How the Albumin Creatinine Ratio Calculator works
Healthy kidneys let very little albumin (a blood protein) pass into urine. The urine albumin-to-creatinine ratio (ACR) compares the albumin concentration with the creatinine concentration in the same spot sample. Dividing by creatinine corrects for how concentrated or dilute the urine is, so a random sample can approximate daily albumin excretion.
ACR is recommended for detecting kidney damage — particularly in people with diabetes or high blood pressure — and is used with eGFR to classify CKD.
Supported units
- Albumin: mg/L, mg/dL (× 10 = mg/L), µg/mL (= mg/L)
- Creatinine: mg/dL, µmol/L (÷ 88.4 = mg/dL), mmol/L (× 1000 ÷ 88.4 = mg/dL)
Formula used
ACR (mg/g) = urine albumin (mg/L) ÷ urine creatinine (g/L)
ACR (mg/mmol) = urine albumin (mg/L) ÷ urine creatinine (mmol/L)
ACR (mg/mmol) = urine albumin (mg/L) ÷ urine creatinine (mmol/L)
- Creatinine mg/dL × 0.01 = g/L
- Creatinine mg/dL × 88.4 ÷ 1000 = mmol/L
- Approximate conversion: ACR mg/g × 0.113 ≈ mg/mmol
Worked example
Urine albumin 30 mg/L and urine creatinine 100 mg/dL:
- Creatinine = 100 × 0.01 = 1.0 g/L → ACR = 30 ÷ 1.0 = 30 mg/g
- Creatinine = 100 × 88.4 ÷ 1000 = 8.84 mmol/L → ACR = 30 ÷ 8.84 ≈ 3.4 mg/mmol
Interpreting the result
KDIGO albuminuria categories (educational):
| Category | ACR (mg/g) | ACR (mg/mmol) | KDIGO description |
|---|---|---|---|
| A1 | < 30 | < 3 | Normal to mildly increased |
| A2 | 30–300 | 3–30 | Moderately increased |
| A3 | > 300 | > 30 | Severely increased |
An increased ACR should be confirmed on repeat testing — commonly 2 of 3 samples over 3–6 months — before it is considered persistent.
Limitations
- Exercise, fever, infection (including urinary tract infection), menstruation, very high blood glucose or blood pressure can temporarily raise ACR.
- First-morning samples are preferred because albumin excretion varies through the day.
- Very low muscle mass lowers urine creatinine and can make ACR appear higher.
- Laboratory methods and reporting units vary; a single value cannot diagnose kidney disease.
Frequently asked questions
It compares the amount of albumin with the amount of creatinine in a urine sample, giving an estimate of albumin leakage that is corrected for urine concentration.
No. They are different units. Multiply mg/g by about 0.113 to get mg/mmol — for example, 30 mg/g ≈ 3.4 mg/mmol.
ACR measures albumin only, while UPCR measures total urine protein (albumin plus other proteins). ACR is more sensitive for early kidney damage.
ACR varies from day to day and can rise temporarily with exercise, infection or fever. Guidelines recommend confirming an increased result on repeat samples.
The older term microalbuminuria roughly corresponds to the KDIGO A2 category (30–300 mg/g). Current guidelines prefer the terms "moderately increased" or "severely increased" albuminuria.
Medical disclaimer:
This calculator is intended for educational and informational purposes and does not replace professional medical advice, diagnosis, laboratory interpretation, or treatment.
Laboratory methods and reference intervals vary. Always consult a qualified healthcare professional about your results.