AST/ALT Ratio Calculator
Enter your AST and ALT lab values (U/L) to calculate the De Ritis ratio.
Educational use only. Lab interpretation should always be confirmed by a qualified clinician.
What is the AST/ALT ratio?
The AST/ALT ratio compares two common liver enzymes in bloodwork: AST (aspartate aminotransferase) and ALT (alanine aminotransferase). This value is also known as the De Ritis ratio.
On its own, a ratio does not diagnose disease. But in context—together with your absolute enzyme levels, symptoms, medications, alcohol history, imaging, and other markers—it can help clinicians understand patterns of liver injury.
AST vs ALT: what each enzyme means
AST (Aspartate Aminotransferase)
AST is found in liver cells, but also in heart, muscle, kidneys, and red blood cells. Because it exists in multiple tissues, AST can rise for liver and non-liver reasons (for example, intense exercise or muscle injury).
ALT (Alanine Aminotransferase)
ALT is more liver-specific than AST. When ALT is elevated, clinicians often pay close attention to liver-related causes. ALT can rise in fatty liver disease, viral hepatitis, medication-related injury, and more.
Formula used in this calculator
AST/ALT ratio = AST value ÷ ALT value
Example: if AST is 60 U/L and ALT is 30 U/L, then ratio = 60 ÷ 30 = 2.0.
How to use this AST ALT ratio calculator
- Find your AST and ALT values from your lab report (same units, usually U/L).
- Enter AST in the first field and ALT in the second field.
- Click Calculate Ratio.
- Review the result and interpretation note.
General interpretation guide
| AST/ALT Ratio | Common Clinical Pattern (Generalized) |
|---|---|
| < 1.0 | Often seen when ALT is higher than AST; can occur in many conditions, including fatty liver patterns. |
| ~ 1.0 to < 2.0 | Intermediate range; interpretation depends heavily on total enzyme levels and overall clinical context. |
| ≥ 2.0 | Can be associated with alcohol-related liver injury patterns, especially with other supporting findings. |
These are broad educational ranges, not diagnostic cutoffs. A normal ratio does not guarantee normal liver health, and an abnormal ratio does not by itself prove a specific diagnosis.
Why the ratio matters
Clinicians frequently evaluate more than one liver test at once. The AST/ALT ratio can add pattern recognition to:
- Routine liver function screening
- Follow-up of elevated enzymes
- Monitoring known liver conditions over time
- Risk assessment with other scores and imaging
Important limitations
- AST can rise from muscle injury, not just liver injury.
- Recent alcohol intake may change enzyme patterns.
- Medications, supplements, and viral illnesses can affect values.
- Single-timepoint labs are less informative than trends over time.
- Age, sex, metabolic health, and lab reference intervals matter.
Frequently asked questions
Is a lower AST/ALT ratio always better?
Not always. Lower or higher ratios can each appear in different conditions. Your full lab panel and medical context are more important than the ratio alone.
Can I have a “normal” ratio with abnormal AST and ALT?
Yes. The ratio might look ordinary while both enzymes are elevated. That is why absolute AST and ALT values still matter.
Can exercise affect AST and ALT?
Strenuous exercise can increase AST (and sometimes ALT), especially when muscle breakdown is involved. Tell your clinician about recent training before testing.
Bottom line
This AST ALT ratio calculator is a quick way to compute the De Ritis ratio from your blood test numbers. Use it as a screening and education tool—not as a diagnosis. If your liver enzymes are elevated, discuss your results with a licensed healthcare professional for personalized interpretation and next steps.