Health charts that list “normal” numbers can be useful, but they can also be misleading when they present one number as correct for everyone.
Blood pressure, cholesterol, blood sugar, blood counts, vitamins, and electrolytes are interpreted differently depending on age, sex, pregnancy, medications, fasting status, medical history, and even the laboratory performing the test. MedlinePlus specifically notes that laboratories may use different methods and reference ranges, so your own lab report and healthcare professional should take priority over a number found online.
That said, understanding the commonly used ranges can make a medical report much less confusing.
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Here are 18 important health measurements, including several corrections to numbers that are commonly shared online.
1. Blood Pressure
Blood pressure is written as two numbers, such as 118/76 mm Hg.
The first number, systolic pressure, represents pressure in the arteries when the heart contracts.
The second, diastolic pressure, represents pressure while the heart relaxes between beats.
According to the American Heart Association, normal adult blood pressure is:
Systolic: less than 120 mm Hg
and
Diastolic: less than 80 mm Hg.
So 120/80 is not the exact target that everyone should have. Under current AHA categories, a systolic reading of 120–129 with a diastolic below 80 is considered elevated rather than normal.
One isolated reading also does not tell the whole story. Blood pressure changes with activity, stress, caffeine, illness, medications, and how the measurement is taken.
2. Resting Pulse
For most healthy adults at rest, a commonly cited pulse range is approximately:
60–100 beats per minute.
The image’s 70–100 range leaves out many healthy adults whose resting pulse naturally falls between 60 and 70.
Athletes and highly active people may have resting heart rates below 60 without it necessarily indicating a problem.
Age, physical fitness, medications, fever, dehydration, anxiety, and other factors can all influence heart rate.
3. Body Temperature
People often hear that normal temperature is exactly 37°C or 98.6°F.
Human temperature is actually a range.
MedlinePlus lists a typical resting adult range of approximately:
36.5°C–37.3°C
or
97.7°F–99.1°F.
Temperature can vary through the day and also depends on where it is measured. An oral, ear, forehead, rectal, or underarm reading may not be identical.
So a healthy person does not need to measure exactly 37°C.
4. Respiratory Rate
Respiratory rate means how many breaths a person takes each minute while resting.
For an average healthy resting adult, MedlinePlus gives approximately:
12–18 breaths per minute.
Age matters considerably here.
Children normally breathe faster than adults, so adult reference numbers should not simply be applied to infants or young children.
Breathing rate may also increase temporarily with exercise, fever, anxiety, pain, or illness.
5. Hemoglobin
Hemoglobin is the oxygen-carrying protein inside red blood cells.
Common adult reference ranges reported by MedlinePlus are approximately:
Men: 13.8–17.2 g/dL
Women: 12.1–15.1 g/dL.
These numbers can vary between laboratories and can be affected by altitude, pregnancy, dehydration, smoking, medical conditions, and other factors.
Low hemoglobin may occur with anemia, blood loss, iron deficiency, vitamin deficiencies, or other conditions.
A high result also has several possible explanations, so hemoglobin should never be interpreted alone.
6. Cholesterol
A single cholesterol number gives only part of the picture.
For adults, a commonly used target for total cholesterol is:
less than 200 mg/dL.
But a lipid panel also looks at LDL, HDL, and triglycerides.
MedlinePlus lists common targets including:
Total cholesterol: below 200 mg/dL
LDL: generally below 100 mg/dL
Triglycerides: below 150 mg/dL.
Someone’s appropriate LDL goal may be much lower if they have cardiovascular disease, diabetes, or a higher risk of heart attack or stroke.
So “cholesterol 130–200” should not be treated as one universal normal range.
7. Potassium
Potassium helps nerves, muscles, and the heart function properly.
A common serum reference range is approximately:
3.7–5.2 mEq/L, although individual laboratories may use slightly different limits.
A value around 3.5–5.0 is also commonly encountered on lab reports.
Both high and low potassium can sometimes be medically important because potassium affects heart rhythm and muscle function.
Kidney function, medications, vomiting, diarrhea, dehydration, and certain diseases can affect potassium levels.
8. Sodium
Sodium plays an important role in fluid balance and nerve and muscle function.
A common adult blood reference range is approximately:
135–145 mEq/L.
MedlinePlus gives 135–145 mEq/L on its comprehensive metabolic panel reference information, while another common panel lists 136–144.
That variation demonstrates why the range printed on your own laboratory report matters.
Blood sodium is also very different from the amount of sodium you eat during the day.
9. Triglycerides
This is one of the most important corrections to the original graphic.
A triglyceride level of 220 mg/dL is not considered a normal target.
For adults:
Less than 150 mg/dL — healthy
150–199 mg/dL — borderline high
200–499 mg/dL — high
500 mg/dL or higher — very high.
Therefore, a triglyceride result of 220 mg/dL would generally fall into the high category.
Extremely elevated triglycerides can also increase the risk of pancreatitis in addition to being associated with cardiovascular risk.
10. Blood Volume
An average adult has roughly:
5–6 liters of blood.
However, this is an estimate rather than a health target.
Blood volume varies according to body size, sex, pregnancy, hydration, and other physiological factors.
Unlike blood pressure or blood glucose, people do not normally monitor their blood volume at home.
It is mainly useful as an interesting physiological reference.
11. Blood Sugar
There is no single “normal blood sugar” number without knowing when the test was taken.
Was the person fasting?
Had they just eaten?
Was it a random glucose test?
Do they have diabetes and a personalized treatment target?
For a standard metabolic panel, fasting glucose is commonly around:
70–100 mg/dL, with individual laboratory ranges varying slightly.
