MELD Score Calculator
Three Numbers, One Score
The MELD score began life in 2001 as a tool for predicting survival after a specific liver procedure, and was rapidly repurposed into something far more consequential: a way to rank candidates for liver transplantation by medical urgency rather than by waiting time. It condenses three routine laboratory values — bilirubin, INR and creatinine — into a single integer between 6 and 40. This calculator implements the original 2002 formulation.
The Formula
Any value below 1.0 is set to 1.0
Creatinine is capped at 4.0, or set to 4.0 if on dialysis
The result is rounded and clamped to the range 6–40
The natural logarithms are the heart of it. They compress the top of each lab range so that a bilirubin moving from 20 to 25 shifts the score far less than a move from 2 to 7 does. The 1.0 floor exists to stop normal or low values from contributing negative terms — ln(1.0) is exactly zero, which is why a patient with all three values at or below 1.0 lands on the floor score of 6, from the constant 6.43 alone.
Worked Examples
Each row was computed with the formula above, including the flooring, capping and clamping steps:
| Bilirubin (mg/dL) | INR | Creatinine (mg/dL) | MELD |
|---|---|---|---|
| 1.0 | 1.0 | 1.0 | 6 |
| 2.0 | 1.3 | 1.2 | 14 |
| 4.0 | 1.8 | 1.5 | 22 |
| 8.0 | 2.5 | 2.5 | 33 |
| 15.0 | 3.0 | 3.5 | 40 |
The first row is the arithmetic floor: with every input at 1.0, all three logarithmic terms vanish and only the 6.43 constant survives, rounding to 6.
Why Each Input Is There
| Input | Coefficient | What it reflects |
|---|---|---|
| Bilirubin | 3.78 | The liver's capacity to clear and excrete bile pigment |
| INR | 11.2 | Synthetic function — the liver manufactures clotting factors |
| Creatinine | 9.57 | Kidney function, which deteriorates alongside advanced liver disease |
The largest coefficient sits on INR, which is worth pausing over. INR moves over a narrow numeric range compared with bilirubin, so a large multiplier is needed for it to carry comparable weight. Coefficient size reflects scaling as much as it reflects importance.
The Dialysis Rule
Setting creatinine to 4.0 for a dialysed patient is a deliberate correction rather than an approximation. Dialysis artificially lowers measured creatinine, so a patient in renal failure could otherwise post a deceptively reassuring value precisely because they are being treated for the problem the score is trying to detect. Fixing the input at the cap prevents the treatment from masking the severity.
Where the Score Is Used
- Transplant allocation — MELD and its later variants underpin how liver waiting lists are prioritised in several national systems.
- Prognostic discussion — the score gives clinicians a shared, quantitative vocabulary for disease severity.
- Procedural risk — it is frequently referenced when weighing surgery in patients with cirrhosis.
- Tracking trajectory — a score that climbs across serial measurements says more than any single value.
How to Use This Calculator
- Enter Bilirubin (mg/dL) — total bilirubin from a standard liver panel.
- Enter INR, the international normalised ratio from coagulation testing.
- Enter Creatinine (mg/dL).
- Choose Not on Dialysis or On Dialysis (2+ times in past week) — selecting dialysis overrides the creatinine you entered and fixes it at 4.0.
- Select Calculate. The output traces every adjustment, so you can see exactly which values were floored, capped or clamped before the logarithms were taken.
Related Calculations
Creatinine drives one of the three MELD terms — explore it directly with the eGFR Calculator or the Creatinine Clearance Calculator.