Creatinine Unit Converter: mg/dL, µmol/L and mmol/L

To convert creatinine from µmol/L to mg/dL, divide by 88.4. To convert mg/dL to µmol/L, multiply by 88.4. For example, 133 µmol/L ÷ 88.4 = 1.50 mg/dL, and 1.5 mg/dL × 88.4 = 132.6 µmol/L (about 133). For mmol/L, divide the µmol/L value by 1000: 133 µmol/L = 0.133 mmol/L.

The United States reports serum creatinine in mg/dL. Most other countries use the SI unit µmol/L, and a few reports use mmol/L. The numbers describe the same amount of creatinine in the blood, and only the measurement scale differs.

Creatinine Conversion Formulas

• mg/dL = µmol/L ÷ 88.4 (for example, 106 µmol/L ÷ 88.4 = 1.20 mg/dL)
• µmol/L = mg/dL × 88.4 (for example, 1.2 mg/dL × 88.4 = 106.1 µmol/L)
• mmol/L = µmol/L ÷ 1000, which is the same as mg/dL × 0.0884 (1.0 mg/dL = 0.0884 mmol/L)
• mg/dL = mmol/L × 1000 ÷ 88.4 (0.1 mmol/L = 100 µmol/L = 1.13 mg/dL)

Creatinine Conversion Chart: mg/dL to µmol/L and mmol/L

Each row multiplies the mg/dL value by 88.4. µmol/L is rounded to the nearest whole number and mmol/L to three decimals.

Reverse Chart: µmol/L to mg/dL

Each row divides the µmol/L value by 88.4. mg/dL is rounded to two decimals, which is finer than most labs report, so round again to one decimal if your report does.

mg/dL, µmol/L and mmol/L: What Each Unit Means

mg/dL (milligrams per decilitre) is a mass concentration: how many milligrams of creatinine sit in one tenth of a litre of blood. It is the conventional unit in the United States, and the unit the Cockcroft-Gault and eGFR equations are written in.

µmol/L (micromoles per litre) is the SI unit used by most laboratories outside the United States, including the UK, Europe and Australia. It counts creatinine molecules rather than their mass. One micromole is one millionth of a mole.

mmol/L (millimoles per litre) is the same SI unit scaled up by 1000: 1 mmol/L = 1000 µmol/L. Because serum creatinine is present in such small amounts, a serum value in mmol/L is a small decimal, about 0.09 mmol/L for 1.0 mg/dL. Urine creatinine, which is far more concentrated, is often reported in mmol/L, which is why a urine albumin/creatinine ratio may be given in mg/mmol.

The risk with mmol/L is a 1000-fold slip. A serum creatinine of 0.106 mmol/L and 106 µmol/L are the same result; reading 0.106 as mg/dL would be a serious error. If a value looks implausible for its unit, check the unit on the report before you convert.

Why the Conversion Factor Is 88.4

The constant 88.4 derives from the molar mass of creatinine, about 113.12 g/mol, together with the step from decilitres to litres: 1 mg/dL is 10 mg/L, and 10 mg divided by 113.12 mg per millimole is 0.0884 mmol, or 88.4 µmol. Because it reflects a fixed chemical property of the molecule, the factor is the same everywhere and never needs updating.

Worked Example

Suppose a lab in Europe reports a serum creatinine of 106 µmol/L and you need it in mg/dL for the Cockcroft-Gault equation. Divide by 88.4: 106 ÷ 88.4 = 1.2 mg/dL. Going the other way, a US value of 0.9 mg/dL becomes 0.9 × 88.4 = 79.6 µmol/L. The figure worth memorising is that 1.0 mg/dL equals exactly 88.4 µmol/L.

Normal Ranges in Each Unit

Typical adult reference ranges are roughly 0.7 to 1.3 mg/dL (about 62 to 115 µmol/L, or 0.062 to 0.115 mmol/L) for men and 0.6 to 1.1 mg/dL (about 53 to 97 µmol/L) for women. Every laboratory sets its own range by assay and population. A high creatinine suggests reduced kidney filtration; see high creatinine for what raised values mean.

Why Units Matter for the Calculator

The Cockcroft-Gault creatinine clearance equation expects creatinine in mg/dL. Feeding it a µmol/L value without converting inflates the denominator roughly 88-fold and produces a near-zero clearance: a classic and dangerous unit error. Convert first, or select your unit in the calculator above, which accepts either and converts internally. The same caution applies to the eGFR equations, which are also written for mg/dL.

CrCl and GFR Units

Creatinine clearance and eGFR look alike but carry different units. A Cockcroft-Gault creatinine clearance is reported in mL/min: an absolute rate for the individual patient, scaled by body weight. An eGFR from CKD-EPI or MDRD is reported in mL/min/1.73 m²: the rate indexed to a standard body surface area of 1.73 m². That indexing lets kidney function be compared and staged across people of different sizes. The FDA 2024 renal impairment guidance draws the same line, describing eGFR as commonly referenced to 1.73 m² and estimated creatinine clearance as a value in mL/min.

