- 01A reference range is a population description
Most ranges hold the middle 95% of a healthy reference group, so about 1 in 20 healthy results falls outside on any one test. A flag starts a question; it does not answer it.
- 02Your report's range beats any chart
Labs use different methods and set their own ranges, and sex, age, pregnancy and units shift them further. Read your number against the range printed beside it.
- 03Some lines are targets, not ranges
Cholesterol, A1c, fasting glucose and vitamin D are judged against guideline cutoffs tied to health outcomes, not against where healthy people happen to fall.
A normal blood test value is a reference range: the span that about 95% of healthy adults land in on one lab's method. The tables below give widely published adult ranges for the tests on most routine panels, each linked to its own marker page, but the range printed beside your result on your own report is the one that applies to you.
How to read this chart
A lab builds a reference range by testing a group of healthy people and keeping the middle 95% of their results. That design has a built-in consequence: about 5% of healthy people, 1 in 20, fall outside the range on any one test, and on a 20-test panel it is common for a healthy person to have a flag or two. The guide on reference ranges explains why in range is not the same as optimal, and the guide on lab units explains mg/dL, mmol/L and the rest.
MedlinePlus, the US National Library of Medicine's consumer reference, prints the same caveat under each of its lab tables:
Normal value ranges may vary slightly among different laboratories.MedlinePlus Medical Encyclopedia, CBC blood test 2
Complete blood count (CBC) normal values
The complete blood count counts and measures red cells, white cells and platelets. The CBC guide reads the whole panel, including the white cell differential; the ranges below are the core lines. 2
| Test | Typical adult range (US units) | SI units | Notes |
|---|---|---|---|
| Red blood cell count (RBC) | Men 4.6 to 6.2 million/mcL; women 4.2 to 5.4 million/mcL 2 | Men 4.6 to 6.2 x10^12/L; women 4.2 to 5.4 x10^12/L | Higher in men and at altitude |
| Hemoglobin | Men 13 to 18 g/dL; women 12 to 16 g/dL 2 | Men 130 to 180 g/L; women 120 to 160 g/L | Lower in pregnancy; low hemoglobin defines anemia |
| Hematocrit | Men 40% to 55%; women 36% to 48% 2 | Men 0.40 to 0.55; women 0.36 to 0.48 | Rises with dehydration |
| White blood cell count (WBC) | 4,500 to 11,000 cells/mcL 2 | 4.5 to 11.0 x10^9/L | Some healthy people, often of African ancestry, run lower |
| Platelet count | 150,000 to 400,000/mcL 2 | 150 to 400 x10^9/L | Often reported as 150 to 400 K/uL |
| MCV | 80 to 100 fL 2 | 80 to 100 fL | Average red cell size; small in iron deficiency, large in B12 or folate deficiency |
| MCH | 27 to 32 pg 2 | 27 to 32 pg | Hemoglobin per red cell |
| MCHC | 32 to 36 g/dL 2 | 320 to 360 g/L | Hemoglobin concentration in red cells |
Red cell results are read as a group. A low hemoglobin with a low MCV points one way and a low hemoglobin with a high MCV points another; the anemia guide walks through both.
Comprehensive metabolic panel (CMP) normal values
The comprehensive metabolic panel covers blood sugar, kidney function, electrolytes, liver enzymes and blood proteins. The basic metabolic panel (BMP) is the first eight rows below without the liver and protein tests. 1
| Test | Typical adult range (US units) | SI units | Notes |
|---|---|---|---|
| Glucose, fasting | 70 to 100 mg/dL 1 | 3.9 to 5.6 mmol/L | Diabetes guidelines treat 100 and above as raised (see the blood sugar table) |
| Blood urea nitrogen (BUN) | 6 to 20 mg/dL 1 | 2.1 to 7.1 mmol/L (as urea) | Rises with dehydration and high protein intake |
| Creatinine | 0.6 to 1.3 mg/dL 1 | 53 to 115 umol/L | Higher with more muscle; lower in women and older adults |
| Sodium | 135 to 145 mEq/L 1 | 135 to 145 mmol/L | Mostly reflects water balance |
| Potassium | 3.7 to 5.2 mEq/L 1 | 3.7 to 5.2 mmol/L | Can read falsely high if the sample was hemolyzed |
| Chloride | 96 to 106 mEq/L 1 | 96 to 106 mmol/L | Usually moves with sodium |
| CO2 (bicarbonate) | 23 to 29 mEq/L 1 | 23 to 29 mmol/L | Reflects acid-base balance |
| Calcium | 8.5 to 10.2 mg/dL 1 | 2.13 to 2.55 mmol/L | Read with albumin; see corrected calcium |
| Total protein | 6.0 to 8.3 g/dL 1 | 60 to 83 g/L | Albumin plus globulins |
| Albumin | 3.4 to 5.4 g/dL 1 | 34 to 54 g/L | Made by the liver; falls in illness and inflammation |
| Total bilirubin | 0.1 to 1.2 mg/dL 1 | 2 to 21 umol/L | Mildly high in Gilbert syndrome, which is harmless |
| Alkaline phosphatase (ALP) | 20 to 130 U/L 1 | 0.33 to 2.17 ukat/L | Higher in growing teens and in pregnancy |
| ALT | 4 to 36 U/L 1 | 0.07 to 0.60 ukat/L | Upper limits differ widely between labs |
| AST | 8 to 33 U/L 1 | 0.13 to 0.55 ukat/L | Also rises after hard exercise |
The metabolic panel is easiest to read in groups. BUN, creatinine and eGFR describe the kidneys, and the kidney function guide explains why an eGFR of 60 or higher is generally read as normal filtering when the urine shows no protein. Sodium, potassium, chloride and CO2 are read in the electrolytes guide, and ALT, AST, ALP and bilirubin in the liver enzymes guide.
