What Is the Normal Size of a Liver in mm?

A normal adult liver measures roughly 140 mm (14 cm) in its longest vertical span when assessed by ultrasound along the midclavicular line, with a typical range of about 100 to 170 mm depending on sex, body size, and how the measurement is taken. That single number, though, hides a lot of variation. The liver is not a neat geometric shape, so its “size” changes depending on which dimension you measure, which imaging technique you use, and even who is holding the probe.

The Standard Adult Measurement

The most commonly quoted figure comes from ultrasound, where a sonographer places the probe along the midclavicular line and measures the liver’s craniocaudal span, essentially from top to bottom. In a study of over 2,000 adults, the average liver span measured this way was 140 ± 17 mm, with men averaging about 145 mm and women about 135 mm.¹ The range in that study ran from 94 mm to 213 mm, which gives you a sense of how much natural variation exists even among people without liver disease.

When measuring specifically the right liver lobe, which is the largest lobe and the one most radiologists focus on, one study found craniocaudal lengths of about 130 ± 15 mm in women and 141 ± 13 mm in men.² The threshold for diagnosing an enlarged liver is usually a right lobe length of 165 mm or more.

Those figures are for a single vertical span. When you look at the liver in three dimensions using CT scanning, the picture gets bigger. A study of healthy adults found the average craniocaudal diameter was 172 ± 20 mm, the front-to-back depth was 158 ± 19 mm, and the side-to-side width was 197 ± 23 mm.³ CT captures more of the organ than a standard ultrasound slice, which is why the numbers run larger. The average total liver volume on CT in that context was about 1,500 cm³.⁴

Why Measurement Technique Matters

If you have ever wondered why different doctors or different reports give you different numbers for the same liver, the answer is usually technique. The liver wraps around the right side of the upper abdomen in a roughly wedge-like shape, and where you place the ultrasound probe and what angle you use directly changes the number you get. A study that tested different ultrasound viewing angles on the same livers found that measurements varied significantly depending on the approach, even though overall reliability within a single technique was good.⁵ A comprehensive review of the field has acknowledged that there is no single globally standardized protocol for measuring liver size on ultrasound, and the interobserver variability between different sonographers remains a recognized limitation.⁶

Physical examination adds another layer of imprecision. When a doctor taps and feels for the edges of your liver at the bedside, they consistently underestimate the organ’s actual size compared to what imaging shows. One prospective study found that the average physical examination estimate was about 89 mm, while the corresponding ultrasound measurement of the same livers averaged 143 mm, giving a correction factor of roughly 1.6.⁷ In other words, the bedside exam picks up only the portion of the liver that extends below the rib cage. Most of the organ sits hidden behind the ribs.

What Pushes Liver Size Up or Down

Several factors influence where your liver falls within the normal range, and most of them are things you would intuitively expect. A multivariate analysis of ultrasonographic liver measurements confirmed that sex, age, body mass index, height, the presence of fatty liver, waist-to-hip ratio, and metabolic syndrome all independently affect liver span.⁸

Sex and body size are the most straightforward: taller, heavier people tend to have larger livers, and men’s livers run about 10 mm longer on average than women’s. This tracks with general allometric scaling, the biological relationship between body mass and organ mass. In humans, the liver scales with body weight at an exponent of roughly 0.7 to 0.9, meaning it grows with body size but not in perfect proportion.⁹ A person who weighs twice as much as another will not have a liver twice the size, but it will be noticeably larger.

Age pulls the liver in the opposite direction. Liver size and blood flow decline in older adults, a change that carries practical consequences for how the body processes medications. Reduced liver volume is considered a key reason why elderly patients metabolize certain drugs more slowly than younger adults.¹⁰ So a 130 mm liver span in a slight, elderly woman may be perfectly normal, while the same measurement in a large young man could be on the small side.

Normal Liver Size in Children

Pediatric liver size is a moving target, changing rapidly with growth. At birth, the liver measures roughly 49 to 55 mm and then increases steadily, reaching up to about 172 mm in adolescents aged 17 to 18.¹¹ That upper adolescent range overlaps with adult values, which makes sense since most teenagers have nearly finished growing.

Height turns out to be a better predictor of liver size in children than age alone. The same study found a more linear relationship between liver size and height than between liver size and age, with reference values extending up to a height of 180 cm where the maximum liver size reached about 175 mm. This is why many pediatric radiology departments use height-based reference charts rather than age-based ones.

Ethnicity and generation also play a role. A Central European study of over 700 children found that from the second year of life onward, the craniocaudal right-lobe dimension was 10 to 20 mm larger than values reported in non-Caucasian populations at the same age. Even within the same Central European population, children measured in 2020 had larger livers than a comparable group measured almost four decades earlier, likely reflecting secular trends in nutrition and body size. Boys had statistically larger livers than girls at every age.¹²

Detecting an enlarged liver in a child is trickier than in an adult, since the normal range shifts so quickly with growth. One approach uses the subcostal diameter, measuring how far the liver edge extends below the rib margin. A study comparing children with known hepatomegaly to healthy controls found that a subcostal diameter cutoff of about 20 mm worked well for identifying enlargement across a broad age range, without needing age-specific adjustments.¹³

Fatty Liver and Enlargement

Fatty liver disease is the most common reason a liver outgrows its normal dimensions without the person necessarily feeling anything wrong. A study comparing patients with non-alcoholic fatty liver disease to healthy controls found a mean liver span of about 149 mm in the fatty liver group versus 135 mm in controls, a gap of roughly 15 mm.¹⁴ The enlargement tracked with disease severity: people with mild fat accumulation averaged about 144 mm, those with moderate disease about 154 mm, and those with severe steatosis about 159 mm.

