The red cell distribution width (RDW) blood test measures how equal your red blood cells are in size. One of several tests included in a complete blood count (CBC), RDW is measured as a percentage ...

Additionally, in 2019, researchers concluded that a high RDW count correlates with a higher mortality risk from any cause. ... The calculation doctors use for this is (RDW-SD)/(MCV)×100.

A red cell distribution width (RDW) blood test helps measure variation in red blood cell volume and size. Learn why it’s performed and how to read results.