What is the largest organ in the human body?

• A. Liver
• B. Skin
• C. Heart
• D. Kidney

Answer: (B)

Think about what counts as an organ and how big it is. The skin qualifies as an organ because it’s made up of multiple tissue layers that work together to protect the body, regulate temperature, provide sensation, and help with vitamin D production. It covers the entire outside of the body, giving you a very large surface area—roughly about 2 square meters in an average person—and it accounts for a noticeable portion of body weight. That combination of being an integrated, functional system and occupying the largest area on the body is why the skin is considered the largest organ overall. The liver is large, but skin’s overall size makes it bigger when you look at the whole body.