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Bicarbonate (CO₂)

Blood

Bicarbonate (CO₂)

Also known as: HCO3

COMMON RANGE

22 – 29

mEq/L

2.3

34.7

Mayo Clinic Laboratories

Adult Male

↗

See all sources ↓

CONVERT & COMPARE

mEq/L

mmol/L

Reference ranges across 10+ sources

Adult reference ranges from 6 entries across 4 named sources, shown in mEq/L. Compare side-by-side.

SOURCE

SEX

AGE

RANGE

VISUAL

CITE

Mayo Clinic Laboratories

Male

8y–18y

21 – 29 mEq/L

↗

Mayo Clinic Laboratories

Male

≥18y

22 – 29 mEq/L

↗

Mayo Clinic Laboratories

Female

≥10y

22 – 29 mEq/L

↗

Labcorp

All

≥18y

20 – 29 mEq/L

↗

RCPA / AACB Australasian Harmonised Reference Intervals

All

≥18y

22 – 32 mEq/L

↗

UK Pathology Harmony

All

≥18y

22 – 29 mEq/L

Mayo Clinic Laboratories

Male · 8y–18y

↗

21 – 29 mEq/L

Mayo Clinic Laboratories

Male · ≥18y

↗

22 – 29 mEq/L

Mayo Clinic Laboratories

Female · ≥10y

↗

22 – 29 mEq/L

Labcorp

All · ≥18y

↗

20 – 29 mEq/L

RCPA / AACB Australasian Harmonised Reference Intervals

All · ≥18y

↗

22 – 32 mEq/L

UK Pathology Harmony

All · ≥18y

22 – 29 mEq/L

Ages 0–17 (CALIPER)

PEDIATRIC

14 age- and sex-stratified entries from the Canadian Laboratory Initiative on Pediatric Reference Intervals.

SOURCE

SEX

AGE

RANGE

VISUAL

CITE

CALIPER — Canadian Pediatric Reference Intervals

All

0–15d

5 – 20 mEq/L

↗

CALIPER — Canadian Pediatric Reference Intervals

All

15d–1y

10 – 24 mEq/L

↗

CALIPER — Canadian Pediatric Reference Intervals

All

1y–5y

14 – 24 mEq/L

↗

CALIPER — Canadian Pediatric Reference Intervals

All

5y–15y

17 – 26 mEq/L

↗

CALIPER — Canadian Pediatric Reference Intervals

Female

15y–19y

17 – 26 mEq/L

↗

CALIPER — Canadian Pediatric Reference Intervals

Male

15y–19y

18 – 28 mEq/L

↗

Mayo Clinic Laboratories

Male

1y–3y

17 – 25 mEq/L

↗

Mayo Clinic Laboratories

Male

3y–4y

18 – 26 mEq/L

↗

Mayo Clinic Laboratories

Male

4y–6y

19 – 27 mEq/L

↗

Mayo Clinic Laboratories

Male

6y–8y

20 – 28 mEq/L

↗

Mayo Clinic Laboratories

Female

1y–4y

18 – 25 mEq/L

↗

Mayo Clinic Laboratories

Female

4y–6y

19 – 26 mEq/L

↗

Mayo Clinic Laboratories

Female

6y–8y

20 – 27 mEq/L

↗

Mayo Clinic Laboratories

Female

8y–10y

21 – 28 mEq/L

↗

CALIPER — Canadian Pediatric Reference Intervals

All · 0–15d

↗

5 – 20 mEq/L

CALIPER — Canadian Pediatric Reference Intervals

All · 15d–1y

↗

10 – 24 mEq/L

CALIPER — Canadian Pediatric Reference Intervals

All · 1y–5y

↗

14 – 24 mEq/L

CALIPER — Canadian Pediatric Reference Intervals

All · 5y–15y

↗

17 – 26 mEq/L

CALIPER — Canadian Pediatric Reference Intervals

Female · 15y–19y

↗

17 – 26 mEq/L

CALIPER — Canadian Pediatric Reference Intervals

Male · 15y–19y

↗

18 – 28 mEq/L

Mayo Clinic Laboratories

Male · 1y–3y

↗

17 – 25 mEq/L

Mayo Clinic Laboratories

Male · 3y–4y

↗

18 – 26 mEq/L

Mayo Clinic Laboratories

Male · 4y–6y

↗

19 – 27 mEq/L

Mayo Clinic Laboratories

Male · 6y–8y

↗

20 – 28 mEq/L

Mayo Clinic Laboratories

Female · 1y–4y

↗

18 – 25 mEq/L

Mayo Clinic Laboratories

Female · 4y–6y

↗

19 – 26 mEq/L

Mayo Clinic Laboratories

Female · 6y–8y

↗

20 – 27 mEq/L

Mayo Clinic Laboratories

Female · 8y–10y

↗

21 – 28 mEq/L

About Bicarbonate (CO₂)

A carbon dioxide (CO2) blood test measures the amount of carbon dioxide in your blood. Carbon dioxide is an odorless, colorless gas. It is a waste product from metabolism, the process your body uses to make energy from food you eat.

Most of the carbon dioxide in your body is in the form of bicarbonate (HCO3), which is a type of electrolyte. Electrolytes are electrically charged minerals that help control the amount of fluid and the balance of acids and bases (pH balance) in your body.

Your blood carries carbon dioxide to your lungs, and then you breathe it out. Too much or too little carbon dioxide in your blood can be a sign of a health problem.

Main source: MedlinePlus ↗

Useful for

Often part of a group of tests called an electrolyte panel, which may be part of a routine checkup.

May help diagnose or monitor conditions related to an electrolyte imbalance, including high blood pressure and diseases of the kidneys, lungs, or liver.

Check for side effects of certain medicines that can cause electrolyte imbalances.

Main source: MedlinePlus ↗

Interpretation

Abnormal test results may be a sign that your body is having a hard time keeping the right acid-base balance (pH balance).

Too much CO2 in the blood can be a sign of many conditions, including lung diseases, Cushing's syndrome, kidney failure, and metabolic alkalosis.

Too little CO2 in the blood may be a sign of Addison disease, diabetic ketoacidosis, shock, metabolic acidosis, and respiratory alkalosis.

If your test results are not in the normal range, it doesn't necessarily mean you have a medical condition that needs treatment. Your provider may order other tests to confirm a diagnosis.

For general wellness information only. Talk to a clinician about your specific results.

Main source: MedlinePlus ↗

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Related biomarkers

Often tested alongside bicarbonate (co₂) or part of the same panel.

White Blood Cells (WBC)

Blood

Red Blood Cells (RBC)

Blood

Hemoglobin (Hgb)

Blood

Hematocrit (Hct)

Blood

Platelets (PLT)

Blood

Mean Corpuscular Volume (MCV)

Blood

Sources

Mayo Clinic Laboratories

Labcorp

RCPA / AACB Australasian Harmonised Reference Intervals

UK Pathology Harmony

CALIPER — Canadian Pediatric Reference Intervals

Last updated 2026-05-02

This page aggregates publicly available reference data and clinical information from Mayo Clinic Laboratories and other sources. For general wellness information only — not medical advice. For diagnosis or treatment of any condition, talk to a qualified clinician.

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