Albumin Creatinine Ratio Calculator

What the albumin-creatinine ratio measures

A spot urine albumin-creatinine ratio (ACR) divides urine albumin by urine creatinine.

Reporting albumin per gram of creatinine adjusts for how dilute or concentrated that void is. You do not need a 24-hour jug to screen for albuminuria. KDIGO categories are A1 below 30 mg/g (normal to mildly increased), A2 from 30 to 299 mg/g (moderately increased), and A3 at 300 mg/g or higher (severely increased). In SI units those bands are below 3, 3 to 29, and 30 or more mg/mmol, with rounded conversions.

Albuminuria is kidney damage. It can exist while eGFR is still G1 or G2. NIDDK and KDIGO treat ACR as a partner to eGFR in people with diabetes, hypertension, or other CKD risk.

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Formula and unit conversions

When both albumin and creatinine are in mg/dL, ACR (mg/g) = (albumin ÷ creatinine) × 1000. The factor of 1000 turns the ratio into milligrams of albumin per gram of creatinine.

If albumin is printed in mg/L, divide by 10 to get mg/dL (10 mg/L = 1 mg/dL). If creatinine is in µmol/L, divide by 88.4. The unit menus do those conversions.

Example: albumin 1.5 mg/dL, creatinine 100 mg/dL. ACR = 1.5/100 × 1000 = 15 mg/g (A1). Fifteen is not “zero albumin.” It sits in the normal-to-mild band.

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How to use the ACR calculator

Use laboratory urine albumin and urine creatinine from the same void, preferably first-morning. Enter each value with the unit on the report. Read mg/g and the A category together.

Do not diagnose CKD from one elevated ACR. Confirm persistence over three months unless the picture is already an obvious nephrotic presentation. Repeat after treating a urine infection.

If the result will start a talk about an ACE inhibitor, ARB, SGLT2 inhibitor, or mineralocorticoid-receptor antagonist, bring the laboratory report. This page does not recommend drugs.

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How to collect the sample

A random spot urine is acceptable for screening.

First-morning urine reduces orthostatic albuminuria in some young people. Midstream collection reduces contamination. Skip the test right after fever, marked hyperglycemia, or a long run. Those states can raise albumin for a day. Menstruation and vaginal discharge contaminate the measurement. Recollect when the confounder is gone.

A protein dipstick is not a substitute when you need A1 versus A2. Dipsticks are semi-quantitative for total protein and miss many A2 results.

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Persistence, CGA staging, and next steps

CKD staging needs cause, GFR category, and albuminuria category.

An eGFR of 92 with ACR 420 mg/g on two occasions three months apart is CKD G1 A3, not “normal kidneys because GFR is 90.” Cardiovascular and kidney-failure risk rise across A categories even when G stays high. ADA and KDIGO use ACR for annual screening in type 2 diabetes and in type 1 after five years, earlier if other risk is present. Hypertension guidelines use albuminuria to refine risk.

Two of three samples in the A2 or A3 range over 3 to 6 months is a common confirmation rule when the person is stable. If the first ACR is 42 mg/g after a 10 km race and the next first-morning sample is 12, believe the second. If three samples are 80, 110, and 95, that is persistent A2 even if eGFR remains 88. SGLT2 inhibitors, ACE inhibitors, ARBs, and finerenone can lower ACR. A falling ACR on those drugs is often the treatment working. A rising ACR despite them is a reason to look for progression, NSAID use, or another diagnosis, not a reason to average the new value with last year’s number. A3 with edema, low serum albumin, and high lipids raises a nephrotic-range question. That pattern needs timely nephrology, not another home conversion.

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What raises or lowers a single ACR

Exercise, fever, urinary infection, uncontrolled glucose, heart-failure decompensation, and hematuria can raise ACR.

ACE inhibitors and ARBs can lower ACR as part of their benefit. A drop after starting those drugs is often the intended effect, not proof last month’s lab was wrong. Very low urine creatinine (muscle wasting) inflates ACR because creatinine is the denominator. Very high urine creatinine (high muscle, concentrated overnight sample) can lower it. Categories use bands rather than a single milligram.

