Extracellular fluid (ECF) or extracellular fluid volume (ECFV) usually denotes all body fluid outside of the cells. The remainder is called intracellular fluid.
In some animals, including mammals, the extracellular fluid can be divided into two major subcompartments, interstitial fluid and blood plasma. The extracellular fluid also includes the transcellular fluid, which comprises about 2.5 percent of the ECF.
In humans, the normal glucose concentration of extracellular fluid that is regulated by homeostasis is approximately 5 mM/L, and the pH is tightly regulated by buffers around 7.4. The volume of ECF is typically 15 L, of which 12 L is interstitial fluid and 3 L is plasma. Interstitial fluid makes up 16% of human body weight, and blood plasma, 4%.
see Extracellular matrix.