Hemoglobin
Hb
- Sample
- Blood
- Usual units
- g/dL
Also known as Hb · Hgb · Haemoglobin
What this test measures
Hemoglobin is the protein inside red blood cells that carries oxygen through the bloodstream. A blood test reports its concentration because it is the most direct measure of the blood's oxygen-carrying capacity, usually in grams per deciliter (g/dL).
Reading your report
There isn’t one standard range for this test — each lab prints its own. Use the range shown next to your result.
Hemoglobin unit converter
Convert Hemoglobin units
Labs print this test in g/dL or g/L depending on where the sample was run.
Related guides
- Guide
Why the same blood test has different "normal" ranges at different labs
Reference intervals are built from each lab's own population and equipment, which is why two labs can print different ranges for the same sample.
- Guide
Reference interval, cutoff, and the "optimal" numbers online: three different things
The range beside your result, the target a website quotes, and the threshold that defines a condition are built in different ways and answer different questions.
- Guide
Why the same lab printed a different reference range for you this year
Ranges are not fixed constants. The lab can change method, revise its reference group, or apply a range that depends on your age — none of which is an error.
- Guide
HbA1c and fasting glucose: a three-month average and a single moment
One is a snapshot of the morning you gave blood, the other reflects roughly three months. Why they can disagree, and what the estimated average glucose row is.
- Guide
Haemoglobin, haematocrit and the red cell indices: MCV, MCH, MCHC, RDW
A blood count reports the same red cells several ways — a count, a protein, a percentage, and four averages computed from them. What each column is measuring.
- Guide
What the H and L flags on a lab report actually assert
A flag compares your number to the range printed beside it on that page — nothing more. What it does not tell you, and why healthy people collect them.