AST/ALT Ratio Calculator

Q: Is the AST/ALT ratio diagnostic on its own?

No. The AST/ALT ratio indicates a diagnostic pattern, not a standalone diagnosis. It should be interpreted alongside the absolute enzyme levels, other liver function tests, imaging, history, and the full clinical picture.

Pattern	AST/ALT Ratio
Common in NAFLD/NASH, chronic viral hepatitis	< 1.0
Consistent with acute viral hepatitis or mixed injury	1.0 – 2.0
Suggestive of alcoholic hepatitis or advanced fibrosis	≥ 2.0

Condition	Typical AST/ALT pattern
Alcoholic hepatitis	Ratio typically > 2.0. AST is usually elevated more than ALT, and both are often only modestly elevated (rarely > 300-500 U/L) despite significant liver injury.
Acute viral hepatitis	Ratio near 1.0, with both AST and ALT often markedly elevated (sometimes into the thousands) as the acute injury peaks.
NAFLD / NASH	Ratio typically < 1.0, with mild-to-moderate elevations in both enzymes and ALT usually higher than AST.
Chronic viral hepatitis	Ratio usually < 1.0, though the ratio can rise toward or above 1.0 as fibrosis progresses toward cirrhosis.
Cirrhosis (any cause)	Ratio often rises above 1.0 regardless of the original cause, as advanced fibrosis reduces ALT-producing hepatocyte mass more than AST.

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Walk-through

How to Use This Calculator

3 steps

1

Enter AST

Enter the AST (aspartate aminotransferase, also called SGOT) result from a liver panel or metabolic panel, in U/L (units per liter).

2

Enter ALT

Enter the ALT (alanine aminotransferase, also called SGPT) result from the same panel, also in U/L. Use values drawn from the same blood draw for a meaningful ratio.

3

Read the ratio and pattern

The calculator divides AST by ALT instantly and classifies the result into one of three patterns — below 1.0 (common in NAFLD/NASH), 1.0-2.0 (consistent with viral hepatitis), or 2.0 and above (suggestive of alcoholic hepatitis). Check the Interpretation tab to see your value highlighted against every range, and the Common Patterns tab for how the ratio behaves across specific liver conditions.

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Reference

Formula & Methodology

1 formula

AST/ALT ratio (De Ritis ratio)

Ratio = AST ÷ ALT

AST and ALT are both entered in U/L (units per liter). The result is a unitless ratio — the U/L units cancel out of the division. De Ritis F, Coltorti M, Giusti G first described the ratio in 1957 as a way to distinguish patterns of liver injury from the relative rise of these two enzymes.

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High YMYL

Trust, Methodology & Sources

Reviewed by Calculover Clinical Team · Updated 2026-07-23 · 2 sources

Editorial accountability

Author: Calculover Clinical Team - Clinical content team

Owner: Calculover Editorial - Editorial oversight

Reviewer: Calculover Clinical Team - Clinical reviewer

Last reviewed: 2026-07-23

Last verified: 2026-07-23

Data effective: 2026-07-23

Methodology

Implements the AST/ALT ratio (De Ritis ratio) described by De Ritis F, Coltorti M, Giusti G, Clin Chim Acta. 1957;2(1):70-74: Ratio = AST ÷ ALT, interpreted against a pattern of <1.0 (common in NAFLD/NASH), 1.0-2.0 (consistent with viral hepatitis), and >=2.0 (suggestive of alcoholic hepatitis), per Giannini EG, Testa R, Savarino V, CMAJ. 2005;172(3):367-379.

Assumption: AST and ALT are assumed to be measured from the same blood draw so the ratio reflects a single point in time.

Assumption: The calculator does not adjust for confounders such as muscle injury, cardiac events, medications, or hemolysis, all of which can shift AST or ALT independent of liver status.

Assumption: A single AST/ALT ratio is treated as a screening data point describing a pattern, not a diagnosis of any specific liver condition.

Limitations & guidance

AST is also present in skeletal muscle and the heart, so muscle injury, strenuous exercise, or a cardiac event can raise AST and shift the ratio upward independent of liver status.

