or the test sensitivity threshold]. A period will inevitably start within 1 to 2 days.”

How Flo can help

In the early stages of pregnancy? We’ve got plenty of personalized information to help you track your baby’s development and changes to your body, week by week. Download the app now to get started.