Convert between mmol/L or µmol/L and mg/dL for a selected analyte. The factor is substance-specific—18.018 applies to glucose, not every lab value.
Related Calculators
Is there one mmol/L to mg/dL conversion factor?
No—there is no universal factor. mmol/L counts an amount of a named substance, while mg/dL measures its mass. You must know the analyte before converting. Multiplying by 18.018 is appropriate for glucose; cholesterol, triglycerides, creatinine, electrolytes, and other substances use different factors or reporting conventions.
Select the analyte printed on the laboratory report, keep the original unit attached to the number, and use the same stored factor in both directions. This page converts units only; it does not classify the result.
How the mmol/L to mg/dL formula works
For a chemically defined substance with molar mass M in grams per mole, the forward factor is M divided by 10. The reverse calculation divides by that same factor:
÷ 1,000 mmol
÷ 1 mol
÷ 1 g
÷ 10 dL
The mole and gram units cancel, leaving (M/10) mg/dL. NIST defines molar mass as mass divided by amount of substance and documents the SI volume relationships used here: NIST Guide to SI, Chapter 8 and NIST volume units.
Each bar represents the mg/dL result for the same concentration, 1 mmol/L. Bar length is scaled to the largest result. Triglycerides use an accepted clinical reporting factor rather than one exact molecular mass.
| Analyte | Input | Factor | Converted mass concentration |
|---|---|---|---|
| Glucose | 1 mmol/L | × 18.018 | 18.018 mg/dL |
| Cholesterol | 1 mmol/L | × 38.67 | 38.67 mg/dL |
| Triglycerides | 1 mmol/L | × 88.57 | 88.57 mg/dL |
Analyte factors and reporting conventions
The calculator stores one forward factor F in mg/dL per mmol/L and reverses the conversion by dividing by the same F. This avoids drift from mixing independently rounded forward and reverse constants. The entity named in the result matters: BUN is nitrogen mass, and phosphate is reported here as phosphorus mass.
| Analyte | Forward factor F | Reverse action | Convention and unit note | Official or primary basis |
|---|---|---|---|---|
| Glucose | × 18.018 | ÷ 18.018 | Glucose only; CDC publishes 18.02 forward and 0.0555 reverse. | CDC/NHANES glucose method |
| Total cholesterol | × 38.67 | ÷ 38.67 | Converts cholesterol mass concentration. | AHRQ/NCBI lipid appendix |
| HDL cholesterol | × 38.67 | ÷ 38.67 | HDL-C is cholesterol mass, not the mass of an entire lipoprotein particle. | CDC/NHANES SI table |
| LDL cholesterol | × 38.67 | ÷ 38.67 | LDL-C is cholesterol mass, not the mass of an entire lipoprotein particle. | CDC/NHANES lipid documentation |
| Triglycerides | × 88.57 | ÷ 88.57 | Accepted clinical reporting factor for a mixture; not one exact molecular mass. | AHRQ/NCBI lipid appendix |
| Blood urea nitrogen (BUN) | × 2.801 | ÷ 2.801 | mmol/L urea ↔ mg/dL nitrogen. This is not mg/dL of the complete urea molecule. | CDC/NHANES SI table |
| Creatinine | × 11.312 | ÷ 11.312 | µmol/L is more common clinically; 1 mmol/L = 1,000 µmol/L. | Mayo Clinic Laboratories SI table |
| Uric acid (urate) | × 16.811 | ÷ 16.811 | µmol/L is also common; the displayed factor follows the documented molecular mass. | NIST Chemistry WebBook |
| Lactate | × 9.008 | ÷ 9.008 | Conventional lactic-acid-equivalent mass conversion. | NIST Chemistry WebBook |
| β-Hydroxybutyrate (BHB) | × 10.4106 | ÷ 10.4106 | β-hydroxybutyric-acid equivalent; conversion only. | NIST Chemistry WebBook |
| Ethanol | × 4.6068 | ÷ 4.6068 | Mass conversion only; no impairment or legal interpretation. | NIST Chemistry WebBook |
| Sodium (Na+) | × 2.29898 | ÷ 2.29898 | mg/dL is uncommon on clinical reports; do not substitute mEq/L. | CIAAW standard atomic weights |
| Potassium (K+) | × 3.90983 | ÷ 3.90983 | mg/dL is uncommon on clinical reports; do not substitute mEq/L. | CIAAW standard atomic weights |
| Calcium (Ca2+) | × 4.0078 | ÷ 4.0078 | Total and ionized calcium are not interchangeable; mEq/L is a separate unit. | KDIGO-derived CADTH/NCBI table |
| Magnesium (Mg2+) | × 2.4305 | ÷ 2.4305 | Do not treat mg/dL, mmol/L, and mEq/L as interchangeable. | CIAAW standard atomic weights |
| Inorganic phosphate (as phosphorus) | × 3.09738 | ÷ 3.09738 | The mg/dL side is phosphorus mass, not mass of the full PO4 ion. | KDIGO-derived CADTH/NCBI table |
Using a custom molar mass
Use the custom option only when the chemical species is explicitly defined and you know its molar mass M in g/mol. The calculator derives F = M/10, then multiplies by F going to mg/dL or divides by F going to mmol/L. A custom molecular mass is not a reliable substitute for an established reporting convention such as triglycerides, BUN, or phosphate as phosphorus, and it cannot convert mEq/L by relabeling that unit.
