Quick answer
A CBC blood test counts and sizes the cells in your blood. It reports red cells (RBC, hemoglobin, hematocrit and the indices MCV, MCH, MCHC and RDW), white cells (WBC) and platelets (PLT, MPV). A CBC with differential also splits white cells into neutrophils, lymphocytes, monocytes, eosinophils and basophils. It needs no fasting, costs $29 with differential at Labcorp OnDemand, and is used to look for anemia, infection, inflammation and blood disorders (MedlinePlus).
CBC values and normal ranges
Ranges are Cleveland Clinic's adult ranges. Your lab's will differ slightly; use the ones on your report.
| Value | Code | Typical adult range | What it tells you |
|---|---|---|---|
| White blood cells | WBC | 4,000 to 10,000 per µL (4.0 to 10 K/µL) | Infection, inflammation, bone marrow |
| Red blood cells | RBC | Women 4.0 to 5.4 million per µL; men 4.5 to 6.1 million | Number of oxygen carriers |
| Hemoglobin | HGB | Women 11.5 to 15.5 g/dL; men 13 to 17 g/dL | Oxygen-carrying protein; low means anemia |
| Hematocrit | HCT | Women 36% to 48%; men 40% to 55% | Share of blood that is red cells |
| Mean corpuscular volume | MCV | 80 to 100 fL | Average red cell size |
| Mean corpuscular hemoglobin | MCH | 27 to 31 pg | Hemoglobin per cell |
| MCH concentration | MCHC | 32 to 36 g/dL | Hemoglobin concentration in cells |
| Red cell distribution width | RDW | 12% to 15% | Variation in red cell size |
| Platelets | PLT | 150,000 to 400,000 per µL | Clotting cells |
| Mean platelet volume | MPV | 7.0 to 9.0 fL | Average platelet size |
Cleveland Clinic adult ranges (women or people taking estrogen; men or people taking testosterone). Labs vary slightly.
Cleveland Clinic adult ranges.
Hematocrit is roughly three times hemoglobin in most people, so the two move together. Dehydration raises both; heavy drinking of fluids or pregnancy lowers both without any change in red cell mass.
Red cell indices: MCV, MCH, MCHC, RDW
When hemoglobin is low, the indices tell you what kind of anemia it is. MedlinePlus uses them to sort anemia by cell size:
| Pattern | MCV | Common causes | Next test |
|---|---|---|---|
| Small cells (microcytic) | Under 80 fL | Iron deficiency, thalassemia trait | Ferritin, iron, TIBC |
| Normal-size cells (normocytic) | 80 to 100 fL | Recent blood loss, chronic disease, kidney disease | Reticulocytes, creatinine |
| Large cells (macrocytic) | Over 100 fL | Low B12 or folate, alcohol, liver disease, some medicines | B12, folate |
RDW adds a clue: a high RDW with low MCV fits iron deficiency (cells of mixed sizes as new small cells join old ones), while a normal RDW with low MCV is more typical of thalassemia trait. Low MCH and MCHC (pale cells) usually travel with low MCV.
White cells and the differential
| Cell type | Code | Typical range per µL | Often high with | Often low with |
|---|---|---|---|---|
| Neutrophils | NEUT, ANC | 2,500 to 7,000 | Bacterial infection, stress, steroids, smoking | Some medicines, viral infection, chemotherapy |
| Lymphocytes | LYMPH | 1,000 to 4,800 | Viral infection | Steroids, some infections, immune problems |
| Monocytes | MONO | 200 to 800 | Chronic infection or inflammation | Rarely significant alone |
| Eosinophils | EOS | Under 500 | Allergy, asthma, parasites | Rarely significant |
| Basophils | BASO | Under 300 | Allergy, some marrow disorders | Rarely significant |
A slightly high WBC after a cold, a hard workout or a stressful week is common. A very high or very low count, or immature cells on the smear, needs a doctor's review.
Platelets
Platelets plug leaks in blood vessels. Counts under 150,000 per µL (thrombocytopenia) can come from viral infections, some medicines, heavy alcohol use or an enlarged spleen; bleeding risk rises mainly at much lower levels. Counts over 400,000 (thrombocytosis) are most often a reaction to inflammation, infection or iron deficiency (MedlinePlus). A platelet count is one of the values most affected by finger-prick collection: a Rice University study found drop-to-drop variation about 4 times higher than in venous blood.
