AST/ALT Ratio Calculator — De Ritis Ratio

Calculate the AST/ALT ratio (De Ritis ratio) from your liver panel and see what the pattern typically suggests, alongside individual normal-range checks.

July 7, 2026

AST (U/L)

ALT (U/L)

Non-specific to advancing-fibrosis pattern

AST/ALT = 1.00

A ratio near 1 is non-specific — it doesn't strongly point toward one liver disease pattern over another on its own.

AST/ALT ratio = AST ÷ ALT (the De Ritis ratio). This is one data point among many used in liver disease assessment, not a diagnosis — it's typically interpreted alongside FIB-4, imaging, and a full clinical picture rather than on its own. Lab-specific reference ranges vary; check the ranges printed on your own lab report.

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Reference Values

Last verified: Jul 6, 2026

Category	Range	What It Means	Status
Ratio Below 1	AST/ALT < 1.0	ALT exceeds AST. Pattern more consistent with non-alcoholic fatty liver disease (NAFLD/NASH) or viral hepatitis (B or C), where ALT tends to rise more than AST in earlier disease stages.	Good
Ratio Near 1	AST/ALT ≈ 1.0	Non-specific — AST and ALT are roughly equal. Doesn't strongly point toward one liver disease pattern over another on its own.	Okay
Ratio Above 1	AST/ALT > 1.0	AST exceeds ALT. Can indicate advancing fibrosis or cirrhosis in patients with chronic liver disease, since AST clearance slows as liver architecture is damaged.	Okay
Ratio Above 2 (classic cutoff)	AST/ALT > 2.0	The most-cited teaching cutoff — highly suggestive of alcoholic liver disease or alcoholic hepatitis. A minority of sources use a lower cutoff of 1.5 instead; both are in clinical use.	Poor
Normal AST	Roughly 10-40 U/L	Typical reference range for aspartate aminotransferase, though the exact cutoff varies by lab and assay method.	Good
Normal ALT	Roughly 10-40 U/L	Typical reference range for alanine aminotransferase, though the exact cutoff varies by lab and assay method.	Good

Source: PMC "The De Ritis Ratio: The Test of Time" (AST/ALT ratio clinical interpretation and cutoffs); Medscape AST and ALT reference range pages (normal 10-40 U/L convention, lab-specific variation noted)

Worked Examples

AST 25, ALT 40 (Ratio Below 1)

AST: 25 U/L
ALT: 40 U/L

AST/ALT = 0.63

25 ÷ 40 = 0.63. ALT exceeds AST — pattern more consistent with NAFLD or viral hepatitis than alcohol-related liver disease. ALT is also above the typical 10-40 U/L normal range.

AST 30, ALT 30 (Ratio Near 1)

AST: 30 U/L
ALT: 30 U/L

AST/ALT = 1.00

30 ÷ 30 = 1.00. Both values sit inside the normal 10-40 U/L range, and a ratio of exactly 1 is non-specific — it doesn't point toward a particular liver disease pattern on its own.

AST 60, ALT 40 (Ratio Above 1)

AST: 60 U/L
ALT: 40 U/L

AST/ALT = 1.50

60 ÷ 40 = 1.50. AST is elevated above the normal range and exceeds ALT — can suggest advancing fibrosis or cirrhosis in the context of known chronic liver disease. This also crosses the alternate 1.5 cutoff some sources use for alcoholic liver disease.

AST 120, ALT 45 (Ratio Above 2 — Classic Cutoff)

AST: 120 U/L
ALT: 45 U/L

AST/ALT = 2.67

120 ÷ 45 = 2.67. Above the classic 2.0 cutoff most cited by Medscape and VeryWellHealth — highly suggestive of alcoholic liver disease or alcoholic hepatitis. Both AST and ALT are also individually elevated above the normal 10-40 U/L range.

AST 15, ALT 12 (Both Normal, Ratio Above 1)

AST: 15 U/L
ALT: 12 U/L

AST/ALT = 1.25

15 ÷ 12 = 1.25. Both enzymes fall comfortably inside the normal 10-40 U/L range. A ratio above 1 with both values normal is generally far less concerning than the same ratio with elevated absolute values — the ratio is only meaningful in the context of the individual numbers.

How to Use This Calculator

1

Enter AST

Aspartate aminotransferase value in U/L from your liver panel.
2

Enter ALT

Alanine aminotransferase value in U/L from the same panel.
3

Read the ratio and interpretation banner

The calculator divides AST by ALT and shows which clinical pattern that ratio is typically associated with.
4

Check the individual range flags

AST and ALT are each compared to the typical 10-40 U/L normal range, since the ratio alone doesn't show whether either value is actually elevated.

What Each Value Means

AST/ALT Ratio (De Ritis Ratio) (ratio (unitless)): AST divided by ALT. The relationship between the two values, rather than either one alone, that can hint at which liver disease pattern is more likely.
AST (Aspartate Aminotransferase) (U/L): A liver enzyme also found in heart and skeletal muscle, released into the blood when cells are damaged. Used as the numerator in the AST/ALT ratio.
ALT (Alanine Aminotransferase) (U/L): A liver-specific enzyme, making it a more targeted marker of liver cell damage than AST alone. Used as the denominator in the AST/ALT ratio.

Frequently Asked Questions

What is the AST/ALT ratio (De Ritis ratio)?

It's simply AST divided by ALT — two liver enzymes measured on a standard liver panel, both reported in U/L. The result is called the De Ritis ratio, named after Fernando De Ritis, who first described its clinical usefulness in the 1950s. Unlike either enzyme alone, the ratio between them can hint at which type of liver condition is present, not just that liver damage exists.

What does an AST/ALT ratio above 2 mean?

A ratio above 2 is the most commonly cited cutoff for a pattern suggestive of alcoholic liver disease or alcoholic hepatitis, per sources including Medscape and VeryWellHealth. A minority of references use a lower cutoff of 1.5 instead. Either way, a high ratio alongside elevated absolute AST and ALT values is more clinically meaningful than a high ratio with both enzymes in the normal range.

What does an AST/ALT ratio below 1 mean?

A ratio below 1 (meaning ALT is higher than AST) is a pattern more consistent with non-alcoholic fatty liver disease (NAFLD/NASH) or viral hepatitis (B or C), where ALT tends to rise more than AST, especially earlier in the disease course. This is the opposite pattern from alcoholic liver disease, which is why the ratio is useful for narrowing down likely causes.

Is a normal AST/ALT ratio the same as normal liver function?

Not necessarily. A ratio can look normal (near 1) even when both AST and ALT are elevated together — the ratio only describes the relationship between the two numbers, not whether either one is outside the normal range. This calculator checks AST and ALT individually against the typical 10-40 U/L range in addition to computing the ratio, since both pieces of information matter.

Can the AST/ALT ratio diagnose liver disease on its own?

No. The De Ritis ratio is a supporting clue, not a diagnostic test — it's typically interpreted alongside the absolute enzyme levels, other liver panel results, imaging, and validated scores like FIB-4, and always in the context of a patient's full clinical picture and history (including alcohol use). Ratios can also shift with cirrhosis regardless of the original cause, which limits how much weight any single reading should carry.