Glucose conversion chart
These are arithmetic lookups using the stored glucose factor 18.018. They answer common value searches without attaching a diagnosis, target, or laboratory interpretation. Rounded values are marked with approximately equal signs.
| Glucose in mmol/L | Calculation | Glucose in mg/dL |
|---|---|---|
| 3.9 mmol/L | 3.9 × 18.018 | ≈ 70.3 mg/dL |
| 5.0 mmol/L | 5.0 × 18.018 | ≈ 90.1 mg/dL |
| 5.5 mmol/L | 5.5 × 18.018 | ≈ 99.1 mg/dL |
| 5.6 mmol/L | 5.6 × 18.018 | ≈ 100.9 mg/dL |
| 6.0 mmol/L | 6.0 × 18.018 | ≈ 108.1 mg/dL |
| 7.0 mmol/L | 7.0 × 18.018 | ≈ 126.1 mg/dL |
| 7.8 mmol/L | 7.8 × 18.018 | ≈ 140.5 mg/dL |
| 10.0 mmol/L | 10.0 × 18.018 | ≈ 180.2 mg/dL |
| 11.1 mmol/L | 11.1 × 18.018 | ≈ 200 mg/dL |
| Glucose in mg/dL | Calculation | Glucose in mmol/L |
|---|---|---|
| 70 mg/dL | 70 ÷ 18.018 | ≈ 3.89 mmol/L |
| 99 mg/dL | 99 ÷ 18.018 | ≈ 5.49 mmol/L |
| 100 mg/dL | 100 ÷ 18.018 | ≈ 5.55 mmol/L |
| 126 mg/dL | 126 ÷ 18.018 | ≈ 6.99 mmol/L |
| 140 mg/dL | 140 ÷ 18.018 | ≈ 7.77 mmol/L |
| 180 mg/dL | 180 ÷ 18.018 | ≈ 9.99 mmol/L |
| 200 mg/dL | 200 ÷ 18.018 | ≈ 11.1 mmol/L |
Common laboratory-unit traps
Lipids: cholesterol is not triglycerides
Total, HDL, and LDL cholesterol use 38.67. Triglycerides use the accepted clinical factor 88.57. Applying the cholesterol factor to triglycerides—or the glucose shortcut to either—gives the wrong conversion. The factors are documented by the AHRQ/NCBI lipid appendix.
Creatinine: µmol/L is common
A report showing 88.4 µmol/L does not show 88.4 mmol/L. First divide by 1,000: 88.4 µmol/L = 0.0884 mmol/L. Then 0.0884 × 11.312 ≈ 1.00 mg/dL. Mayo publishes the corresponding reverse factor of 0.0884 mmol/L per mg/dL in its SI conversion table.
BUN is not the mass of complete urea
For BUN, the SI side is mmol/L of urea and the mg/dL side is the mass of nitrogen. Thus 7 mmol/L urea × 2.801 ≈ 19.61 mg/dL BUN. Do not relabel that result as mg/dL urea. The convention is listed in the CDC/NHANES SI table.
Phosphate reported as phosphorus
This option converts mmol/L inorganic phosphate to mg/dL of phosphorus. At 1.2 mmol/L, 1.2 × 3.09738 ≈ 3.72 mg/dL phosphorus. It is not the mass of the complete PO4 ion. See the KDIGO-derived CADTH/NCBI table.
Electrolytes: mEq/L is not mg/dL
Sodium and potassium are commonly shown as mmol/L or mEq/L; mg/dL is unusual. mEq/L expresses charge-equivalent concentration, while mg/dL expresses mass. The numerical relationship also depends on ionic charge, so calcium and magnesium cannot be handled by simply copying an mEq/L value into an mg/dL field. See the Merck Manual unit relationships and CIAAW atomic weights.
