The human body contains about 78 organs, each with its own essential function. The largest organs by weight are a mix of well-known internal organs and the skin, which is the body's largest organ by both weight and surface area. Together, the top ten organs account for roughly 9 to 10 kg of an average adult's body weight — about 12 to 15 percent of total body mass.
This list ranks the ten largest human organs by average weight in a healthy adult, drawing on medical reference data. Weights vary significantly between individuals based on height, body composition, age, and sex. The figures shown are population averages for an adult male; female averages are typically 10–20% lower for most organs.
Ad · leaderboard
Average weight (g)
Average weight (g)
Skin
4535 g
Liver
1560 g
Brain
1500 g
Lungs (pair)
1300 g
Heart
300 g
Kidneys (pair)
260 g
Spleen
175 g
Pancreas
70 g
Thyroid gland
20 g
Prostate gland
11 g
The ranking
1
Skin
The skin is the body's largest organ by both weight and surface area. It covers about 1.5 to 2 square meters in an average adult and serves as the first line of defense against pathogens, UV radiation, and physical injury. The skin also regulates body temperature through sweating and blood flow, synthesizes vitamin D, and houses sensory receptors for touch, pressure, pain, and temperature. The weight figure here includes the epidermis and dermis only.
System: IntegumentaryFunction: Protection, temperature regulation, sensation, vitamin D synthesisLocation: Entire body surfaceNote: Epidermis + dermis only (subcutaneous fat excluded)
2
Liver
The largest internal organ and the largest gland in the body. The liver performs over 500 essential functions, including detoxifying blood, producing bile for fat digestion, storing glycogen and vitamins, and synthesizing blood plasma proteins. Its remarkable regenerative capacity — it can regrow to full size after a 70% resection — is unique among internal organs.
System: DigestiveFunction: Detoxification, bile production, metabolism, glycogen storageLocation: Right upper abdomenNote: Largest internal organ
3
Brain
The command center of the nervous system, the brain weighs about 1.5 kg and contains roughly 86 billion neurons. Despite making up only about 2% of body weight, the brain consumes approximately 20% of the body's oxygen and energy. The brain's weight decreases slightly with age, losing about 5–10% of its mass between ages 30 and 80.
System: NervousFunction: Cognition, coordination, sensory processing, motor controlLocation: Cranial cavity (skull)Note: ~86 billion neurons; ~20% of body's energy use
Ad · in-feed
4
Lungs (pair)
The two lungs are the primary organs of the respiratory system. The right lung is slightly larger and heavier than the left (which accommodates the heart). Together, the pair weighs about 1.3 kg. The lungs contain roughly 300 to 500 million alveoli, providing a total surface area of about 70 to 100 square meters for gas exchange — roughly the size of a tennis court.
System: RespiratoryFunction: Gas exchange (oxygen in, carbon dioxide out)Location: Thoracic cavity (chest)Note: Combined weight of both lungs; right lung is heavier
5
Heart
The heart is a muscular pump that beats about 100,000 times per day, moving approximately 7,500 liters of blood through the circulatory system. It weighs about 300 grams and is roughly the size of a fist. The heart's weight can increase with exercise (athlete's heart) or with conditions such as hypertension, which can double the size over time.
System: CardiovascularFunction: Pumps blood through circulatory systemLocation: Mediastinum (center of chest, between lungs)Note: ~100,000 beats per day; roughly fist-sized
6
Kidneys (pair)
The two bean-shaped kidneys filter the body's entire blood supply roughly 40 times per day, producing about 1.5 to 2 liters of urine. They regulate fluid balance, electrolyte concentrations, and blood pressure, and produce the hormone erythropoietin, which stimulates red blood cell production. Each kidney contains about 1 million nephrons, the functional filtering units.
System: UrinaryFunction: Blood filtration, waste removal, fluid and electrolyte balanceLocation: Retroperitoneal (back of abdomen)Note: Combined weight of both kidneys
7
Spleen
The spleen is the largest lymphatic organ and serves as a blood filter and reservoir. It removes old or damaged red blood cells, recycles iron, stores a reserve of blood (about one cup), and produces white blood cells that fight infection. The spleen can enlarge significantly (splenomegaly) in response to infection, liver disease, or blood disorders.
System: Lymphatic / ImmuneFunction: Blood filtration, iron recycling, immune response, blood reserveLocation: Left upper abdomen, behind the stomachNote: Largest lymphatic organ
8
Pancreas
The pancreas is a dual-function gland that produces digestive enzymes (exocrine) and hormones including insulin and glucagon (endocrine). It lies horizontally behind the stomach, about 15 cm long, and weighs about 70 grams. The islets of Langerhans, which produce insulin, make up only 1–2% of the pancreas's mass but are critical for blood glucose regulation.
