Medical Lab Unit Converter (mg/dL ↔ mmol/L)
Convert 10 common serum and plasma laboratory values between conventional and SI reporting units using analyte-specific factors.
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Convert common serum and plasma laboratory results between conventional and SI reporting units. Select the analyte first—there is no single mg/dL ↔ mmol/L factor that works for every substance.
Input
Converted value
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Unit conversion only; no normal or abnormal classification.
Enter a laboratory value to see the conversion equation and published factor.
This tool converts reporting units only. It does not interpret the result, determine a medication dose, or replace the reference interval provided by the reporting laboratory.
About
This calculator converts selected serum and plasma laboratory results between conventional mass-concentration units and SI amount-of-substance concentration units. Each analyte and reporting quantity has its own factor. The calculation changes report units only; it does not create a new measurement, interpret the result, or add precision. [1, 2]
Interpretation
Factors are analyte-specific. Displayed results are rounded to three significant digits; conversion does not add measurement precision.
| Analyte | Conventional unit | SI unit | Conventional → SI factor | Source |
|---|---|---|---|---|
| Glucose | mg/dL | mmol/L | ×0.05551 | [2, 3] |
| Cholesterol (total, HDL-C, LDL-C, non-HDL-C) | mg/dL | mmol/L | ×0.02586 | [2, 4] |
| Triglycerides | mg/dL | mmol/L | ×0.01129 | [2, 5] |
| Creatinine | mg/dL | µmol/L | ×88.4 | [2, 6] |
| BUN (urea nitrogen) | mg/dL BUN | mmol/L urea | ×0.357 | [2, 3] |
| Total bilirubin | mg/dL | µmol/L | ×17.1 | [2, 3] |
| Total calcium | mg/dL | mmol/L | ×0.25 | [2, 3] |
| Magnesium | mg/dL | mmol/L | ×0.4114 (derived) | [7] |
| Phosphorus (inorganic phosphate) | mg/dL | mmol/L | ×0.3229 | [2, 3, 7] |
| Uric acid | mg/dL | µmol/L | ×59.48 | [2, 3] |
Why the factor depends on the analyte
mg/dL reports mass per volume, while mmol/L or µmol/L reports an amount of a specified substance per volume. The relationship therefore depends on the analyte and the reporting quantity; there is no universal mg/dL ↔ mmol/L factor. [1, 2]
BUN and urea clarification
A conventional BUN result in mg/dL reports urea nitrogen mass concentration, while the SI result in mmol/L reports urea. The named reporting quantities differ, so this is not a label replacement. [2, 3]
Lipids and creatinine
Cholesterol concentrations use 0.02586, while triglycerides use 0.01129; the factors are not interchangeable. This page does not calculate lipid fractions or change one fraction into another. Creatinine is commonly reported in µmol/L, rather than mmol/L, because that scale is easier to read at typical serum values. [4, 5, 6]
Phosphorus and phosphate naming
Conventional reports commonly label the result as phosphorus in mg/dL, while SI reports may use phosphorus or inorganic phosphate in mmol/L. The factor 0.3229 follows the phosphorus amount convention; it is not a conversion from elemental phosphorus mass to the mass of the full phosphate ion. [2, 3, 7]
Magnesium factor basis
The displayed magnesium factor 0.4114 is a derived factor based on the mg/dL-to-mmol/L scale and the CIAAW standard atomic weight for magnesium, 24.305. It is not presented as a CDC-published factor. [7]
Published factor precision
This runtime uses the factors displayed in the table. Official files may publish different decimal precision: the newer NHANES biochemistry file uses 0.0555, 0.0259, 0.0113, and 0.323, while the NHANES III table and specialized lipid files show 0.05551, 0.02586, 0.01129, and 0.3229. The final digit reflects publication precision and rounding. Do not mix factors within one conversion, and do not treat a converted result as more precise than the original measurement. [2, 3, 4, 5]
Rounding and interpretation
Calculations use the full stored factor and are rounded only for display. Compare a result only with a reference interval for the same analyte, reporting quantity, specimen context, and unit. Conversion cannot add measurement precision, classify a result, or determine treatment. Converting mg to mL requires a product concentration and is not supported here.
Worked examples
- 100 mg/dL glucose ≈ 5.55 mmol/L
- 200 mg/dL cholesterol ≈ 5.17 mmol/L
- 150 mg/dL triglycerides ≈ 1.69 mmol/L
- 1.00 mg/dL creatinine ≈ 88.4 µmol/L
- 20 mg/dL BUN ≈ 7.14 mmol/L urea
References
- BIPM. The International System of Units (SI), 9th edition, version 4.01. Revised June 2026.
- CDC/NCHS. NHANES III Second Laboratory Data File Documentation. Appendix 3: NHANES III SI Table. 1998.
- CDC/NCHS. NHANES August 2021–August 2023 Standard Biochemistry Profile. Published 2025.
- CDC/NCHS. NHANES August 2021–August 2023 HDL documentation.
- CDC/NCHS. NHANES 2017–March 2020 LDL and Triglycerides documentation.
- NIDDK. eGFR Equations for Adults: serum creatinine unit conversion.
- CIAAW. Abridged Standard Atomic Weights 2024.
FAQ
No. mg/dL is a mass concentration, while mmol/L is an amount-of-substance concentration. The relationship depends on the specified analyte and reporting quantity, so glucose, cholesterol, creatinine, and other laboratory results require different factors.
For glucose, multiply mg/dL by 0.05551 to obtain mmol/L. To convert mmol/L back to mg/dL, divide by 0.05551. For example, 100 mg/dL is approximately 5.55 mmol/L after display rounding.
No. Cholesterol concentrations use 0.02586, while triglycerides use 0.01129; the factors cannot be exchanged. This page converts the reported cholesterol concentration for total, HDL-C, LDL-C, or non-HDL-C, but it does not calculate LDL-C, HDL-C, non-HDL-C, or convert one lipid fraction into another.
Typical serum creatinine concentrations are small when expressed in moles per liter, so µmol/L provides a more readable scale. The published relationship used here is 1 mg/dL = 88.4 µmol/L.
BUN in mg/dL reports the mass concentration of the nitrogen contained in urea. The corresponding SI result is commonly reported as mmol/L urea. The factor therefore connects two related reporting quantities rather than merely changing the unit label on the same name.
The calculator uses published analyte-specific factors, but the factors and displayed results are rounded. A unit conversion also cannot add precision to the original laboratory measurement, so small differences between properly sourced tables may reflect rounding conventions.
No. The conversion preserves the reported quantity in another unit system; it does not classify the result. Interpret the original or converted value using the reference interval supplied by the reporting laboratory and the relevant clinical context.
No. Converting a mass such as mg to a volume such as mL requires a specified product concentration, and medication dosing requires additional drug- and patient-specific information. This page only converts the listed laboratory reporting units.
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Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.