MELD Score Calculator: How the MELD Score Is Calculated

How-to · Evergreen guide

The MELD score isn't pulled from a single test — it's calculated from a formula using three lab values. Understanding that formula makes the score far less mysterious, and it helps you see why your number changes from visit to visit.

The original MELD formula

The classic MELD equation, introduced in 2000, looks like this:

MELD = 3.78 × ln(bilirubin) + 11.2 × ln(INR) + 9.57 × ln(creatinine) + 6.43

Here, "ln" is the natural logarithm, and each lab value is in specific units:

Bilirubin in mg/dL
INR (no units)
Creatinine in mg/dL

The rules that keep the math sensible

The formula has a few built-in guardrails so it behaves predictably:

Any lab value below 1.0 is set to 1.0 (so the logarithm never goes negative).
Creatinine is capped at 4.0 mg/dL — and if the patient is on dialysis, creatinine is set to 4.0.
The final score is rounded to the nearest whole number and capped at 40.

A worked example

Say a patient has these results: bilirubin 2.0 mg/dL, INR 1.5, creatinine 1.2 mg/dL.

ln(2.0) = 0.693, ln(1.5) = 0.405, ln(1.2) = 0.182. Plugging in:

(3.78 × 0.693) + (11.2 × 0.405) + (9.57 × 0.182) + 6.43
= 2.62 + 4.54 + 1.74 + 6.43 = 15.33, rounded to 15

That gives a MELD score of about 15, which sits in the moderate range.

The MELD-Na adjustment (added in 2016)

Researchers found that low sodium (hyponatremia) is an independent sign of worse outcomes, so a sodium term was added. The MELD-Na formula is:

MELD-Na = MELD − sodium − [0.025 × MELD × (140 − sodium)] + 140

Sodium is measured in mmol/L and is bounded between 125 and 140 for the calculation. This version is what many transplant programs used from 2016 until MELD 3.0 arrived in 2023.

Score ranges at a glance

Score	Severity
6–9	Lower
10–19	Moderate
20–29	Severe
30–39	Very severe
40	Maximum (capped)

Where to get a reliable calculation

You don't need to do logarithms by hand. Official, standardized calculators are available online — most people use the OPTN calculator or the widely cited Mayo Clinic MELD calculator. These apply the correct formula and guardrails automatically.

That said, the "official" number for your care always comes from your transplant center or lab, not from a home calculation. Use an online calculator to understand your results, not to make medical decisions.

Frequently asked questions

Can I calculate my MELD score myself?

You can estimate it with the formula or an online calculator if you have your three lab values, but the number used for your care should come from your doctor, who uses standardized tools and the correct version of the score.

Why did my MELD score change even though I feel the same?

Because the score is built from lab values, small changes in bilirubin, creatinine, or INR — from an infection, a medication, or hydration — can move the number even when you feel unchanged.

What's the difference between MELD and MELD-Na?

MELD-Na is the same core score plus a sodium adjustment. Low sodium is linked to worse outcomes, so MELD-Na gives those patients a higher score. See our guide to MELD-Na vs MELD 3.0 for the full picture.

Medical disclaimer: This article is for general education only and is not medical advice. Always have your MELD score calculated and interpreted by a qualified clinician using official tools.