Normal Haemoglobin Level by Age & Gender

Quick Answer

A normal haemoglobin (Hb) level for a healthy adult is generally 13.2 to 16.6 g/dL for men and 11.6 to 15.0 g/dL for women, according to Mayo Clinic Laboratories. Haemoglobin is highest at birth (13.4 to 20.0 g/dL), dips through infancy and childhood, rises again at puberty, and stays sex-differentiated for the rest of adult life because testosterone stimulates red blood cell production. A result below range points toward anaemia. A result above range points toward polycythaemia, a condition involving excess red blood cells. Exact cutoffs vary slightly between laboratories, so always read your number against the reference range printed on your own report rather than a figure copied from the internet.

What Is Haemoglobin, and Why Does the “Normal” Range Keep Changing?

Haemoglobin is the iron-rich protein packed inside red blood cells. Its job is to bind oxygen in the lungs, carry it to every organ and muscle in the body, and bring carbon dioxide back to the lungs to be exhaled. It’s measured as part of a complete blood count (CBC), one of the most frequently ordered blood tests in medicine, alongside related values like haematocrit, MCV, MCH, and MCHC.

Unlike blood glucose, haemoglobin doesn’t have one universal “normal” number. It shifts predictably across the lifespan for three physiological reasons:

• The fetal-to-newborn transition. In the womb, oxygen levels are relatively low, so babies are born with unusually high haemoglobin to compensate. This falls sharply over the first 2 to 3 months (reaching its lowest point between 6 to 12 weeks) as the baby starts breathing air directly.
• Puberty and sex hormones. Testosterone stimulates the bone marrow to produce more red blood cells. That’s why male and female reference ranges start to diverge around age 11 to 15 and remain distinct for the rest of adulthood.
• Iron needs and blood loss. Women and growing children need more iron than adult men. Menstruation, pregnancy, and periods of rapid growth can all increase the body’s iron needs, which is why iron levels may be lower in these groups.

Normal Haemoglobin Level by Age and Gender: The Complete Chart

The table below reflects the pediatric-through-adult reference intervals published by Mayo Clinic Laboratories, one of the most widely cited clinical laboratory standards worldwide. All values are in grams per decilitre (g/dL).

Source: Mayo Clinic Laboratories reference intervals.

Note: Compare your own result to the age band and column that match you, not to the “adult” row alone. A haemoglobin of 12.0 g/dL is a healthy result for a 6-year-old but would flag as low-normal for an adult man. If you’re tracking a child’s growth or your own levels over time, testing at the same time of year and ideally the same lab helps you spot genuine trends rather than lab-to-lab noise.

Why Your Lab Report Might Show Slightly Different Numbers

Reference ranges may vary somewhat laboratory to laboratory and country to country due to different reference populations and testing methods. Here’s what some trusted sources have to say about adult ranges:

Sources: Mayo Clinic Laboratories; Cleveland Clinic Laboratories; NIH/MedlinePlus; NIH/NCBI Bookshelf ("Haemoglobin and Haematocrit," Clinical Methods, 3rd ed.); North Bristol NHS Trust (Severn Pathology) haemoglobin reference range.

The differences mainly reflect the reference population, testing equipment, and regional demographics not differences in physiology. All five show the same pattern: adult men generally have haemoglobin levels about 1.5–2 g/dL higher than women, with some overlap.

A 13.5 g/dL reading might be considered normal by one reference but slightly lower than the other. This is why the doctor uses the reference range specified on your personal lab results rather than using the chart.

Haemoglobin vs. Haematocrit: What’s the Difference?

These two values are often confused because they move together, but they measure different things:

• Haemoglobin (Hb) measures the concentration of the oxygen-carrying protein itself, in g/dL.
• Haematocrit (Hct) measures the percentage of your total blood volume made up of red blood cells.

As a rule of thumb, haematocrit is roughly three times the haemoglobin value (the "Rule of Three"). A haemoglobin of 15 g/dL, for example, usually corresponds to a haematocrit near 45%. Dehydration typically causes both haemoglobin and haematocrit to rise proportionally due to hemoconcentration, preserving this 3:1 ratio. A true mismatch between the two generally indicates erythrocyte size or hemoglobinization abnormalities (such as severe microcytosis or hypochromia) or severe hemolysis, serving as a diagnostic clue for clinicians.

WHO Haemoglobin Thresholds for Diagnosing Anaemia

Lab reference ranges and WHO’s anaemia cutoffs are not exactly the same thing. A reference range shows the haemoglobin levels most often seen in healthy people, while WHO’s cut-offs help identify when haemoglobin is low enough to be called anaemia. For the first time in decades, the WHO revised these cutoffs in 2024, using data from people around the world.

The 2024 WHO update revised two paediatric age groups. For children 6–23 months the anaemia cut off is now <10.5 g/dL (previously 11.0 g/dL). For children aged 24–59 months (2–4 years), the threshold is <11.0 g/dL, while for children aged 5–11 years, the threshold is <11.5 g/dL.

