ACR Calculator
A urine albumin of 2 mg/dL with a urine creatinine of 100 mg/dL gives an ACR of 20 mg/g, in the normal to mildly increased range. This ACR calculator computes the urine albumin-to-creatinine ratio from a urine albumin value and a urine creatinine value, then reports the result in mg/g using common published cutoffs. Enter each value as it appears on your urine test and match the unit selector to your lab report.
Quick answer
ACR (mg/g) equals urine albumin in mg/dL times 1000, divided by urine creatinine in mg/dL.
What this tells you
- •ACR (mg/g) equals urine albumin in mg/dL times 1000, divided by urine creatinine in mg/dL.
- •This tool accepts urine albumin in mg/dL or mg/L and urine creatinine in mg/dL or g/L, then converts both to mg/dL before dividing.
- •The result is grouped into normal to mildly increased, moderately increased, or severely increased bands using common published cutoffs.
- •A single spot ACR is a screening estimate, not a diagnosis of kidney disease.
How to Use
- 1Enter your urine albumin value and select whether it is in mg/dL or mg/L.
- 2Enter your urine creatinine value and select whether it is in mg/dL or g/L.
- 3Calculate to see the ACR in mg/g and its interpretation band.
- 4Compare the result with your lab reference range, since a single spot sample can vary from day to day.
How It Works
Formula
ACR (mg/g) = (urine albumin in mg/dL x 1000) / urine creatinine in mg/dL
mg/L albumin converts to mg/dL by dividing by 10
g/L creatinine converts to mg/dL by multiplying by 100
Example: (2 mg/dL x 1000) / 100 mg/dL = 20 mg/gThe calculator first converts both inputs to mg/dL using standard concentration conversions. It then multiplies the urine albumin concentration by 1000 and divides by the urine creatinine concentration, which produces a result in the milligrams of albumin per gram of creatinine unit used on most lab reports and in common kidney health guidelines.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Normal-range example in mg/dL
2 mg/dL times 1000, divided by 100 mg/dL, equals 20 mg/g, below the 30 mg/g cutoff.
Moderately increased example with mixed units
150 mg/L converts to 15 mg/dL and 1 g/L converts to 100 mg/dL, so 15 mg/dL times 1000, divided by 100 mg/dL, equals 150 mg/g.
Common ACR Interpretation Bands
These published albuminuria categories are used alongside eGFR for kidney health screening.
| Category | ACR range | What it generally suggests |
|---|---|---|
| Normal to mildly increased (A1) | Below 30 mg/g | Generally considered within the normal screening range |
| Moderately increased (A2) | 30 to 300 mg/g | May indicate early kidney changes and often prompts a repeat test |
| Severely increased (A3) | Above 300 mg/g | Associated with a higher likelihood of kidney damage and usually needs clinical follow-up |
A clinician interprets ACR together with eGFR and other test results, not as a stand-alone diagnosis.
How to interpret a calculated ACR
The two concentrations must come from the same urine sample. Creatinine helps adjust albumin for how concentrated or dilute that sample is. The ratio does not measure blood creatinine or directly calculate filtration. Do not combine a urine albumin result from one date with urine creatinine from another collection.
Unit matching is essential. Albumin in mg/L is divided by 10 to obtain mg/dL. Creatinine in g/L is multiplied by 100 to obtain mg/dL. The formula then multiplies albumin by 1,000 because the reported denominator is grams of creatinine. A lab that already reports UACR or ACR in mg/g has completed this calculation, so its reported result should normally take priority over re-entering rounded components.
The implementation labels values below 30 mg/g as A1, values from 30 through 300 mg/g as A2, and values above 300 mg/g as A3. These categories describe albuminuria severity under a common framework. They do not by themselves establish chronic kidney disease, its cause, its stage, or the need for a particular medicine.
Persistence matters clinically. Albumin excretion can vary between samples, and clinicians may repeat an abnormal result under suitable conditions. Exercise, fever, infection, urinary bleeding, menstruation, marked hyperglycemia, blood-pressure changes, dehydration, and acute illness can affect a sample. Timing and collection instructions from the laboratory or clinician should be followed.
Laboratories use assays with detection limits and measurement uncertainty. A value reported as less than a threshold is not the same as an exact number at that threshold. This calculator cannot accept inequality signs or assay flags. Do not replace a less-than result with an invented value solely to force a ratio.
Clinical kidney assessment commonly considers ACR with estimated glomerular filtration rate, blood pressure, diabetes status, medicines, symptoms, age, and repeated results. Population, pregnancy, acute kidney injury, dialysis, transplantation, and pediatric care can require different interpretation. Use the reference and follow-up instructions attached to the actual report.
A result at a category boundary should not be treated as a sharp biological divide. Measurement variation can place nearby samples on either side. The calculator rounds ACR to one decimal, albumin to two decimals, and creatinine to one decimal after using the converted values. Clinical decisions should use the laboratory data and professional interpretation, not the displayed band alone.
Common mistakes
- Entering urine creatinine as zero or leaving it blank, which makes the ratio undefined.
- Pasting a mg/L albumin value into the field without switching the unit selector to mg/L.
- Treating a single high spot ACR as a confirmed diagnosis instead of a screening signal that often needs a repeat test.
- Combining albumin and creatinine values from different urine collections.
- Assuming the category alone gives kidney function without reviewing eGFR and clinical history.
- Ignoring the laboratory's own reporting limit, assay notes, or reference information.
Limitations
This calculator assumes albumin and creatinine come from the same urine sample. It accepts albumin only in mg/dL or mg/L and creatinine only in mg/dL or g/L. It cannot process less-than signs, assay detection limits, 24-hour excretion, timed collections, blood values, or a laboratory's quality flags. The A1, A2, and A3 bands are screening categories, not a diagnosis. Exercise, fever, infection, urinary bleeding, menstruation, hydration, acute illness, blood pressure, glucose, pregnancy, medicines, and collection timing can affect results. The tool does not calculate eGFR or account for persistence, age-specific care, pediatrics, dialysis, transplant status, or assay-specific interpretation.
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