The ratio's classic associations with alcoholic, viral, or fatty liver disease are patterns, not certainties — overlap between conditions is common, especially as fibrosis progresses.

Results are for clinical decision support and education only and do not replace a treating clinician's full assessment.

This clinical decision support tool calculates the De Ritis (AST/ALT) ratio for educational and clinical pattern evaluation only. A serum enzyme ratio is not diagnostic on its own. Results must be interpreted by a qualified healthcare professional in conjunction with absolute enzyme levels, patient history, physical examination, imaging, and full metabolic panels.

Professional guidance: This calculator is for clinical decision support and educational purposes only and is not a substitute for professional medical judgment, diagnosis, or treatment. Always consult a qualified clinician for patient care decisions.

Primary sources

De Ritis F, Coltorti M, Giusti G. "An enzymic test for the diagnosis of viral hepatitis: the transaminase serum activities." Clin Chim Acta. 1957;2(1):70-74.

Giannini EG, Testa R, Savarino V. "Liver enzyme alteration: a guide for clinicians." CMAJ. 2005;172(3):367-379.

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Glossary

Key Terms Explained

6 terms

De Ritis ratio Another name for the AST/ALT ratio, after De Ritis F, Coltorti M, Giusti G, who first described it in 1957 as a pattern that could help distinguish causes of liver injury.

AST/ALT ratio The result of dividing AST by ALT (AST ÷ ALT). A ratio below 1.0 is common in NAFLD/NASH, a ratio near 1.0 is classically associated with viral hepatitis, and a ratio above 2.0 is suggestive of alcoholic hepatitis.

Alcoholic hepatitis Liver inflammation caused by heavy alcohol use. It classically produces an AST/ALT ratio above 2.0, because alcohol-related injury raises AST disproportionately more than ALT.

Viral hepatitis Liver inflammation caused by a hepatitis virus (such as hepatitis A, B, or C). Acute viral hepatitis classically produces an AST/ALT ratio near 1.0, with both enzymes rising to a similar degree.

NAFLD Nonalcoholic fatty liver disease — fat accumulation in the liver not caused by heavy alcohol use. It typically produces an AST/ALT ratio below 1.0, with ALT rising more than AST.

Liver enzymes AST and ALT are enzymes released into the blood when liver cells are damaged. Both are reported in U/L on a standard metabolic or liver panel, and their relative levels — not just their absolute levels — carry diagnostic information.

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Scenarios

Real-World Examples

3 worked examples

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Alcoholic pattern

AST 140 U/L, ALT 60 U/L

AST 140 U/L ALT 60 U/L

140 ÷ 60 ≈ 2.33. A ratio above 2.0 is suggestive of alcoholic hepatitis, consistent with the AST-predominant pattern typically seen in alcohol-related liver injury.

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Viral pattern

AST 320 U/L, ALT 300 U/L

AST 320 U/L ALT 300 U/L

320 ÷ 300 ≈ 1.07. A ratio near 1.0 is a pattern classically associated with acute viral hepatitis, where AST and ALT rise to a similar degree even though both are markedly elevated.

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NAFLD pattern

AST 45 U/L, ALT 70 U/L

AST 45 U/L ALT 70 U/L

45 ÷ 70 ≈ 0.64. A ratio below 1.0 is common in NAFLD/NASH, where ALT typically rises more than AST despite only mild-to-moderate elevation of either enzyme.

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Deep Dive

Understanding the AST/ALT Ratio (De Ritis Ratio)

3 chapters · 3 min read

The AST/ALT ratio — also known as the De Ritis ratio — divides two liver enzymes to reveal a pattern, not just a level. This calculator computes the ratio and classifies it against the patterns most often described in alcoholic, viral, and fatty liver disease.

How the AST/ALT ratio works

The AST/ALT ratio is simply AST divided by ALT: Ratio = AST ÷ ALT. De Ritis F, Coltorti M, and Giusti G first described it in 1957, observing that the relative rise of these two transaminases — not just their absolute levels — differed by cause of liver injury.

