AST ALT Ratio Calculator
Calculate the AST-to-ALT (De Ritis) ratio from your liver panel. Enter AST and ALT in U/L to get the ratio and the pattern it classically suggests — but read it only when the enzymes themselves are abnormal.
Example: with AST (U/L) 45 · ALT (U/L) 20 → AST : ALT ratio: 2.25 : 1.
- Classic interpretationAbove 2 — classically linked to alcoholic liver disease, especially with a raised GGT
- ContextAST 45 U/L, ALT 20 U/L — the ratio is only meaningful when the enzymes are elevated
Computed by the calculator below using its default values. Change any input to see your own numbers.
De Ritis ratio = AST ÷ ALT (both U/L). A ratio above 2, especially with a high GGT, classically suggests alcoholic liver disease; below 1 is typical of NAFLD and early viral hepatitis.
What the De Ritis ratio hints at
AST and ALT are enzymes that leak from injured liver cells, but they are not identical. ALT lives mostly in the liver, while AST also comes from muscle, heart, and red blood cells and sits partly inside mitochondria. Dividing AST by ALT — the De Ritis ratio — captures the mix of injury. In most everyday liver problems, including non-alcoholic fatty liver disease and early viral hepatitis, ALT runs higher, so the ratio sits below 1.
A ratio climbing above 2 tells a different story. Alcohol damages mitochondria and depletes a cofactor ALT needs, pushing AST relatively higher; paired with a raised GGT, that pattern classically points to alcoholic liver disease. A rising ratio in chronic hepatitis can also flag advancing fibrosis or cirrhosis.
Why the ratio needs context
The ratio is close to meaningless when both enzymes are normal — small normal values can produce any ratio by chance. It also gets distorted by non-liver AST sources: a hard workout, a muscle injury, or hemolysis can raise AST and inflate the ratio without any liver disease. Always read it against the absolute enzyme levels, GGT, and the clinical picture.
How it’s calculated
De Ritis ratio = AST ÷ ALT, both in U/L (IU/L). Interpretation bands used: below 1 typical of NAFLD and early viral hepatitis; 1 to 2 nonspecific; above 2 classically alcoholic liver disease, especially with elevated GGT. A ratio above 1 in chronic liver disease can also suggest advancing fibrosis.
The ratio is only informative when transaminases are abnormal, and AST also rises from muscle, heart, and hemolysis. This is educational — diagnosis needs a clinician with the full panel and history.
AST/ALT ratio patterns
| Ratio | Classic association |
|---|---|
| Under 1 | Non-alcoholic fatty liver disease, early viral hepatitis, healthy |
| About 1 | Acute viral or toxic hepatitis (can vary) |
| 1 to 2 | Nonspecific; possible advancing fibrosis |
| Over 2 | Alcoholic liver disease (with high GGT); cirrhosis |
Source: De Ritis ratio patterns as described in hepatology references; interpret with absolute enzyme levels.
Common mistakes
- Interpreting the ratio when AST and ALT are both normal — it is meaningless there.
- Forgetting AST rises from muscle and hemolysis, inflating the ratio without liver disease.
- Treating a ratio over 2 as proof of alcohol use rather than one supportive clue.
- Ignoring GGT and bilirubin, which sharpen what the ratio suggests.
Frequently asked questions
What is the AST/ALT ratio formula?
It is AST divided by ALT, both measured in U/L. For instance, an AST of 45 and ALT of 20 gives a ratio of 2.25 to 1.
What does an AST/ALT ratio over 2 mean?
A ratio above 2, particularly alongside a raised GGT, is classically associated with alcoholic liver disease. It can also appear in cirrhosis. It supports a suspicion rather than confirming a cause.
What does a ratio below 1 suggest?
A ratio under 1 is typical of non-alcoholic fatty liver disease and early viral hepatitis, where ALT tends to exceed AST. Many healthy people also sit below 1.
Why does the ratio need the actual enzyme levels?
When both enzymes are normal, the ratio is unreliable and can take any value. It only carries meaning once transaminases are elevated, and even then AST from muscle or hemolysis can skew it.
Should I interpret this myself?
Use it to understand your report, then review it with a doctor. They combine it with GGT, bilirubin, imaging, and your history to reach a diagnosis this ratio alone cannot provide.