Cholesterol and lipid panel values
Lipid results are judged against health targets, not against the spread of a healthy population. The values below are the general adult targets MedlinePlus lists for people aged 20 and over; a clinician may set lower goals for someone with diabetes or heart disease. 3 The lipid panel guide reads the lines together.
| Test | Healthy target (US units) | SI units | Notes |
|---|---|---|---|
| Total cholesterol | Below 200 mg/dL 3 | Below 5.2 mmol/L | A sum; read the parts |
| LDL cholesterol | Below 100 mg/dL 3 | Below 2.6 mmol/L | The main target in most guidelines |
| HDL cholesterol | 60 mg/dL or higher is best; below 40 (men) or below 50 (women) is low 3 | 1.55 mmol/L or higher; below 1.0 (men) or 1.3 (women) is low | Higher is generally better, up to a point |
| Non-HDL cholesterol | Below 130 mg/dL 3 | Below 3.4 mmol/L | Total minus HDL; counts every artery-clogging particle |
| Triglycerides | Below 150 mg/dL normal; 150 to 199 borderline; 200 or more high 3 | Below 1.7 mmol/L normal; 2.3 or more high | Rise after a meal |
The numbers your lipid panel implies
Enter three values, read LDL, non-HDL, and your ratio. Nothing leaves your browser.
Blood sugar and A1c values
Fasting glucose and hemoglobin A1c are read against the American Diabetes Association's diagnostic cutoffs. 4 A1c reflects average blood sugar over roughly three months; fasting glucose is a single morning snapshot. The ADA requires two abnormal results, from two tests or the same test repeated, to diagnose diabetes unless blood sugar is unmistakably high. 4 The blood sugar guide covers the rest of the panel.
| Test | Normal | Prediabetes range | Diabetes range |
|---|---|---|---|
| Fasting glucose | Below 100 mg/dL (below 5.6 mmol/L) | 100 to 125 mg/dL (5.6 to 6.9 mmol/L) 4 | 126 mg/dL or higher (7.0 mmol/L or higher) 4 |
| Hemoglobin A1c | Below 5.7% (below 39 mmol/mol) | 5.7% to 6.4% (39 to 47 mmol/mol) 4 | 6.5% or higher (48 mmol/mol or higher) 4 |
An example A1c of 5.9%%
Thyroid values
Thyroid ranges vary more between labs than most. TSH is the first line to read, then free T4; the thyroid panel guide owns the full read, including why TSH ranges shift with age and pregnancy.
MedlinePlus gives a typical adult TSH range of 0.4 to 4.8 mIU/L (the same number in microunits per millilitre), notes that TSH varies during the day, and says experts do not fully agree on where the upper limit should sit, so some labs use a different upper cutoff. 9
Free T4 is reported in ng/dL in the US and pmol/L elsewhere, and its range depends heavily on the assay, so read it against the range on your report. In pregnancy, TSH ranges are trimester-specific and generally lower; a non-pregnant range can misread a pregnant result.
Iron studies normal values
Iron tests are read as a set, because each one alone can mislead. Ferritin reflects stored iron, serum iron moves through the day and after meals, and TIBC and transferrin saturation show how much carrying capacity is in use.
| Test | Men | Women | Notes |
|---|---|---|---|
| Serum iron | 59 to 158 mcg/dL (10.6 to 28.3 umol/L) 5 | 37 to 145 mcg/dL (6.6 to 25.9 umol/L) 5 | Often higher in the morning 10; rises after an iron-rich meal |
| TIBC | 171 to 505 mcg/dL (30.6 to 90.3 umol/L) 5 | 149 to 492 mcg/dL (26.7 to 88.0 umol/L) 5 | Rises in iron deficiency and pregnancy; many labs print a narrower range |
| Transferrin saturation | 20% to 50% 5 | 15% to 45% 5 | Iron divided by TIBC |
| Ferritin | 30 to 400 ng/mL 6 | 13 to 150 ng/mL 6 | Same number in mcg/L; rises with inflammation |
Ferritin is the line most people search for, and it carries a trap: it rises with inflammation, infection and liver disease, so a ferritin inside the range does not always mean iron stores are full. The iron deficiency guide covers low ferritin, and the hemochromatosis guide covers high ferritin with high saturation.