Anaemia remains common worldwide, affecting roughly 3 in 10 women and 4 in 10 children, with the greatest burden in low- and middle-income countries.

The 2024 analysis also suggested a slightly higher haemoglobin cutoff for men—around 13.5 g/dL—compared with WHO’s current 13.0 g/dL threshold. However, WHO kept the existing cutoff because some uncertainty remains in the evidence. There also isn’t enough global data to set a separate cutoff for adults over 65. Instead, doctors consider the standard adult range alongside other health markers. Anaemia is nevertheless more common with age, affecting over 10% of people aged 65+ living in the community, more than 40% of hospitalized older adults, and up to 47% of nursing home residents.

Note: The WHO does not set standardized diagnostic population cutoffs for infants aged 0–6 months due to rapid physiological haemoglobin shifts (neonatal physiological nadir).

Haemoglobin in Pregnancy

In pregnancy, haemoglobin levels decrease naturally because the blood plasma increases more rapidly than red blood cells. This is a normal change and doesn’t mean something is wrong. The levels are likely to drop the most in the 2nd trimester and then rise a bit in the 3rd.

Both low and unusually high haemoglobin levels are monitored during pregnancy. Low levels are linked with a higher risk of preterm birth and low birth weight, while unusually high levels may indicate that blood volume hasn’t expanded normally and can be linked to stillbirth risk.

That’s why haemoglobin is checked throughout pregnancy as part of routine antenatal care.

What Causes Low Haemoglobin (Anaemia)?

If your haemoglobin is below the expected range for your age and sex, it may indicate anaemia, meaning your blood isn’t carrying as much oxygen as your body needs. It’s very common worldwide, affecting around 1.9 billion people. Women are affected more often than men.

Some of the most common causes include:

• Iron deficiency, the single most common cause worldwide, usually from low dietary iron intake, heavy menstrual bleeding, or slow, ongoing gastrointestinal blood loss
• Vitamin B12 or folate deficiency, which impairs red blood cell production
• Chronic diseases, including chronic kidney disease, rheumatoid arthritis, and cancer
• Acute or chronic blood loss from injury, surgery, or internal bleeding
• Bone marrow disorders that reduce the marrow’s ability to make new red blood cells
• Hemolytic anaemia, where red blood cells are destroyed faster than the body can replace them

Typical symptoms include persistent fatigue, pale skin or gums, shortness of breath on exertion, dizziness or light-headedness, cold hands and feet, a rapid or irregular heartbeat, and difficulty concentrating.

How it’s diagnosed: a plain Hb test confirms the number, but pinning down why it’s low usually takes iron, B12, and folate studies alongside it. The Max Anemia Profile bundles haemoglobin with these markers in one home visit, rather than ordering each test separately after the fact.

How Severe Is Low Haemoglobin? The NCI Grading Scale

Beyond the simple “normal vs. low” line, the U.S. National Cancer Institute (NCI) publishes a standardized severity scale, the Common Terminology Criteria for Adverse Events (CTCAE), that clinicians use to grade anaemia once it’s identified. It’s a useful reference point for understanding how concerning a given number actually is:

Source: National Cancer Institute, Common Terminology Criteria for Adverse Events (CTCAE), Version 5.0.

This scale was originally built for grading anaemia during cancer treatment, but it’s widely used as a general reference point for how urgently a low result needs attention. It’s a useful sense-check: a haemoglobin of 11.5 g/dL in a woman is mildly below the typical adult range and rarely urgent, while a haemoglobin of 7 g/dL is a different clinical situation entirely and needs prompt medical evaluation.

Practical Ways to Support Healthy Haemoglobin Levels

If a test shows mild, iron-deficiency-pattern anaemia, a clinician may recommend some combination of the following. The underlying cause should always be identified first, since eating more iron won’t fix anaemia caused by chronic disease or blood loss:

• Eat iron-rich foods regularly: Incorporate foods such as meat, poultry, fish, lentils, beans, tofu, spinach, and fortified cereals into your diet.
• Pair plant-based iron with vitamin C: Foods such as oranges, tomatoes, and bell peppers will help in the absorption of iron.
• Avoid tea or coffee with meals: They can reduce how much iron your body absorbs.
• Treat the underlying cause: This may include managing heavy periods, addressing digestive-tract blood loss, or treating a B12 or folate deficiency.
• Retest after a few weeks of treatment: This helps confirm that your haemoglobin levels are improving instead of relying only on whether your symptoms feel better.

What Causes High Haemoglobin (Polycythaemia)?

Haemoglobin above the normal range is less common but equally worth investigating. Non-disease causes include:

• Living at high altitude, where the body compensates for thinner air by producing more red blood cells
• Chronic smoking, which raises carboxyhaemoglobin levels and triggers extra red blood cell production
• Dehydration, which concentrates the blood and can temporarily inflate the reading without any real increase in red cell mass

Some health conditions can also cause high haemoglobin, including polycythaemia vera, chronic lung disease, sleep apnoea, and right-sided heart failure. If haemoglobin stays high across repeated tests, generally above 16.5 g/dL in men and 16.0 g/dL in women, it’s worth getting it checked further. High haemoglobin can make the blood thicker, which may increase the risk of blood clots.