What can throw off a CBC
| Factor | Effect | What to do |
|---|---|---|
| Dehydration | Hemoglobin and hematocrit read high because plasma volume is low | Drink normally before the draw |
| Smoking and living at altitude | Hemoglobin runs higher | Compare with your own past results |
| A cold or infection in the past 2 weeks | WBC and platelets can rise; lymphocytes shift | Retest once you are well |
| Hard exercise the day before | WBC can rise for hours | Rest the day before |
| Pregnancy | Hemoglobin falls as plasma volume expands | Pregnancy-specific ranges apply |
| Recent blood donation | Hemoglobin and ferritin fall for weeks | Wait at least 8 weeks for a baseline |
| Finger-prick collection | More drop-to-drop variation, especially platelets | Prefer venous or larger capillary samples |
Worked example: a low hemoglobin
A made-up CBC for a 34-year-old woman with heavy periods who feels tired:
| Value | Result | Flag | Reading |
|---|---|---|---|
| HGB | 11.0 g/dL | L | Mild anemia (range 11.5 to 15.5) |
| HCT | 34% | L | Matches the hemoglobin |
| MCV | 74 fL | L | Small cells |
| MCH | 24 pg | L | Pale cells |
| RDW | 16.8% | H | Mixed sizes: points to iron deficiency over thalassemia |
| PLT | 420,000 per µL | H | Iron deficiency can nudge platelets up |
| WBC | 6,200 per µL | Normal |
This is the textbook microcytic pattern. The next step is iron studies: a ferritin of, say, 9 ng/mL would confirm low iron stores. She should see her doctor, both to treat it and to find the cause. Our iron test guide and low ferritin symptoms page cover the follow-up, and blood tests for fatigue lists what else to check.
CBC at home: what SiPhox offers
Every SiPhox core panel except Thyroid Focus and Hormone Focus reports hemoglobin and a calculated hematocrit. A full CBC is an optional add-on at +$45 per test on EasyDraw panels. According to SiPhox's panel data it reports 8 values: HCT, HGB, MCH, MCHC, MCV, RBC, RDW and WBC. It does not include platelets or a white cell differential, so it cannot replace a lab CBC where those matter. Blood counts are also the markers most sensitive to capillary sampling; see are at-home blood tests accurate.
| Value | Lab CBC with differential | SiPhox CBC add-on | SiPhox core panels |
|---|---|---|---|
| HGB, HCT | Yes | Yes | Yes (hematocrit calculated) |
| RBC, MCV, MCH, MCHC, RDW | Yes | Yes | No |
| WBC | Yes | Yes | No |
| Platelets, MPV | Yes | No | No |
| Differential (5 white cell types) | Yes | No | No |
| Collection | Venous, at a lab | Capillary, upper arm at home | Capillary, upper arm at home |
CBC cost
| Option | Price | Notes |
|---|---|---|
| Labcorp OnDemand CBC with differential | $29 | Venous, all values including platelets |
| Labcorp OnDemand Comprehensive Health Test | $189 | CBC plus CMP, lipids, HbA1c, urinalysis |
| SiPhox Longevity Essentials plus CBC add-on | $194 per test | 31 markers plus 8 CBC values, at home |
| SiPhox Ultimate 360 plus CBC add-on | $319 per test | 62 markers incl. ferritin, iron, TIBC, B12, folate, plus CBC |
Which test to choose
| If you want | Test | Choose |
|---|---|---|
| Platelets, the differential or a check during an infection | Venous CBC with differential | Labcorp OnDemand, $29, or your doctor |
| A one-off anemia check | CBC plus ferritin | Any lab |
| To track hemoglobin alongside heart and hormone markers | Hemoglobin and hematocrit | SiPhox Longevity Essentials (included) |
| To track anemia and iron repletion at home | CBC values plus ferritin, iron, TIBC, B12, folate | SiPhox Ultimate 360 with the CBC add-on |
Decoding the codes on your report? See blood test abbreviations. The CBC is usually ordered with a CMP.
Longevity Essentials
The default panel: heart, metabolic, hormone and inflammation markers in one draw.
Check price
Ultimate 360
Everything on the four core panels plus iron studies, B12 and folate, GGT and PSA.
Check price
Frequently asked questions
Do you need to fast for a CBC?
No. A CBC does not change with meals. If it is drawn with a CMP or glucose test, fast for those instead.
What does a CBC blood test show?
Your red cells (count, hemoglobin, size), white cells (count, and types if a differential is added) and platelets. It is used to look for anemia, infection, inflammation and blood disorders.
What is a CBC with differential?
A CBC plus a breakdown of white cells into neutrophils, lymphocytes, monocytes, eosinophils and basophils, which helps tell a bacterial infection from a viral one or an allergy.
Can a CBC detect cancer?
A CBC can show abnormal counts or cells that prompt more tests for blood cancers such as leukemia, but it cannot diagnose or rule out most cancers.
How much does a CBC cost without insurance?
Labcorp OnDemand lists a CBC with differential at $29 (checked 30 September 2026). SiPhox offers an 8-value CBC as a +$45 add-on to its home panels.
Sources
- MedlinePlus: Complete blood count (CBC)
- Cleveland Clinic: Complete blood count (CBC), normal ranges
- MedlinePlus: Red blood cell (RBC) indices
- MedlinePlus: Blood differential test
- MedlinePlus: Platelet tests
- Bond and Richards-Kortum, Am J Clin Pathol 2015: drop-to-drop variation in fingerprick blood
- Labcorp OnDemand: Complete blood count with differential
- Labcorp OnDemand: Comprehensive Health Test
- SiPhox Health: Longevity Essentials panel page (add-ons including CBC)
- SiPhox Health panel comparison