Vitamin D and vitamin B12 values
Vitamin levels are read against adequacy cutoffs, and labs and guidelines draw those lines in different places. The ranges below come from the NIH Office of Dietary Supplements for vitamin D and from MedlinePlus for B12. 7 8
| Test | Level | What it usually means |
|---|---|---|
| Vitamin D, 25-hydroxy | Below 12 ng/mL (30 nmol/L) | Deficiency 8 |
| Vitamin D, 25-hydroxy | 12 to 20 ng/mL (30 to 50 nmol/L) | May be inadequate for bone health in some people 8 |
| Vitamin D, 25-hydroxy | 20 ng/mL (50 nmol/L) or higher | Adequate for bone and overall health in most people 8 |
| Vitamin D, 25-hydroxy | Above 50 ng/mL (125 nmol/L) | Linked to possible adverse effects 8 |
| Vitamin B12 | 299 to 1,054 pg/mL (219 to 773 pmol/L) | Normal range on MedlinePlus 7 |
| Vitamin B12 | Below 299 pg/mL (219 pmol/L) | Possible deficiency; often confirmed with methylmalonic acid 7 |
Many labs print a lower B12 cutoff than MedlinePlus, so the same B12 result can be flagged low at one lab and normal at another. A borderline B12 is where methylmalonic acid earns its place, and the B12 deficiency guide explains the grey zone. Some vitamin D labs flag anything below 30 ng/mL; the vitamin D deficiency guide explains why the cutoffs disagree.
What changes a normal range: sex, age, pregnancy and units
| Factor | Examples of what shifts | What to do with it |
|---|---|---|
| Lab and method | ALT upper limits, TSH, free T4, B12, ferritin and troponin all differ by assay | Compare a result with the range from the same lab; compare trends within one lab |
| Sex | Hemoglobin, hematocrit, RBC, ferritin, creatinine and serum iron run higher in men 2 5 6 | Check that your report used the range for your sex |
| Age | TSH drifts up with age, eGFR falls with age, ALP is higher in growing teens | Adult charts do not apply to children; some labs print age-specific ranges |
| Pregnancy | Hemoglobin falls as blood volume expands, ALP rises from the placenta, TSH ranges are trimester-specific | Pregnancy needs pregnancy ranges; ask which one was used |
| Units | Glucose 100 mg/dL is 5.6 mmol/L; cholesterol 200 mg/dL is 5.2 mmol/L | Check the unit before comparing with any chart, including this one |
| Timing and preparation | Glucose and triglycerides after eating, serum iron by time of day 10, CK and AST after exercise | Note how you prepared; see the guide on lab units and your clinic's instructions |
Converting between US and SI units
- Glucose: mg/dL divided by 18 gives mmol/L (100 mg/dL is about 5.6 mmol/L).
- Cholesterol (total, LDL, HDL, non-HDL): mg/dL divided by 38.67 gives mmol/L (200 mg/dL is about 5.2 mmol/L).
- Triglycerides: mg/dL divided by 88.57 gives mmol/L (150 mg/dL is about 1.7 mmol/L).
- Creatinine: mg/dL multiplied by 88.4 gives umol/L (1.0 mg/dL is about 88 umol/L).
- Hemoglobin: g/dL multiplied by 10 gives g/L (13.5 g/dL is 135 g/L).
- Vitamin D: ng/mL multiplied by 2.5 gives nmol/L (20 ng/mL is 50 nmol/L).
What to do with a result outside the range
- 1Check the flag and the range on your reportAn H or L flag means the result is outside that lab's range. How far outside matters: a sodium of 134 mEq/L and a sodium of 120 mEq/L both carry an L, and they mean very different things.
- 2Check the unitA glucose of 5.5 looks alarming only if you read it as mg/dL. Most apparent mismatches with a chart are unit mismatches.
- 3Read the neighboursA high BUN with a normal creatinine often points to dehydration; a high BUN with a high creatinine points to the kidneys. Related tests moving together say more than one flag.
- 4Look at the trendA value that has sat slightly outside the range for years is different from one that moved this month. A trend beats a single reading.
- 5Ask the clinician who ordered itThey know why the test was ordered and what else is going on. The guide on reading any lab result lists useful questions.
Citations
- MedlinePlus Medical Encyclopedia. Comprehensive metabolic panel. US National Library of Medicine.
- MedlinePlus Medical Encyclopedia. CBC blood test. US National Library of Medicine.
- MedlinePlus. Cholesterol levels: what you need to know. US National Library of Medicine.
- American Diabetes Association Professional Practice Committee. 2. Diagnosis and classification of diabetes: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1):S27-S49. doi:10.2337/dc26-S002.
- MedlinePlus Medical Encyclopedia. Serum iron test. US National Library of Medicine.
- MedlinePlus Medical Encyclopedia. Ferritin blood test. US National Library of Medicine.
- MedlinePlus Medical Encyclopedia. Vitamin B12 level. US National Library of Medicine.
- NIH Office of Dietary Supplements. Vitamin D: fact sheet for health professionals.
- MedlinePlus Medical Encyclopedia. TSH test. US National Library of Medicine.
- MedlinePlus. Iron tests. US National Library of Medicine.
Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.