This is worth knowing because many people discover they have a “large liver” incidentally during an ultrasound for something else. If you are told your liver measures, say, 160 mm and you have a higher BMI, fatty liver is the likely explanation well before anyone should worry about more ominous causes. The same study confirmed that age, sex, height, BMI, and the degree of fat accumulation were all independent predictors of liver size, reinforcing that a single cutoff for “too big” oversimplifies things.

Cirrhosis and a Shrinking Liver

While fatty liver makes the organ swell, advanced cirrhosis often does the opposite, at least in specific regions. The scarring process does not shrink the liver uniformly. Instead, it creates a distinctive pattern: the right lobe and certain central segments tend to shrink while the left lateral segment and the caudate lobe enlarge to compensate. A study examining morphometric changes across different causes of cirrhosis found that this pattern of right-lobe atrophy combined with caudate and lateral segment hypertrophy was consistent regardless of whether the cirrhosis was caused by alcohol, hepatitis, or other conditions.¹⁵

This uneven reshaping is important because a simple overall liver length measurement can look normal or even slightly enlarged in early cirrhosis, even though the internal architecture is already distorted. Radiologists look for specific changes in the proportions between lobes rather than relying solely on the overall span. A liver that measures 140 mm overall but has a shrunken right lobe and a ballooned caudate lobe tells a very different story than one with normal proportions across the same total span.

Pregnancy and Temporary Liver Growth

One of the more surprising findings in liver research is that the organ grows substantially during pregnancy. An MRI-based study found that liver volume increased an average of about 15% from early to late pregnancy, going from roughly 1,239 cm³ to 1,421 cm³.¹⁶ That amounts to an increase of about 182 cm³, which is a meaningful chunk of tissue. The researchers noted that this growth did not simply track with overall body weight gain during pregnancy, suggesting it is driven by a separate biological program linked to the reproductive state rather than the body’s general “thermostat” for maintaining liver size.

Animal research supports this picture. In mice, the maternal liver roughly doubles in weight by late pregnancy, a change confirmed to be genuine tissue growth involving both cell enlargement and cell division rather than just fluid retention.¹⁷ This may partly explain why standard liver reference ranges can flag a pregnant woman as having an enlarged liver when the enlargement is actually physiological and expected. If you are pregnant and an ultrasound report mentions a liver span at the upper end of normal, the finding is usually not alarming in that context.

How Eating Affects the Numbers

A question that comes up surprisingly often in radiology is whether you need to fast before a liver size measurement. The liver is a metabolically active organ that processes nutrients from every meal, so it would be reasonable to expect it to swell after eating. A study using single-photon emission CT to track liver volume before and after meals found that food intake had only a marginal effect on liver and spleen volume, and the changes fell within the normal error range of the imaging technique itself.¹⁸ In practical terms, whether you ate lunch before your ultrasound is unlikely to change a liver measurement enough to push it across any clinical threshold.

The Liver’s Ability to Regrow

One reason surgeons can remove large portions of a diseased liver is the organ’s remarkable regenerative capacity. After a major liver resection, where more than half the organ may be removed, functional recovery happens faster than structural recovery. One study showed that liver function bounced back to about 77% of its preoperative level within just 10 days, with full functional restoration achieved by about 12 weeks. However, the liver’s physical volume at that same 12-week mark was still only about 73% of its original size.¹⁹

A separate study looking at liver regrowth three months after major resection found that the remnant typically regenerated to about 80% of the original total liver volume and recovered over 83% of its original function.²⁰ The liver does not regrow to its exact former shape or size. Instead, the remaining tissue enlarges to fill the functional gap, a process closer to compensatory growth than true regeneration in the sense a salamander regrows a limb. For anyone facing liver surgery, the takeaway is that the organ is designed to recover from substantial loss, but a post-surgical liver that measures smaller than textbook “normal” is not necessarily a sign of a problem.

Putting the Numbers in Context

If you have come across a liver measurement on a radiology report and are trying to figure out whether it is normal, the most useful reference point is the midclavicular craniocaudal span on ultrasound. For an average-sized adult, roughly 120 to 160 mm covers the normal range, with 140 mm as a reasonable midpoint. Men and taller individuals land toward the higher end; women and smaller individuals toward the lower end. A right-lobe measurement above about 165 mm is the conventional threshold where radiologists start considering hepatomegaly, but that cutoff is a guideline rather than a bright line, especially if the person is tall, has a high BMI, or is pregnant.

CT-based dimensions are inherently larger because the scan captures the full three-dimensional extent of the organ, including the widest points that ultrasound may miss. If a CT report gives you a craniocaudal diameter of 170 mm, that does not mean the same thing as an ultrasound reading of 170 mm. The two measurements are not interchangeable without understanding which technique produced them. Whenever possible, compare your number against reference ranges specific to the imaging method that was used. And if you are tracking liver size over time, consistency in technique matters more than the absolute number on any single scan.