A healthy adult spleen is roughly the size of a clenched fist, measuring about 9 to 10 cm long (3.5 to 4 inches). It weighs around 150 to 200 grams, or about as much as a small apple. But “normal” varies quite a bit depending on your sex, height, age, and body weight.
Normal Spleen Size in Adults
The most common way to measure a spleen is by its longest dimension, taken on ultrasound from the bottom tip up to where it meets the diaphragm. In a study of over 1,000 healthy adults, the median spleen length for men was 9.6 cm, with a normal range of 7.8 to 11.7 cm. For women, the median was 8.7 cm, ranging from 7.2 to 10.5 cm. Width typically runs about 7 cm and thickness about 3 to 4 cm, though length is the measurement doctors rely on most.
The spleen sits tucked behind your 9th through 11th ribs on the left side, between the top of your stomach and the diaphragm. Because it’s shielded by the ribcage, a normal spleen can’t be felt during a physical exam. If a doctor can feel the edge of your spleen below your ribs, it’s already significantly enlarged.
What Affects Your Spleen Size
Three factors have the strongest influence on how big your spleen should be: sex, body mass index, and age.
- Sex: Men’s spleens run nearly a full centimeter longer than women’s on average, even after adjusting for height and weight.
- Height and BMI: Taller and heavier people have larger spleens. Women in the 140 to 149 cm height range had a median spleen length of 8.3 cm, while women 170 to 179 cm tall averaged 9.5 cm. In men, those with a BMI over 30 had a median spleen length of 10.5 cm, compared to 9.0 cm for men with a BMI under 20.
- Age: The spleen gradually shrinks as you get older. For every decade of life, spleen length drops by roughly 2 to 3 millimeters.
This variability matters because a 12 cm spleen in a tall man may be perfectly normal, while the same measurement in a petite older woman could signal a problem.
Normal Spleen Size in Children
Children’s spleens grow steadily from infancy through adolescence. Pediatric radiologists use age-based upper limits measured on ultrasound:
- Newborn to 3 months: up to 6 cm
- 6 to 12 months: up to 7 cm
- 1 to 2 years: up to 8 cm
- 2 to 4 years: up to 9 cm
- 4 to 6 years: up to 9.5 cm
- 6 to 8 years: up to 10 cm
- 8 to 10 years: up to 11 cm
- 10 to 12 years: up to 11.5 cm
- 12 to 15 years: up to 12 cm
- 15 to 20 years: up to 12 cm for females, up to 13 cm for males
By the late teen years, the spleen is essentially adult-sized. The sex-based difference starts appearing around age 15, with boys’ spleens continuing to grow about a centimeter longer than girls’.
When a Spleen Is Considered Enlarged
The traditional cutoff for an enlarged spleen (splenomegaly) is 12 cm in length. In practice, this number isn’t absolute. Lengths up to 14 cm can be normal in taller men. On CT scans, doctors also look at width: anything over 10.6 cm in the widest dimension raises concern.
Enlargement is typically graded by severity. Moderate splenomegaly means the longest dimension falls between 11 and 20 cm. Severe or “massive” splenomegaly means the spleen exceeds 20 cm, roughly double its normal length. In weight terms, a spleen over 400 to 500 grams is considered enlarged, while one exceeding 1,000 grams (over 2 pounds) qualifies as massively enlarged. At that size, the spleen can extend across the midline of the abdomen and down toward the pelvis.
Common causes of an enlarged spleen include infections (especially mononucleosis), liver disease with portal hypertension, blood cancers like lymphoma, and certain autoimmune conditions. The spleen enlarges because it’s working harder to filter abnormal blood cells, or because blood is backing up into it from increased pressure in the portal vein.
How Spleen Size Is Measured
Ultrasound is the standard tool for measuring spleen size. It’s quick, painless, and doesn’t involve radiation. The technician places the probe along your left side between the ribs and measures the longest distance from the spleen’s bottom tip to its highest point against the diaphragm, crossing through the central area where blood vessels enter (the hilum). This single measurement, the craniocaudal length, is the number that appears on most imaging reports.
CT scans provide a more detailed picture and are often used when ultrasound findings are unclear or when doctors need to evaluate the spleen’s internal structure. On CT, both the length and width are measured, and the spleen’s volume can be calculated more precisely. If you’re reading an imaging report, the key number to look at is the longest dimension in centimeters, and how it compares to the 12 cm general threshold, adjusted for your body size.