Because it combines two values into one ratio, the AST/ALT ratio can point toward a likely pattern of injury even when both enzymes are individually elevated. A ratio below 1.0 is common in NAFLD/NASH, a ratio near 1.0 is classically seen in acute viral hepatitis, and a ratio above 2.0 is suggestive of alcoholic hepatitis.

Inputs and what they mean

AST (U/L) — aspartate aminotransferase, also called SGOT — is an enzyme found in the liver, heart, and skeletal muscle, released into the blood when those tissues are damaged.

ALT (U/L) — alanine aminotransferase, also called SGPT — is an enzyme found predominantly in the liver, making it a more liver-specific marker than AST. Both values should come from the same blood draw — mixing results from different dates can produce a misleading ratio.

Limits and edge cases

The AST/ALT ratio is a diagnostic pattern, not a diagnosis. AST is also present in skeletal muscle and the heart, so muscle injury, strenuous exercise, or a cardiac event can raise AST independent of liver status and shift the ratio upward. Medication effects, hemolysis, and lab assay variation can also distort the result. A single ratio should prompt correlation with absolute enzyme levels, other liver function tests, imaging, and clinical history — not stand alone as a diagnosis.

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Questions

Frequently Asked Questions

6 questions

What is the formula for the AST/ALT ratio?+

The AST/ALT ratio (De Ritis ratio) is calculated by dividing AST by ALT: Ratio = AST ÷ ALT. Both values are entered in U/L, and the resulting ratio is unitless since the U/L units cancel out of the division.

What does an AST/ALT ratio above 2 mean?+

An AST/ALT ratio above 2 is suggestive of alcoholic liver disease, such as alcoholic hepatitis. This pattern occurs because alcohol-related liver injury tends to raise AST disproportionately more than ALT.

What does an AST/ALT ratio around 1 mean?+

An AST/ALT ratio near 1 is a pattern classically associated with viral hepatitis. In this pattern, AST and ALT rise to a similar degree, unlike the AST-predominant pattern seen in alcoholic liver disease.

What does an AST/ALT ratio below 1 mean?+

An AST/ALT ratio below 1 is common in nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH), where ALT tends to rise more than AST despite only mild-to-moderate elevation of either enzyme.

Is the AST/ALT ratio diagnostic on its own?+

No — the AST/ALT ratio is a pattern only, not a standalone diagnosis. It should always be combined with the absolute enzyme levels, other liver function tests, imaging, history, and the full clinical picture before drawing any conclusion.

What units does the AST/ALT ratio calculator use?+

Enter AST and ALT in U/L (units per liter), the standard units reported on most metabolic and liver panels. The AST/ALT ratio itself is unitless, since the U/L units cancel out of the division.

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Liver Enzymes & Patient Baseline

AST/ALT Ratio & Diagnostic Interpretation

AST/ALT Ratio Reference Ranges

Common AST/ALT Patterns in Liver Disease

How to Use This Calculator

Enter AST

Enter ALT

Read the ratio and pattern

Formula & Methodology

Trust, Methodology & Sources

Key Terms Explained

Real-World Examples

Alcoholic pattern

Viral pattern

NAFLD pattern

Understanding the AST/ALT Ratio (De Ritis Ratio)

How the AST/ALT ratio works

Inputs and what they mean

Limits and edge cases

Frequently Asked Questions

Get a branded PDF of your results

AST/ALT Ratio Calculator

Liver Enzymes & Patient Baseline

AST/ALT Ratio & Diagnostic Interpretation

AST/ALT Ratio Reference Ranges

Common AST/ALT Patterns in Liver Disease

How to Use This Calculator

Enter AST

Enter ALT

Read the ratio and pattern

Formula & Methodology

Trust, Methodology & Sources

Key Terms Explained

Real-World Examples

Understanding the AST/ALT Ratio (De Ritis Ratio)

How the AST/ALT ratio works

Inputs and what they mean

Limits and edge cases

Frequently Asked Questions

Get a branded PDF of your results

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