Because the units differ, a CrCl of 45 mL/min and an eGFR of 45 mL/min/1.73 m² are not the same measurement, and one cannot stand in for the other against a drug label threshold without thought. When an indexed eGFR is needed in absolute terms for dosing, the National Kidney Foundation describes dividing it by 1.73 and multiplying by the patient's body surface area to give mL/min. The GFR unit converter handles that step in either direction, and CrCl vs eGFR explains when each measure applies.

Where the Two Units Come From

The split is historical and geographic. The United States, alongside a few other countries, kept the older conventional mass-concentration unit, which reports how many milligrams of creatinine sit in a decilitre (one-tenth of a litre) of blood. Most of the world adopted the SI (Système International) convention, which reports concentration in moles per litre. Creatinine uses micromoles per litre because it is present in tiny amounts. Moles count molecules rather than mass, so the SI figure ties directly to the number of creatinine molecules present. Neither system is more correct. Both describe the same quantity, and the factor of 88.4 converts between them.

This matters in practice because medical literature, drug labels, and online calculators do not agree on a single unit. A guideline written in the United Kingdom may quote a creatinine threshold in µmol/L while a US drug label quotes the same threshold in mg/dL. Recognising which unit a source uses, and converting before you compare, prevents the most common and most dangerous arithmetic mistake in kidney calculations.

A Second Worked Example

A patient's chart from an overseas hospital lists a creatinine of 176.8 µmol/L. To use it in a US-based calculator, divide by 88.4: 176.8 ÷ 88.4 = 2.0 mg/dL exactly. That value is clearly elevated and would prompt an estimate of kidney function. Going the other direction, a US chart showing 0.6 mg/dL converts to 0.6 × 88.4 = 53 µmol/L, the low end of normal. Because 88.4 is exact, these conversions introduce no error of their own; any uncertainty comes from the original measurement, not the arithmetic.

How to Read a Converted Value

Once converted, the number means exactly what it would have meant in its native unit. A creatinine of 1.0 mg/dL (88.4 µmol/L) sits comfortably mid-range for most adults. A value of 1.5 mg/dL (about 133 µmol/L) is mildly raised and usually prompts an estimate of kidney function. A value of 3.0 mg/dL (about 265 µmol/L) is clearly elevated and points to substantially reduced filtration. The conversion does not change that interpretation: it only lets you place the value against whichever reference range your lab reports. Creatinine also depends on muscle mass. A muscular person and a frail person with the same true kidney function will not show the same creatinine, which is one reason a clearance estimate is more informative than the raw value.

Practical Conversion Tips

• To go from US to SI, multiply by 88.4 (roughly ×90 for a quick mental estimate).
• To go from SI to US, divide by 88.4 (roughly ÷90 for a quick mental estimate).
• Anchor on 1.0 mg/dL = 88.4 µmol/L; scale up or down from there.
• When in doubt, let the calculator do it: pick your unit and it converts internally before applying the equation.

Converting Creatinine for Protocol or Label Checks

Trial protocols and drug labels often state a creatinine or clearance limit in one unit while the laboratory reports in the other. The factor does not change: 1 mg/dL = 88.4 µmol/L. SWOG Policy 38, for example, sets a minimum serum creatinine of 0.7 mg/dL for its Cockcroft-Gault calculation, which is about 62 µmol/L (0.7 × 88.4 = 61.9). Weight limits may need converting too: 1 kg = 2.20462 lb, so divide a weight in pounds by 2.20462 to get kilograms.

A few habits keep these checks traceable:

• Record the original value and unit exactly as the laboratory reported them, next to the converted value.
• Note the factor used (88.4 for creatinine, 2.20462 for pounds to kilograms) and the direction of the conversion.
• Check plausibility: a typical adult serum creatinine sits between about 0.6 and 1.3 mg/dL, or about 53 and 115 µmol/L. A value labelled mg/dL that reads like 90, or a value labelled µmol/L that reads like 1.1, almost certainly carries the wrong unit.
• Round only at the end, after converting, so that a value close to a cutoff is not pushed across it by an early rounding step.

In a clinical trial, investigators must keep adequate and accurate case histories that record the observations and data pertinent to the study for each participant. Writing down the source value, the unit, and the factor lets an eligibility decision be checked later. For how creatinine clearance is used to screen patients for studies, see CrCl for clinical trial eligibility.

Limitations and Notes

• µmol/L is the SI (Système International) unit; mg/dL is a conventional mass-concentration unit. The conversion changes only the unit, never the underlying physiology.
• Rounding to one or two decimal places is fine for clinical use; the charts above are rounded for readability, so round only once, at the end.
• This converter handles serum creatinine only. Urine creatinine, used in the albumin/creatinine and protein/creatinine ratios, is reported in different units and is not interchangeable here.
• Never convert creatinine to creatinine clearance by a fixed factor: clearance also depends on age, sex, and weight.

Related Tools

• Creatinine clearance calculator
• GFR unit converter
• Creatinine normal range