System: Digestive / EndocrineFunction: Digestive enzyme production, insulin and glucagon secretionLocation: Retroperitoneal (behind the stomach)Note: About 15 cm long
9
Thyroid gland
The butterfly-shaped thyroid gland wraps around the front of the trachea (windpipe) just below the larynx. It produces the hormones T3 (triiodothyronine) and T4 (thyroxine), which regulate metabolism, heart rate, body temperature, and growth. Despite its small size, the thyroid influences nearly every organ system in the body.
System: EndocrineFunction: Metabolism regulation through T3 and T4 hormone productionLocation: Front of neck, below the larynxNote: Butterfly-shaped, two lobes connected by isthmus
10
Prostate gland
The prostate is a walnut-sized gland that sits below the bladder and surrounds the urethra in males. It secretes a slightly alkaline fluid that makes up 50–75% of semen volume, helping to protect and nourish sperm. The prostate typically weighs about 11 grams in young adults and tends to enlarge with age (benign prostatic hyperplasia), affecting over 50% of men by age 60.
System: Reproductive (male)Function: Secretes seminal fluid, contributes to semen volumeLocation: Pelvis, below the bladderNote: Male-specific organ; female analog is the Skene's gland
Ad · in-feed
Full comparison
#
Name
System
Function
Location
Note
1
Skin
Integumentary
Protection, temperature regulation, sensation, vitamin D synthesis
Entire body surface
Epidermis + dermis only (subcutaneous fat excluded)
2
Liver
Digestive
Detoxification, bile production, metabolism, glycogen storage
Right upper abdomen
Largest internal organ
3
Brain
Nervous
Cognition, coordination, sensory processing, motor control
Cranial cavity (skull)
~86 billion neurons; ~20% of body's energy use
4
Lungs (pair)
Respiratory
Gas exchange (oxygen in, carbon dioxide out)
Thoracic cavity (chest)
Combined weight of both lungs; right lung is heavier
5
Heart
Cardiovascular
Pumps blood through circulatory system
Mediastinum (center of chest, between lungs)
~100,000 beats per day; roughly fist-sized
6
Kidneys (pair)
Urinary
Blood filtration, waste removal, fluid and electrolyte balance
Retroperitoneal (back of abdomen)
Combined weight of both kidneys
7
Spleen
Lymphatic / Immune
Blood filtration, iron recycling, immune response, blood reserve
Left upper abdomen, behind the stomach
Largest lymphatic organ
8
Pancreas
Digestive / Endocrine
Digestive enzyme production, insulin and glucagon secretion
Retroperitoneal (behind the stomach)
About 15 cm long
9
Thyroid gland
Endocrine
Metabolism regulation through T3 and T4 hormone production
Front of neck, below the larynx
Butterfly-shaped, two lobes connected by isthmus
10
Prostate gland
Reproductive (male)
Secretes seminal fluid, contributes to semen volume
Pelvis, below the bladder
Male-specific organ; female analog is the Skene's gland
How we ranked this
Items are ranked by the average weight (in grams, rounded to the nearest gram) of each organ in a healthy adult human, as compiled from standard medical references including Gray's Anatomy, StatPearls, and the BBC Science Focus / BBC Future organ-weight dataset. The paired lungs and paired kidneys are listed as a single organ category with their combined weight; the skin figure includes the dermis and epidermis (the subcutaneous fat layer is excluded). Values are averages for an adult male of typical stature (70 kg / 154 lb). Individual variation is significant due to age, sex, body composition, and health status. Rank 1 is the heaviest organ.
FAQ
What is the largest organ in the human body?
The skin is the largest organ by both weight (about 4.5 kg / 10 lb) and surface area (about 1.5–2 square meters). The largest internal solid organ is the liver, at about 1.5 kg.
Which organ is the heaviest internal organ?
The liver is the heaviest internal organ, weighing about 1.5 kg (3.3 lb) in an average adult. The brain is second at about 1.5 kg, though the exact ranking depends on body size and sex.
Which organ consumes the most energy?
The brain consumes about 20% of the body's energy despite making up only about 2% of body weight, making it the most energy-intensive organ per gram.
Do organ weights change with age?
Yes. Most organs reach their peak weight in early adulthood and gradually decline with age. The brain loses 5–10% of its mass between ages 30 and 80, the heart can enlarge with age-related conditions, and the prostate typically enlarges in older men.
The 10 leading causes of death in the United States in 2023, by number of deaths, according to the CDC's National Center for Health Statistics (NCHS Data Brief No. 521).