Albumin Globulin Ratio (A/G Ratio) Calculator
Enter your serum albumin and total protein values to calculate your albumin to globulin (A/G) ratio. The calculator also shows your globulin level and interprets whether your ratio falls in the normal, low, or high range. Switch between g/dL and g/L units to match your lab report.
Formula
Worked example
A patient with albumin 4.2 g/dL and total protein 7.2 g/dL: globulin = 7.2 - 4.2 = 3.0 g/dL; A/G ratio = 4.2 / 3.0 = 1.40, which is within the normal range of 1.0-2.5.
What is the albumin to globulin (A/G) ratio?
The albumin to globulin ratio, commonly written as the A/G ratio, compares the level of albumin in the blood to the level of globulins. Albumin is a single protein made by the liver that performs several vital jobs: it carries hormones, fatty acids, and drugs through the bloodstream, maintains osmotic pressure to keep fluid inside blood vessels, and reflects nutritional status. Globulins are a diverse family of proteins that includes immunoglobulins (antibodies), transport proteins such as transferrin and ceruloplasmin, and clotting factors. Because albumin and globulins respond differently to disease, their ratio provides a useful snapshot of liver function, kidney health, immune activity, and nutritional status. The A/G ratio is part of the comprehensive metabolic panel (CMP), one of the most ordered lab panels in routine care.
How is the A/G ratio calculated?
The calculation requires two values from your lab report: serum albumin and total serum protein. Globulin is not measured directly - it is derived by subtracting albumin from total protein. The A/G ratio is then albumin divided by that globulin figure. For example, if your albumin is 4.2 g/dL and your total protein is 7.2 g/dL, your globulin is 3.0 g/dL and your A/G ratio is 4.2 / 3.0 = 1.40. US labs report values in g/dL; international labs often use g/L, where values are 10 times larger but the ratio itself is identical because both numerator and denominator scale the same way.
What do low and high A/G ratios mean?
A low A/G ratio (below 1.0) means globulins outweigh albumin. The most common causes are liver disease (reduced albumin synthesis), nephrotic syndrome (selective albumin loss in urine), protein-losing enteropathy, multiple myeloma or other plasma cell disorders (overproduction of immunoglobulins), and autoimmune diseases such as lupus or rheumatoid arthritis. Severe infection, inflammatory bowel disease, hypothyroidism, and late-stage pregnancy can also lower the ratio. A high A/G ratio (above 2.5) is less common and typically reflects low globulin production due to genetic immunoglobulin deficiencies or certain leukemias, or a raised albumin level caused by dehydration. Neither extreme is diagnostic on its own - the ratio is a flag that prompts further testing such as serum protein electrophoresis, kidney function tests, or liver imaging.
Factors that affect your A/G ratio result
Several physiological and pre-analytical factors influence the reading. Dehydration concentrates all proteins and can raise albumin, pushing the ratio up. Inflammation of any cause - infection, surgery, trauma - triggers the acute-phase response, which lowers albumin (a negative acute-phase reactant) while raising some globulins, depressing the ratio. Pregnancy normally lowers albumin in the second and third trimesters, which can reduce the ratio without any disease process. Age matters too: albumin tends to decline slightly after age 65 due to lower dietary intake and reduced liver synthesis, so older adults may have ratios toward the lower end of normal. Some drugs, including corticosteroids and androgens, influence albumin levels. Always interpret your result alongside clinical context, not in isolation.
A/G Ratio and Component Protein Reference Ranges
| Measure | Low | Normal Range | High | Clinical Significance |
|---|---|---|---|---|
| A/G Ratio | < 1.0 | 1.0-2.5 | > 2.5 | Core diagnostic marker |
| Albumin (g/dL) | < 3.5 | 3.5-5.2 | > 5.2 | Liver synthesis, nutrition |
| Globulin (g/dL) | < 2.0 | 2.0-3.5 | > 3.5 | Immune activity, inflammation |
| Total Protein (g/dL) | < 6.0 | 6.0-8.3 | > 8.3 | Overall protein status |
Standard adult reference ranges; values may vary slightly by laboratory.
Frequently asked questions
What is a normal albumin to globulin ratio?
Most laboratories consider an A/G ratio between 1.0 and 2.5 to be normal, though some references cite 1.2-2.2. A ratio below 1.0 is generally considered clinically significant because it means globulins exceed albumin, which is unusual in a healthy adult. Ratios above 2.5 are less common and warrant review. Always use the reference range printed on your own lab report, as values can vary by laboratory and method.
Can I calculate the A/G ratio without a globulin measurement?
Yes, and this is actually how most labs report it. Serum globulin is almost never measured directly - it is derived by subtracting albumin from total protein. As long as you have your albumin and total protein values, this calculator works out your globulin and then divides to get the A/G ratio. Both values come from a standard comprehensive metabolic panel (CMP).
What does a low A/G ratio indicate?
A ratio below 1.0 suggests that globulins outweigh albumin. Common causes include liver disease (which reduces albumin synthesis), nephrotic syndrome (which causes albumin to leak into urine), multiple myeloma or other plasma cell disorders (which overproduce certain globulins), autoimmune diseases, and chronic infections or inflammatory conditions. A single low reading is a flag, not a diagnosis - your doctor will order additional tests to identify the cause.
What does a high A/G ratio indicate?
A high ratio (above 2.5) is usually due to low globulin levels rather than high albumin. This can occur with inherited immunoglobulin deficiencies, certain leukemias that suppress normal antibody production, or long-term corticosteroid use. A mildly elevated ratio from dehydration (which concentrates albumin) is also possible and resolves with rehydration. Your doctor will assess the result in context.
How do I convert between g/dL and g/L for this calculation?
Multiply g/dL by 10 to get g/L, and divide g/L by 10 to get g/dL. For example, albumin of 4.2 g/dL equals 42 g/L. Importantly, the A/G ratio itself does not change with the unit conversion, because both albumin and globulin scale by the same factor and the ratio cancels out. Use whichever unit matches your lab report and the calculator handles the rest.
Is the A/G ratio part of a routine blood test?
Yes. The A/G ratio is typically included as part of the comprehensive metabolic panel (CMP), which is one of the most commonly ordered routine blood tests. The CMP measures albumin and total protein among other values, so your A/G ratio can be calculated from any standard CMP result. Some labs print the ratio directly; others report only albumin and total protein, from which the ratio is easily derived.
Can the A/G ratio diagnose a specific disease?
No. The A/G ratio is a screening indicator, not a diagnostic test. An abnormal ratio signals that something may be affecting protein balance and prompts further investigation - typically serum protein electrophoresis, liver function tests, kidney panels, or immunoglobulin quantification depending on whether the ratio is low or high. A normal ratio does not rule out disease, and an abnormal ratio does not confirm any specific condition.