Albumin-to-Creatinine Ratio (ACR) Calculator
Calculate urine ACR from albumin and creatinine concentrations and place the result in the standard A1 – A3 albuminuria categories.
Excel export is ready for the demonstration values.
Urine test values
Required. Enter a non-negative urine albumin concentration.
Required. The unit switch converts the current value rather than only changing the label.
Live result
Albumin : creatinine ratio
72.7 mg/g
Albuminuria category
A2
Interpretation
Moderately increased
Creatinine normalized
0.1100 g/dL
ACR is 72.7 mg/g, category A2, moderately increased.
Albuminuria categories
| Category | ACR band | Interpretation | Current result |
|---|---|---|---|
| A1 | < 30 mg/g | Normal to mildly increased | – |
| A2 | 30 – 300 mg/g | Moderately increased | 72.7 mg/g |
| A3 | > 300 mg/g | Severely increased | – |
How to use this ACR calculator
What this calculator does
This calculator converts two measurements from a urine sample into the urine albumin-to-creatinine ratio, usually abbreviated ACR or uACR. ACR expresses milligrams of albumin per gram of creatinine and helps correct an albumin concentration for how concentrated or dilute the urine is. It is useful for checking a lab calculation, understanding how the ratio is formed, and seeing which standard albuminuria category the result falls into. It does not diagnose chronic kidney disease by itself, replace repeat testing, or interpret an individual result in the context of symptoms, medicines, pregnancy, exercise, infection, blood pressure, diabetes, or estimated glomerular filtration rate (eGFR). The NIDDK guidance on assessing urine albumin explains why a spot urine ACR is commonly used and how the ratio adjusts for urine concentration.
When to use it
Use the calculator when you have a urine albumin result plus a urine creatinine result from the same specimen and want to reproduce the reported ACR. It is also useful when comparing two lab reports that express urine creatinine in different units, when learning the A1 – A3 albuminuria categories, or when preparing a clear record of the calculation for a discussion with a clinician.
How to calculate
- The calculator opens with a complete demonstration: Albumin is 8 mg/dL and Creatinine is 110 mg/dL. The result and a validated example Excel workbook are available immediately.
- Replace Albumin with the urine albumin concentration from your report. Use mg/dL and enter an ordinary decimal number such as 8, 8.5, or 0.4. Commas and scientific notation are intentionally rejected to avoid ambiguous input.
- Replace Creatinine with the urine creatinine concentration from the same specimen. Choose mg/dL or mmol/L from the unit control. When you switch units, the current number is converted so the physical concentration stays the same.
- Read Albumin : creatinine ratio in mg/g, then review the Albuminuria category, Interpretation, and Creatinine normalized values. The category table highlights the row containing the current result.
- Select Download Excel to export the current typed inputs and calculated outputs as an .xlsx workbook. Reset clears the demonstration data and results; while the required fields are empty, Excel export is disabled until a complete valid state is entered again.
Input guide
Albumin is required and is entered in mg/dL. Zero or a positive finite decimal is accepted; negative numbers, grouped values such as “1,000”, scientific notation, and unit text pasted into the field are rejected. A realistic example is 8 mg/dL. Holding creatinine constant, a higher albumin value increases ACR in direct proportion. A common mistake is mixing units from different reports or using serum albumin instead of urine albumin.
Creatinine is required and must be greater than zero because it is the denominator of the ratio. A realistic example is 110 mg/dL, which equals 0.1100 g/dL. The Creatinine unit control accepts mg/dL or mmol/L; this calculator uses 1 mmol/L ≈ 11.3 mg/dL for the unit conversion. With albumin fixed, a higher urine creatinine concentration lowers the ratio. A zero value is invalid because division by zero cannot produce a meaningful ACR.
Output guide
Albumin : creatinine ratio is the primary calculated result in mg/g. Albuminuria category assigns A1 when ACR is below 30 mg/g, A2 from 30 through 300 mg/g, and A3 above 300 mg/g. Interpretation gives the corresponding plain-language label: normal to mildly increased, moderately increased, or severely increased. Creatinine normalized shows the denominator in g/dL so the ratio calculation is transparent. The summary pills repeat the current ACR, category, and selected creatinine unit; they do not represent separate calculations. The table columns show Category, ACR band, Interpretation, and the Current result for the matching row. The National Kidney Foundation CKD classification page provides the A1 – A3 albuminuria thresholds together with the separate GFR categories used in CKD classification.
Worked example
With the startup values, urine albumin is 8 mg/dL and urine creatinine is 110 mg/dL. First convert creatinine to grams per deciliter: 110 mg/dL ÷ 1000 = 0.1100 g/dL. Then divide albumin by creatinine in g/dL: 8 ÷ 0.1100 = 72.727... mg/g, displayed as 72.7 mg/g. Because 72.7 lies between 30 and 300 mg/g, the calculator reports A2 and Moderately increased. These values match the first-open result, the highlighted table row, and the workbook checkpoints.
Understanding urine ACR
Albumin is a protein that is normally retained in the bloodstream, while creatinine is a waste product excreted in urine. A spot urine albumin concentration by itself can vary with hydration and urine concentration. Dividing albumin by creatinine creates a concentration-adjusted ratio that is more useful for screening and follow-up. The NIDDK overview of CKD tests and diagnosis notes that a uACR above 30 mg/g may be a sign of kidney disease and that clinicians may repeat abnormal testing to confirm the finding.
The categories in this calculator describe the degree of albuminuria. A1 is below 30 mg/g, A2 is 30 – 300 mg/g, and A3 is above 300 mg/g. Those bands are clinically useful, but ACR is a continuous measure: a value near a boundary should not be interpreted as a sudden biological change simply because the category label changes. Trends over time, repeat samples, and other kidney measurements can matter as much as a single category.
Formula, units, and practical cautions
The calculation is ACR = urine albumin in mg/dL ÷ urine creatinine in g/dL. When creatinine is reported in mg/dL, the calculator divides by 1000 to convert milligrams to grams. When creatinine is entered in mmol/L, it is first converted to mg/dL using the same approximate factor stated in the source model, then normalized to g/dL. Rounding occurs only for display; the canonical model and Excel workbook keep the full finite numeric values.
ACR can be temporarily affected by circumstances around collection, and a single result does not establish a diagnosis. Laboratories may also use different units or reporting conventions. Confirm that both measurements come from the same urine specimen and that the unit printed on the laboratory report matches the unit selected here. If a result is unexpected, very high, or inconsistent with a previous test, discuss the original laboratory report with a qualified health professional rather than relying on a stand-alone calculator.