Hemoglobin: What It Is and What Your Results Mean
Bottom line: Hemoglobin carries oxygen in your red blood cells. Normal is 12-17.5 g/dL depending on sex. Low levels indicate anemia.
What Is Hemoglobin?
Hemoglobin is the protein in red blood cells that carries oxygen from your lungs to every tissue in your body and returns carbon dioxide to your lungs for exhalation. It is measured as part of a complete blood count (CBC).
Low hemoglobin, called anemia, means your blood is carrying less oxygen than it should. This can cause fatigue, weakness, shortness of breath, and pale skin. Anemia has many causes, including iron deficiency, chronic disease, blood loss, and bone marrow disorders.
High hemoglobin can occur from dehydration, smoking, living at high altitude, or certain blood disorders. Both low and high levels warrant medical evaluation.
Hemoglobin Reference Ranges
| Classification | Range (g/dL) |
|---|---|
| Severely Low (Severe Anemia) | Below 8.9 |
| Low (Moderate Anemia) | 8.0 - 10.9 |
| Mildly Low (Mild Anemia) | 11.0 - 12.4 |
| Normal | 12.5 - 17.5 |
| High | 17.6 - 20.0 |
| Very High | 20.1 - 25.0 |
What Affects Your Hemoglobin Levels?
- Iron intake and absorption
- Vitamin B12 and folate levels
- Blood loss (menstruation, GI bleeding)
- Chronic diseases and inflammation
- Bone marrow function
- Altitude and smoking status
When to Get Tested
Hemoglobin is routinely checked during annual physicals as part of a CBC. More frequent testing if you have symptoms of anemia (fatigue, weakness, pale skin) or a known blood disorder.
Look Up Your Hemoglobin Result
Select your value below to see a detailed breakdown of what it means:
Severely Low (Severe Anemia)
Low (Moderate Anemia)
Mildly Low (Mild Anemia)
Normal
High
Very High
Read the Full Blood Test Guide
Frequently Asked Questions
For women, 12.0-16.0 g/dL is normal. For men, 14.0-18.0 g/dL is normal. Values vary slightly between laboratories.
The most common cause is iron deficiency, often from inadequate dietary iron, blood loss, or poor absorption. Other causes include vitamin B12 deficiency, chronic disease, and bone marrow disorders.
If low hemoglobin is caused by iron deficiency, eating iron-rich foods (red meat, spinach, lentils, fortified cereals) combined with vitamin C to enhance absorption can help. Severe deficiency may require iron supplements.
