Albumin Creatinine Ratio Calculator (urine ACR, mg/g and mg/mmol, KDIGO A1–A3)

Understanding the albumin creatinine ratio calculator — concept and principle

This calculator works out the urine albumin-to-creatinine ratio (ACR) from a spot urine sample, in mg/g and mg/mmol, and places it in the KDIGO albuminuria categories A1 to A3. People with diabetes or high blood pressure checking kidney results, and students, use it.

Albumin per gram of creatinine — with the default inputs: 37.5 mg/g.

How it is calculated

Creatinine to g/L: mg/dL × 0.01, or mmol/L × 0.11312 (molar mass 113.12 g/mol)
Albumin in mg/dL × 10 = mg/L
ACR (mg/g) = urine albumin (mg/L) ÷ urine creatinine (g/L)
ACR (mg/mmol) = mg/g ÷ 8.84
KDIGO: A1 under 30 mg/g (under 3 mg/mmol); A2 30–300 mg/g (3–30 mg/mmol); A3 300 mg/g or more

The principle

Healthy kidneys let very little albumin into the urine, so albumin in urine is an early sign of kidney damage. A single urine sample can be dilute or concentrated, which changes the albumin concentration. Creatinine is excreted at a fairly steady rate, so dividing albumin by creatinine corrects for concentration and approximates the daily albumin loss. KDIGO uses albuminuria categories alongside kidney function (GFR) to describe chronic kidney disease.

Worked example

Defaults: urine albumin 45 mg/L; urine creatinine 120 mg/dL.

Creatinine = 120 × 0.01 = 1.2 g/L; albumin 45 mg/L.
ACR = 45 ÷ 1.2 = 37.5 mg/g.
In mg/mmol = 37.5 ÷ 8.84 = 4.2.
30–300 mg/g: Category A2, Moderately increased.

Each point is the calculator re-run with only “Urine creatinine” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Urine creatinine	Albumin/creatinine ratio (mg/g)
30	150
60	75
90	50
120	37.5
150	30
180	25
240	18.8

How to read the result

Where does your result fall?

A result in A2 or A3 should be confirmed, because exercise, fever, infection, menstruation and very high blood sugar can raise a single result. KDIGO asks for raised values to be repeated; chronic kidney disease requires abnormalities lasting more than three months. Your doctor interprets ACR together with eGFR, blood pressure and other findings.

Common mistakes

Using albumin and creatinine from different samples.
Mixing mg/g and mg/mmol thresholds.
Testing after heavy exercise or during an infection.
Treating one raised result as a diagnosis.

Keep in mind: Not a diagnosis. Discuss results with your doctor, who will decide on repeat testing and treatment.

Frequently asked questions

What is a normal urine ACR?

Under 30 mg/g (under 3 mg/mmol) is category A1.

Why use a ratio instead of albumin alone?

The ratio corrects for how concentrated the urine sample is.

How many mg/g is 3 mg/mmol?

About 26.5 mg/g; KDIGO rounds the category boundary to 30 mg/g.

Sources: KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney Int Suppl 2013;3(1)

Checked 9 Nov 2026. KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney Int Suppl 2013;3(1) — albuminuria categories A1–A3 (AER and ACR in mg/mmol and mg/g); creatinine molar mass 113.12 g/mol.

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