The claim that children should universally be between 70 and 130 and adults between 70 and 115 is therefore too simplistic.
Children have age-specific considerations, and people with diabetes may be given individualized glucose goals by their healthcare team.
Context matters enormously with glucose.
12. Iron
The number 8–15 mg in the graphic should not be treated as a normal blood iron range.
Blood iron is normally measured in micrograms per deciliter (mcg/dL), not simply milligrams.
MedlinePlus provides example serum iron reference ranges of approximately:
Men: 59–158 mcg/dL
Women: 37–145 mcg/dL.
Even serum iron by itself does not give a complete picture.
Doctors may also examine ferritin, transferrin, total iron-binding capacity, iron saturation, hemoglobin, and other results when investigating possible iron deficiency or overload.
Serum iron can also fluctuate throughout the day.
That is why you should not diagnose iron deficiency from one simple number found on social media.
13. White Blood Cell Count
White blood cells help the immune system respond to infections and other threats.
A commonly used adult reference range is approximately:
4,500–11,000 cells per microliter.
Some laboratories may use a lower limit closer to 4,000.
A high white blood cell count can occur with infection, inflammation, medication effects, stress, and other conditions.
A low count also has many possible causes.
The total number is only part of the story. A CBC with differential can show how many neutrophils, lymphocytes, monocytes, eosinophils, and basophils are present.
14. Platelets
Platelets help blood clot.
A common adult reference range is:
150,000–400,000 platelets per microliter.
This is one number in the original graphic that is reasonably consistent with a commonly used range.
However, laboratories may vary slightly.
A very low platelet count can increase bleeding risk, while very high counts may occur for several different reasons and require medical interpretation.
15. Red Blood Cell Count
Red blood cells carry oxygen through the body.
The graphic simplifies the range to 4–6 million cells, but values are generally interpreted differently according to sex and laboratory.
MedlinePlus gives common adult ranges of approximately:
Men: 4.2–5.7 million cells/mcL
Women: 3.8–5.1 million cells/mcL.
Pregnancy, dehydration, altitude, smoking, lung conditions, anemia, kidney problems, and many other factors can influence the count.
RBC results are normally interpreted alongside hemoglobin, hematocrit, MCV, and other parts of the complete blood count.
16. Calcium
Calcium is important for bones, muscles, nerves, blood clotting, and many other body functions.
A common serum calcium range is approximately:
8.5–10.2 mg/dL.
The image lists 8.6–10.3 mg/dL, which is close to ranges used by some laboratories.
Again, your own lab’s reference interval is the correct comparison.
Blood calcium also does not directly tell you whether you are consuming enough calcium in your diet.
The body regulates blood calcium very tightly.
17. Vitamin D
Vitamin D is commonly assessed by measuring 25-hydroxyvitamin D [25(OH)D].
According to the NIH Office of Dietary Supplements:
20 ng/mL or higher is adequate for most people
Below 12 ng/mL is considered too low
and
above 50 ng/mL may be associated with adverse effects.
That means the frequently shared “20–50 ng/mL” range is a reasonable shorthand in some contexts, but it should not be interpreted as a universal ideal that everyone must remain inside.
Recommendations and interpretation can differ depending on medical circumstances.
More vitamin D is not automatically better.
18. Vitamin B12
Vitamin B12 helps make red blood cells and supports normal nerve function.
The image gives 200–900 pg/mL, but B12 interpretation is more complicated than a simple wide range.
The NIH notes that laboratories commonly consider serum or plasma vitamin B12 below approximately:
200–250 pg/mL
to be subnormal.
A borderline blood result does not always provide a definite answer.
When B12 is approximately 150–399 pg/mL and deficiency is still suspected, clinicians may use another test such as methylmalonic acid (MMA) to help clarify the result.
So someone should not assume that a value barely above 200 automatically rules out a problem.
Why “Normal Range” Does Not Always Mean “Healthy”
This may be the most important lesson from the entire list.
A reference range is a statistical tool.
It shows the range commonly observed in a particular reference population using a particular test method.
It does not mean that:
every result outside the range indicates disease,
or
every result inside the range guarantees perfect health.
MedlinePlus explains that healthy people can sometimes have results outside a laboratory reference range, while people with medical conditions can occasionally have results that fall inside one.
Doctors interpret numbers together with symptoms, medical history, medications, previous results, physical examination, and other testing.
Units Matter Just as Much as the Number
Never compare two laboratory values without checking the units.
For example:
Glucose may be measured in mg/dL or mmol/L.
Vitamin D may be reported as ng/mL or nmol/L.
Iron may be measured in mcg/dL.
Hemoglobin is commonly measured in g/dL.
Cell counts may appear as cells per microliter or as a value multiplied by 10⁹/L.
A number without its unit can be nearly meaningless.
This is one reason health graphics that list numbers without clearly explaining the test and measurement can create confusion.
Keep Your Own Results in Context
Knowing basic health numbers is useful.
It can help you understand a routine blood test and make conversations with a healthcare professional easier.
But the best number to compare with your result is usually the reference range printed directly beside it on your laboratory report, followed by the target your healthcare professional has recommended for your individual circumstances.
So rather than memorizing one giant chart, remember the bigger lesson:
Know what is being measured.
Check the units.
Know whether you were fasting.
Look at the laboratory’s reference range.
Consider age, sex, medications, pregnancy, and medical history.
And pay attention to trends over time rather than panicking over a single slightly unusual result.
Health numbers are valuable tools.
They become much more useful when we understand what they actually mean.