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Blood health

Hematocrit

Also known as: Hct, Packed cell volume (PCV), Crit, Erythrocyte volume fraction

A hematocrit (Hct) test measures the percentage of your blood volume occupied by red blood cells. Since red blood cells carry hemoglobin — the protein that transports oxygen throughout the body — hematocrit provides insight into your blood’s oxygen-carrying capacity.

The test is a standard part of a complete blood count (CBC), one of the most common blood panels ordered by healthcare providers. Abnormal hematocrit levels may point toward conditions like anemia, dehydration, lung disease, or bone marrow disorders.

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Key takeaways

  • Sample required: Blood

  • Tests for: Proportion of blood volume made up of red blood cells (RBCs); often used to help evaluate anemia, dehydration, polycythemia, and other conditions.

  • Healthy range: About 41–50 percent for men and 36–44 percent for women, though values vary by lab, age, sex, and environment (e.g., high altitude).

What can a hematocrit test tell you?

A hematocrit test can provide valuable information about your overall health, but it is not diagnostic on its own. Instead, it helps healthcare providers evaluate for possible conditions when combined with your symptoms, medical history, and other lab results.

Providers may use hematocrit testing to:

  • Help evaluate anemia and determine its possible cause (iron deficiency, chronic disease, or bone marrow issues).

  • Monitor treatment for conditions affecting red blood cell levels.

  • Assess hydration status, since dehydration can artificially elevate hematocrit. Support evaluation of conditions like chronic lung disease or polycythemia vera.

What is being tested?

Hematocrit reflects the proportion of blood volume made up of red blood cells. For example, a hematocrit of 42 percent means 42 percent of the blood’s volume consists of RBCs, while the rest includes plasma, white blood cells, and platelets.

Red blood cells are crucial because they carry hemoglobin, which binds oxygen in the lungs and delivers it to tissues throughout the body. Low hematocrit can mean fewer red blood cells are available to transport oxygen, while high hematocrit can signal concentrated blood or an overproduction of RBCs.

Where is the hematocrit test typically included?

The hematocrit test is almost always performed as part of a complete blood count (CBC). A CBC measures multiple components of blood, including:

  • Red blood cell (RBC) count

  • Hemoglobin White blood cell (WBC) count

  • Platelet count

Together, these results help providers assess for a wide range of conditions, from infections to nutritional deficiencies to blood cancers.

Who should get a hematocrit test?

A hematocrit test may be ordered in several situations:

  • Routine health check-ups. Most providers include a CBC in annual wellness exams.

  • Symptom evaluation. If you report fatigue, dizziness, pallor, shortness of breath, or weakness, a provider may order hematocrit testing.

  • Monitoring chronic conditions. People with kidney disease, lung disease, or blood disorders may have regular CBCs to track hematocrit.

  • Risk factors. Those with a family history of anemia, polycythemia, or certain chronic illnesses may undergo testing more frequently.

  • Before surgery. Hematocrit is sometimes checked to ensure safe oxygen-carrying capacity before procedures.

How Labs by Hims works

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Not available in all 50 states. Eligibility and provider order required. Lab results alone are not intended to diagnose, treat, or cure any condition. A provider will reach out about critical results and plans include access to 24/7 provider messaging.

Images for illustrative purposes only.

Frequently asked questions

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What causes changes in hematocrit levels? 

Hematocrit levels can shift for various reasons related to hydration, oxygen levels, nutrition, and red blood cell production. Higher hematocrit may occur with dehydration, when blood becomes more concentrated, or with chronic hypoxia from conditions like lung disease, sleep apnea, or living at high altitudes. 

Low hematocrit is more common and can result from iron deficiency anemia or other nutritional deficiencies, chronic diseases such as kidney disease or cancer, blood loss, or bone marrow suppression due to medications or chemotherapy. 

Can a hematocrit test be done at home?

Some mail-in kits include hematocrit as part of a CBC processed by a clinical lab. Stand-alone consumer hematocrit devices are uncommon.

 Does a hematocrit test require fasting?

No. A hematocrit test usually does not require fasting.

How long do results take?

Lab results are often available within a few hours to a day, depending on where the test is performed.

How often should I get a hematocrit test?

Frequency depends on your health. Many adults are tested during annual check-ups. Those with chronic conditions may need more frequent monitoring.

Is hematocrit testing covered by insurance?

Yes, hematocrit testing is typically covered when ordered by a provider as part of a CBC. Insurance is not required with lab testing through Hims.

What tests are related to this biomarker?

• Complete Blood Count (CBC)

• Hemoglobin

• Iron studies

• Reticulocyte count

• Erythropoietin level

The information provided here is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always talk to a qualified healthcare provider about your specific health concerns.

Related biomarkers

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Hemoglobin

Hemoglobin is the protein inside your red blood cells that carries oxygen to your muscles and brain. Being in the healthy range means your blood cells have what they need to move oxygen to your tissues successfully.

Learn more about Hemoglobin

Mean Corpuscular Hemoglobin Concentration (MCHC)

Mean corpuscular hemoglobin concentration (MCHC) measures the average concentration of hemoglobin in your red blood cells, which reflects how effectively they carry oxygen. When MCHC is in the healthy range, it indicates that the body is likely not experiencing any red blood cell disorders or iron deficiency.

Learn more about Mean Corpuscular Hemoglobin Concentration (MCHC)

Mean Corpuscular Hemoglobin (MCH)

Mean corpuscular hemoglobin (MCH) measures the average amount of hemoglobin in each red blood cell, which shows how well your blood can carry oxygen. A healthy level means your blood has enough hemoglobin for proper oxygen transport.

Learn more about Mean Corpuscular Hemoglobin (MCH)

Mean Corpuscular Volume (MCV)

Mean corpuscular volume (MCV) measures the average volume of your red blood cells, which can help reveal early signs of nutrient deficiencies or other blood conditions.

Learn more about Mean Corpuscular Volume (MCV)

Mean Platelet Volume (MPV)

Mean platelet volume (MPV) measures the average volume of your blood platelets, which play an essential role in blood clotting. When your MPV is in the healthy range, it suggests that your platelet volume is normal.

Learn more about Mean Platelet Volume (MPV)

Platelet Count

Platelets are the blood cells that help your body form clots, stopping bleeding when needed. A healthy platelet count means your body generally supports normal blood clotting when necessary.

Learn more about Platelet Count

Red Blood Cell Count

Red blood cells are responsible for carrying oxygen throughout your body. Your healthy red blood cell count is helping your organs and tissues function at their best.

Learn more about Red Blood Cell Count

Red Cell Distribution Width (RDW)

Red cell distribution width (RDW) measures the variation in the size of your red blood cells, which can help detect early signs of anemia or other blood conditions. A healthy RDW suggests that your red blood cells are uniform and efficiently transporting oxygen throughout your body.

Learn more about Red Cell Distribution Width (RDW)

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Reviewed by Felix Gussone, MD

Published 11/19/2025