Albumin Creatinine Ratio Calculator

Convert a spot urine albumin and creatinine into the albumin-to-creatinine ratio (ACR) in mg/g and mg/mmol, with the KDIGO albuminuria category.

Quick Facts

Formula
ACR (mg/g) = albumin / creatinine x 1000
Both in mg/dL. Divide mg/g by 8.84 for mg/mmol.
KDIGO bands
A1 <30, A2 30-300, A3 >300 mg/g
A2 and A3 were formerly micro- and macroalbuminuria.

Your Results

Calculated
ACR (mg/g)
-
Albumin-to-creatinine ratio
ACR (mg/mmol)
-
SI units (mg/g / 8.84)
KDIGO stage
-
A1, A2, or A3
Category
-
Albuminuria level

Ready

Enter a urine albumin and creatinine, then press Calculate.

About the Albumin Creatinine Ratio

The urine albumin-to-creatinine ratio (ACR, or UACR) estimates how much albumin your kidneys leak into the urine, using a single "spot" sample instead of a 24-hour collection. Because a spot sample can be dilute or concentrated depending on how much you have had to drink, dividing the albumin concentration by the creatinine concentration corrects for that. Creatinine is excreted at a fairly steady rate, so the ratio approximates the daily albumin loss without a timed collection.

The formula

When urine albumin and urine creatinine are both reported in milligrams per deciliter (mg/dL), the ratio in milligrams per gram is:

  • ACR (mg/g) = (urine albumin in mg/dL / urine creatinine in mg/dL) x 1000. The factor of 1000 converts "mg albumin per mg creatinine" into "mg albumin per gram of creatinine."
  • ACR (mg/mmol) = ACR (mg/g) / 8.84. Many countries report the ratio in SI units; 8.84 is the number of millimoles in one gram of creatinine (molar mass 113.12 g/mol).
  • If albumin is reported in mg/L instead of mg/dL, this calculator divides it by 10 first (10 mg/L = 1 mg/dL) before applying the formula.

Interpreting the result (KDIGO categories)

Kidney guidelines group the ratio into three albuminuria categories. These are population reference bands, not a diagnosis:

  • A1 - Normal to mildly increased: below 30 mg/g (about 3 mg/mmol).
  • A2 - Moderately increased: 30 to 300 mg/g (about 3 to 30 mg/mmol). This range was previously called microalbuminuria.
  • A3 - Severely increased: above 300 mg/g (about 30 mg/mmol). Previously called macroalbuminuria.

When to consult a professional

A single raised ratio can be caused by strenuous exercise, fever, urinary infection, high blood sugar, or menstrual contamination, so an abnormal result is usually confirmed with two or three early-morning samples over a few weeks. This calculator performs the arithmetic only and does not diagnose kidney disease or guide treatment. Discuss any result that concerns you, and any decision about medication, with a licensed healthcare provider.

Frequently Asked Questions

How is the albumin-to-creatinine ratio calculated?
With urine albumin and urine creatinine both in mg/dL, ACR in mg/g equals (albumin / creatinine) x 1000. For example, 2 mg/dL albumin and 120 mg/dL creatinine give (2 / 120) x 1000 = 16.7 mg/g. Divide the mg/g value by 8.84 to get mg/mmol.
What ACR level is considered normal?
Under the KDIGO albuminuria categories, below 30 mg/g (about 3 mg/mmol) is A1, normal to mildly increased. A2 is 30 to 300 mg/g (moderately increased, formerly microalbuminuria) and A3 is above 300 mg/g (severely increased, formerly macroalbuminuria).
Why use the ratio instead of urine albumin alone?
A spot urine sample can be dilute or concentrated depending on fluid intake. Dividing by creatinine, which is excreted at a fairly steady rate, corrects for that concentration so a random sample approximates a 24-hour albumin measurement without a timed collection.
Should a single high ACR result be treated as a diagnosis?
No. A raised ratio can result from exercise, fever, infection, or menstrual contamination. Guidelines suggest confirming an abnormal result with two or three early-morning samples over several weeks. Discuss any elevated result with a licensed healthcare provider.

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