Hematocrit
What it measures, and what changes the number.
Hematocrit is the proportion of the blood's volume that is taken up by red blood cells. It is part of the complete blood count and gives a sense of how concentrated the red cells are in the blood.
It is read together with Hemoglobin and the Red blood cells count, which describe the same red cell mass in different ways, and with red cell indices such as MCV, MCHC and RDW that describe the size and hemoglobin content of the cells.
Most modern analyzers calculate hematocrit from the red cell count and the average cell size, while older methods spin the blood in a tube and measure the packed cells directly; the two can differ slightly. Hydration, posture and a long tourniquet time during the draw can concentrate or dilute the sample. Labs may print it as Hematocrito or Hematòcrit.
Reference ranges labs publish
Each lab states an interval for its own method and the population it measured. They differ, they are not interchangeable, and none of them is a verdict on a single result.
- Men, adults: 38.3 to 48.6 % · method not stated · Source: Mayo Clinic Laboratories, CBC (Complete Blood Cell Count (CBC) with Differential, Blood) (read 2026-09-24)
- Women, adults: 35.5 to 44.9 % · method not stated · Source: Mayo Clinic Laboratories, CBC (Complete Blood Cell Count (CBC) with Differential, Blood) (read 2026-09-24)
Often read alongside: Hemoglobin, Red blood cells, MCV, MCHC, RDW