Fatty Liver Index (FLI) Calculator

What the Fatty Liver Index is

The Fatty Liver Index (FLI) estimates the chance that fat has built up in the liver (hepatic steatosis), the first stage of fatty liver disease (MASLD, formerly NAFLD). It was developed in Italy by Bedogni and colleagues in 2006 and uses four values you can get from a routine check-up: BMI, waist circumference, triglycerides and GGT.

The result is a number from 0 to 100. It is calculated with this formula, where ln is the natural logarithm:

y = 0.953 × ln(triglycerides) + 0.139 × BMI + 0.718 × ln(GGT) + 0.053 × waist − 15.745
FLI = ey ÷ (1 + ey) × 100

Units to use

• Triglycerides in mg/dL. If your report shows mmol/L, multiply by 88.5 (for example 1.9 mmol/L ≈ 168 mg/dL).
• GGT in U/L (IU/L is the same).
• Waist in cm, measured at the level of the belly button while standing and breathing out normally.
• BMI in kg/m². Work it out with the BMI Calculator if you need to.

How the result is read

• Below 30: fatty liver is unlikely (the original study used this to rule it out).
• 30 to 59: indeterminate.
• 60 or higher: fatty liver is likely (the study used this to rule it in).

Limits

• FLI shows whether fat is likely to be present, not how much scarring (fibrosis) there is. Scarring is what matters most for long-term liver health; the FIB-4 calculator estimates that.
• GGT also rises with alcohol and some medicines, and triglycerides change after a meal, so use fasting results where possible.
• The index was built on an adult European population. It may be less accurate in other groups.

Educational estimate only. Please discuss your result with your doctor.