When Should You See a Doctor or Get Tested?

Talk to a healthcare provider, and consider getting a haemoglobin test, if:

• You haven’t had a CBC or haemoglobin check in the last 12 months, especially if you’re a woman of reproductive age, pregnant, vegetarian or vegan, or over 65
• Your last result was borderline or outside the reference range
• You have symptoms of anaemia (persistent fatigue, pale skin, breathlessness) even if a past result looked normal
• You’re pregnant and due for a routine antenatal check
• You have a chronic condition (kidney disease, inflammatory disease, cancer) that requires ongoing monitoring
• A high reading needs to be confirmed on a repeat test

A single haemoglobin number is never interpreted in isolation. A doctor weighs it alongside haematocrit, red blood cell indices (MCV, MCH, MCHC), iron studies, symptoms, and personal and family medical history, which is exactly what a full CBC panel provides.

Getting a Haemoglobin Test Done

A haemoglobin test is usually done as part of a CBC and doesn’t require any special preparation. You don’t need to fast you can eat and drink as usual before the test.

The test can be done at a diagnostic lab, hospital, routine check-up, or through home sample collection. A trained phlebotomist collects the blood sample at your home and sends it to an accredited lab for testing.

Home collection can be especially convenient for pregnant women, older adults, and people who need regular health monitoring but find frequent lab visits difficult.

Whichever route you choose, the result is only useful when read against the reference range printed on that specific report, ideally with a doctor’s input if the number falls outside the expected range for your age and sex.

Frequently Asked Questions

What is a normal haemoglobin level for a woman?

Normal haemoglobin values in adult women fall within the range of 11.6 to 15.0 g/dL (Mayo Clinic Laboratories); however, some references give a range up to 15.3 g/dL. According to the WHO’s 2024 guidelines, haemoglobin value below 11.0 g/dL in the first trimester and 10.5 g/dL in the second trimester is considered anaemia among pregnant women.

What is a normal haemoglobin level for a man?

The normal range of haemoglobin for adult males is from 13.2 to 16.6 g/dL (Mayo Clinic Laboratories). The normal haemoglobin level for men is high compared to that for women since the hormone testosterone increases the production of red blood cells.

What is a normal haemoglobin level for a child?

It depends heavily on age. A 2-year-old’s normal range is about 10.2 to 12.7 g/dL, while a 9 to 10-year-old’s range rises to roughly 11.8 to 14.7 g/dL. Newborns start much higher still, at about 13.4 to 20.0 g/dL, before falling sharply over the first 2 to 3 months (reaching its lowest point between 6 to 12 weeks).

Can dehydration or altitude change a haemoglobin reading?

True. The process of dehydration makes the blood concentration high, and this can cause the artificial increase of haemoglobin levels; the rehydration will make it fall back to the normal level. Haemoglobin levels increase due to the high altitude because the body produces more red blood cells.

Is a haemoglobin level of 10 g/dL dangerous?

A haemoglobin of 10 g/dL sits below the normal adult range for both men and women and indicates mild-to-moderate anaemia. It’s not usually a medical emergency by itself, but it should be evaluated to find the underlying cause, such as iron deficiency, chronic blood loss, or a chronic illness, rather than left unaddressed.

How common is low haemoglobin (anaemia) worldwide?

The comprehensive Global Burden of Disease study reporting 1.92 billion people (24.3% of the world population) living with anaemia in 2021 was published in The Lancet Haematology in 2023 (led by the Institute for Health Metrics and Evaluation - IHME). About 3 in 10 women and 4 in 10 children worldwide are anaemic, according to WHO.

Is the normal haemoglobin range the same in the UK as in the US?

It’s very close but not identical. The NHS (via North Bristol NHS Trust) lists a normal adult range of 130 to 170 g/L (13.0 to 17.0 g/dL) for men and 120 to 150 g/L (12.0 to 15.0 g/dL) for women, which sits within the same overall band as Mayo Clinic’s and Cleveland Clinic’s U.S. reference ranges. The small differences reflect each health system’s own reference population rather than a real difference in what’s biologically normal.

Do I need to fast before a haemoglobin test?

No. A haemoglobin test doesn’t require fasting. You can eat and drink normally beforehand, whether the sample is taken at a lab or through a home collection service.

Can a haemoglobin test be done at home?

Yes. There are many diagnostics companies that provide services where a sample is collected from the patient’s home for the test of haemoglobin and complete blood count (CBC), such as MaxAtHome in India.

How soon are haemoglobin test results usually available?

Standard lab processing, including through home collection services, typically returns results within about 24 hours, delivered as a digital report.