Why are the hCG ranges so wide?

Because hCG rises so fast in early pregnancy, even being a day or two off on dates moves the expected number a lot — and people simply vary. That's why one hCG value can't reliably date a pregnancy or, on its own, say whether things are healthy. Providers look at the trend across two or more tests, and confirm dating with an ultrasound, rather than reading a single number against an 'average'.

What hCG level shows up on an ultrasound?

A pregnancy sac can sometimes be seen on a transvaginal (internal) ultrasound when hCG is only a few hundred mIU/mL, and it is almost always visible by about 3,500 mIU/mL. Older guides used a cut-off of 1,500–2,000 mIU/mL (the 'discriminatory zone'), but doctors now suggest using a level as high as 3,500 so a wanted pregnancy isn't misjudged. If hCG is above that level but nothing is seen in the uterus, your provider may check for an ectopic pregnancy or an early loss. These thresholds vary by clinic and equipment.

Do higher hCG levels mean twins?

Higher-than-average hCG can be associated with a multiple pregnancy, but it isn't proof of one — plenty of single pregnancies run high, and dating errors explain many 'high' readings. The only reliable way to confirm twins is an ultrasound. So a high number is a maybe, not a yes.

How quickly should hCG rise?

In early pregnancy hCG generally climbs by at least about 35% over 48 hours, and often roughly doubles every 48–72 hours while levels are still low, slowing as levels rise. You can check your own two readings with our hCG calculator, which works out the doubling time and projected 48-hour rise.

hCG Levels by Week

Typical ranges of hCG — the main pregnancy hormone — at each stage, measured in mIU/mL from the first day of your last period. Use them as a rough guide only: the ranges are very wide and overlap, so a healthy pregnancy can sit well outside the “average”.

What is a normal hCG level by week?

Typical ranges (mIU/mL, measured from your last menstrual period) are roughly: 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; then a gradual decline through the second and third trimesters. The ranges are very wide and overlap, so a value far from the 'average' can still be perfectly healthy. Labs also use slightly different reference ranges.

Early rise — in early pregnancy hCG usually climbs by at least about 35% over 48 hours.
Peak — levels peak around 9–12 weeks at 25,700–288,000 mIU/mL, then slowly fall.
Ultrasound — a pregnancy sac often shows on a transvaginal scan once hCG reaches the low thousands, but a normal pregnancy may not show until about 3,500 mIU/mL.
One number is not a diagnosis — providers read the trend across two or more tests, plus an ultrasound.

Have two readings? Check the rise with the free hCG calculator.

Weeks since last period	Typical hCG range (mIU/mL)
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

Ranges are typical published values and vary by laboratory. Always go by your own clinic’s reference ranges and your provider’s reading.

How to read this chart

These numbers are measured in weeks since your last menstrual period (LMP) — the same way pregnancy is usually dated — not weeks since conception. In the first weeks hCG climbs steeply, peaks somewhere around 9–12 weeks, and then settles to a lower, steadier level for the rest of pregnancy. That’s why the ranges rise sharply and then come back down on the chart.

The single most important thing to notice is how wide each range is. At 5 weeks, for example, anything from about 18 to over 7,000 mIU/mL can be normal. A number near the bottom or top of the range is not automatically good or bad news — which is exactly why a single hCG result is rarely read on its own.

The trend matters more than one number

Because the ranges overlap so much, providers care more about how your hCG is changing than about any single value. Two tests a couple of days apart show whether the level is rising as expected — generally by at least about 35% over 48 hours early on, often roughly doubling every 48–72 hours while levels are still low, then slowing as it climbs higher. You can check your own two readings with our hCG calculator, which works out the doubling time and projected rise.

For accurate dating, an early ultrasound (before 14 weeks) beats any hCG number, because it measures the baby’s actual size. To see what’s happening at your stage, pair this with our How Far Along Am I? calculator and week-by-week guide.

When numbers fall outside the range

A value above or below the typical range often has a simple explanation — for example, that the pregnancy is a little further along or less far along than the dates suggest, since being even a day or two out shifts the expected number a lot. Sometimes it reflects a multiple pregnancy (higher) or needs follow-up (a slow rise or fall). None of these can be sorted out from a single number on a chart. If your result is outside the range, the right next step is your provider, who can repeat the test and arrange an ultrasound if needed.

Frequently asked questions

What is a normal hCG level by week?: Typical ranges (mIU/mL, measured from your last menstrual period) are roughly: 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; then a gradual decline through the second and third trimesters. The ranges are very wide and overlap, so a value far from the 'average' can still be perfectly healthy. Labs also use slightly different reference ranges.
Why are the hCG ranges so wide?: Because hCG rises so fast in early pregnancy, even being a day or two off on dates moves the expected number a lot — and people simply vary. That's why one hCG value can't reliably date a pregnancy or, on its own, say whether things are healthy. Providers look at the trend across two or more tests, and confirm dating with an ultrasound, rather than reading a single number against an 'average'.
What hCG level shows up on an ultrasound?: A pregnancy sac can sometimes be seen on a transvaginal (internal) ultrasound when hCG is only a few hundred mIU/mL, and it is almost always visible by about 3,500 mIU/mL. Older guides used a cut-off of 1,500–2,000 mIU/mL (the 'discriminatory zone'), but doctors now suggest using a level as high as 3,500 so a wanted pregnancy isn't misjudged. If hCG is above that level but nothing is seen in the uterus, your provider may check for an ectopic pregnancy or an early loss. These thresholds vary by clinic and equipment.
Do higher hCG levels mean twins?: Higher-than-average hCG can be associated with a multiple pregnancy, but it isn't proof of one — plenty of single pregnancies run high, and dating errors explain many 'high' readings. The only reliable way to confirm twins is an ultrasound. So a high number is a maybe, not a yes.
How quickly should hCG rise?: In early pregnancy hCG generally climbs by at least about 35% over 48 hours, and often roughly doubles every 48–72 hours while levels are still low, slowing as levels rise. You can check your own two readings with our hCG calculator, which works out the doubling time and projected 48-hour rise.

— The Period Tools Team

Sources

Checked against the following public guidance on September 26, 2026. Advice can differ between countries; your doctor, nurse or midwife can apply it to you.