Medical Lab Unit Converter – mg/dL, mmol/L & µmol/L
Convert 11 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
Select a laboratory analyte to begin
mg/dL does not have one universal mmol/L conversion factor. Choose the reported analyte first.
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
Supported analytes and conversion factors
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] |
| Urea (whole molecule) | mg/dL urea | mmol/L urea | ×0.1665 (derived) | [1, 8] |
| 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] |
- Analyte
- Cholesterol (total, HDL-C, LDL-C, non-HDL-C)
- Conventional unit
- mg/dL
- SI unit
- mmol/L
- Conventional → SI factor
- ×0.02586
- Source
- [2, 4]
- Analyte
- Urea (whole molecule)
- Conventional unit
- mg/dL urea
- SI unit
- mmol/L urea
- Conventional → SI factor
- ×0.1665 (derived)
- Source
- [1, 8]
- Analyte
- BUN (urea nitrogen)
- Conventional unit
- mg/dL BUN
- SI unit
- mmol/L urea
- Conventional → SI factor
- ×0.357
- Source
- [2, 3]
- Analyte
- Magnesium
- Conventional unit
- mg/dL
- SI unit
- mmol/L
- Conventional → SI factor
- ×0.4114 (derived)
- Source
- [7]
Urea vs BUN: different reporting quantities
Whole urea and BUN are not interchangeable labels. Whole urea in mg/dL uses ×0.1665 to report mmol/L urea; BUN in mg/dL reports only the nitrogen mass contained in urea and uses ×0.357. Therefore, 20 mg/dL whole urea converts to about 3.33 mmol/L urea, while 20 mg/dL BUN converts to about 7.14 mmol/L urea. [1, 3, 8]
Common glucose mg/dL ↔ mmol/L conversions
Glucose only. These are unit conversions, not glucose targets, reference intervals, or diagnostic categories. [2]
| Glucose (mg/dL) | Glucose (mmol/L) |
|---|---|
| 70 | 3.89 |
| 100 | 5.55 |
| 120 | 6.66 |
| 140 | 7.77 |
| 180 | 9.99 |
| 200 | 11.1 |
- Glucose (mg/dL)
- 70
- Glucose (mmol/L)
- 3.89
- Glucose (mg/dL)
- 100
- Glucose (mmol/L)
- 5.55
- Glucose (mg/dL)
- 120
- Glucose (mmol/L)
- 6.66
- Glucose (mg/dL)
- 140
- Glucose (mmol/L)
- 7.77
- Glucose (mg/dL)
- 180
- Glucose (mmol/L)
- 9.99
- Glucose (mg/dL)
- 200
- Glucose (mmol/L)
- 11.1
Why mg/dL ↔ mmol/L 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 reporting quantity; there is no universal factor. [1, 2]
Creatinine and other µmol/L results
Creatinine, bilirubin, and uric acid use µmol/L here rather than mmol/L. Creatinine uses the published relationship 1 mg/dL = 88.4 µmol/L. Cholesterol and triglycerides remain separate mmol/L quantities with non-interchangeable factors. [4, 5, 6]
Phosphorus/phosphate and magnesium notes
The phosphorus factor 0.3229 follows the reported phosphorus amount convention; it is not a conversion to the mass of the full phosphate ion. Magnesium 0.4114 is derived from the mg/dL-to-mmol/L relationship and CIAAW standard atomic weight 24.305, not presented as a CDC-published factor. [2, 3, 7]
Precision, rounding and interpretation limits
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]
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.
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.
- NIST Chemistry WebBook, SRD 69. Urea (CAS 57-13-6), molecular formula CH4N2O, molecular weight 60.0553.
FAQ
Whole urea in mg/dL reports the mass of the full urea molecule and uses ×0.1665 to obtain mmol/L urea. BUN in mg/dL reports only the nitrogen mass contained in urea and uses ×0.357. For the same numeric input of 20 mg/dL, whole urea is about 3.33 mmol/L while BUN is about 7.14 mmol/L urea.
No. Unit conversion does not classify a result, add measurement precision, diagnose a condition, or determine treatment. Interpret the value with a reference interval for the same analyte, reporting quantity, specimen context, and unit; this page does not convert medication mass to volume or calculate a dose.
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Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.