Protein-creatinine ratio (PCR) is a different test. KDIGO publishes parallel PCR bands (A1 below about 150 mg/g protein). Do not enter total protein here.

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Interpreting A1, A2, and A3

A1 is the usual adult range and does not by itself define CKD.

It does not guarantee healthy glomeruli if sediment, imaging, or eGFR say otherwise. A2 is moderately increased albuminuria, formerly called microalbuminuria. In diabetes it is a signal to tighten glucose and blood pressure care and to review kidney-protective therapy. Confirm with a repeat sample.

A3 includes nephrotic-range albuminuria at the high end (ACR often above about 2200 mg/g in conversion tables). Edema, thrombosis risk, and infection risk belong in that evaluation.

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SI units and rounding

An ACR of 3.4 mg/mmol is about 30 mg/g (3.4 × 8.84 ≈ 30). Laboratories round.

A result of 2.9 mg/mmol should not be fought as “not yet A2” if a repeat is 3.2. Treat values near 30 mg/g as a band that needs confirmation. If albumin is 30 mg/L and creatinine is 8 mmol/L, convert albumin to 3.0 mg/dL and creatinine to 8 × 11.3 ≈ 90.4 mg/dL (mmol/L creatinine × 11.3 ≈ mg/dL). ACR ≈ 3.0/90.4 × 1000 = 33 mg/g. Entering 30 and 8 without converting units invents a nonsense ratio.

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Limitations

The conversion between mg/g and mg/mmol uses 8.84 and is rounded in published tables. Do not argue 29 versus 30 mg/g from calculator rounding. Repeat the laboratory test.

Point-of-care ACR devices need validation. This page assumes laboratory concentrations. Children, pregnancy, and orthostatic proteinuria need age-specific reading. This tool uses adult KDIGO A categories. Orthostatic proteinuria is a benign pattern in some adolescents: ACR is higher while upright and near A1 on a first-morning sample. Prefer a morning sample before labeling a young person as A2 CKD.

Race, sex, and muscle mass change creatinine excretion and therefore the ACR denominator. Categories are population bands, not personalized biologic cutoffs. A muscular young man and a sarcopenic older woman with the same albumin excretion can print different ACRs. When the question is nephrotic-range leak, 24-hour albumin or a PCR can add information. Contrast dye, NSAIDs, and volume depletion can change GFR without an immediate ACR change. Do not use a same-day ACR to decide whether a creatinine bump was “just dehydration.” Repeat both markers after the acute insult settles. Home cups without a matching creatinine are albumin concentrations, not ratios. A dilute 2 mg/dL albumin can still be A2 if creatinine is also very low. Pair the two concentrations.

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How it works

ACR (mg/g) = (urine albumin in mg/dL ÷ urine creatinine in mg/dL) × 1000. mg/L albumin is divided by 10 to reach mg/dL. µmol/L creatinine is divided by 88.4 to reach mg/dL. mg/mmol ≈ mg/g ÷ 8.84.

Frequently asked questions

• Is a single high ACR enough for CKD?KDIGO classification uses persistence over three months. Fever, hard exercise, urinary infection, and menstruation can raise a one-time result.
• Why not use a dipstick alone?Dipsticks estimate protein, not quantified albumin, and miss moderate albuminuria. Laboratory ACR is the preferred albuminuria test in KDIGO and NIDDK materials.
• How does ACR relate to 24-hour albumin?An ACR of 30 mg/g roughly corresponds to 30 mg/day, and 300 mg/g to 300 mg/day, with rounding in conversion tables. The spot ratio is used because 24-hour collections are often incomplete.

Related calculators

References

1. NCBI / Diabetes in America. Albuminuria categories according to KDIGO
2. KDIGO. KDIGO 2024 CKD Guideline
3. NIDDK. Estimated GFR calculators (albuminuria recommendation)
4. NIDDK. Albuminuria: Albumin in the Urine
5. NIDDK. Laboratory evaluation of kidney disease
6. American Diabetes Association. Standards of Care in Diabetes
7. NIDDK. About Chronic Kidney Disease