Uric acid may also use µmol/L
As with creatinine, check whether a uric-acid result is in µmol/L before entering it. CDC documents 59.48 µmol/L per mg/dL; this page’s mmol/L factor is based on the NIST molecular mass. Small differences can appear when a rounded clinical reciprocal is inverted.
Worked conversion examples
Glucose
5.5 mmol/L × 18.018 = 99.099 mg/dL, displayed as ≈ 99.1 mg/dL.
Total cholesterol
5.2 mmol/L × 38.67 = 201.084 mg/dL, displayed as ≈ 201.1 mg/dL.
Triglycerides
1.7 mmol/L × 88.57 = 150.569 mg/dL, displayed as ≈ 150.6 mg/dL.
Calcium
2.5 mmol/L × 4.0078 = 10.0195 mg/dL, displayed as ≈ 10.02 mg/dL. The conversion does not make total and ionized calcium interchangeable.
Rounding and calculator methodology
The calculator keeps the documented forward factor at full stored precision, performs the arithmetic before rounding, and divides by that same factor in reverse. Rounded answers use ≈. Glucose and lipids are generally shown to one decimal in mg/dL and two decimals in mmol/L; other analytes may use two decimals in mg/dL and three in mmol/L. Trailing zeros may be removed in compact results, and the expanded calculation preserves the factor so the method remains auditable.
A small difference between this page and another reputable table can come from the table’s rounded reciprocal. For example, a source may publish a conventional-unit-to-SI multiplier with fewer digits than the molar-mass-derived forward factor. This page does not mix two independently rounded constants.
What this conversion does not tell you
Conversion only
A converted value is the same measurement expressed in another unit. This calculator does not diagnose a condition, recommend treatment, or determine what the result means for a person.
Use the laboratory’s reference range
Reference intervals and decision limits can depend on the laboratory method, specimen, timing, population, and clinical context. Compare with the range printed by the performing laboratory and discuss unexpected or concerning results with a qualified clinician. MedlinePlus explains why laboratory reference ranges can differ.
Match both analyte and unit
mmol/L, µmol/L, mg/dL, and mEq/L are not interchangeable labels. Confirm the analyte, specimen convention, and original unit before calculating—especially for creatinine, uric acid, BUN, electrolytes, and phosphate as phosphorus.
Urgent symptoms need urgent care
If you feel seriously unwell or have symptoms of a medical emergency, seek urgent local medical care rather than relying on this calculator or waiting for an online conversion.
Frequently asked questions
Why can’t I multiply every mmol/L value by 18?
Because 18.018 is the glucose factor. mmol counts entities and mg measures their mass, so a different analyte generally has a different mass per mole. Cholesterol uses 38.67 and triglycerides use the conventional factor 88.57.
How do I convert mg/dL back to mmol/L?
Choose the analyte and divide the mg/dL value by that analyte’s stored forward factor. For glucose, 100 mg/dL ÷ 18.018 ≈ 5.55 mmol/L. The calculator uses the same factor in both directions rather than a separately rounded reciprocal.
Why does creatinine often use µmol/L instead of mmol/L?
The concentrations are often small enough that µmol/L is the practical clinical unit. There are 1,000 µmol in 1 mmol, so 88.4 µmol/L is 0.0884 mmol/L—not 88.4 mmol/L. Use the calculator’s µmol/L option when that is the unit on the report.
Are urea and BUN the same unit conversion?
No. BUN in mg/dL reports the mass of nitrogen contained in urea, while a urea result may report the mass of the complete urea molecule. This calculator’s BUN factor 2.801 is specifically mmol/L urea to mg/dL nitrogen.
Why is triglyceride conversion not based on one exact molar mass?
Circulating triglycerides are a mixture rather than one uniform compound. The factor 88.57 is an accepted clinical reporting convention supported by laboratory conversion tables.
Can I enter an mEq/L electrolyte result in the mg/dL box?
No. mEq/L describes ionic charge equivalents and mg/dL describes mass. Use a conversion designed for the exact ion and source unit; do not relabel the same number.
Does converting a result change its laboratory interpretation?
No. Unit conversion does not change the underlying measurement. Keep the converted result paired with the correct analyte and compare it with guidance or a reference interval expressed in the same unit and applicable context.
Method sources
- National Institute of Standards and Technology. NIST Guide to SI, Chapter 8 and SI units of volume.
- CDC/NHANES. Glucose laboratory method and SI conversion table.
- National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes in America conversion appendix.
- Agency for Healthcare Research and Quality, via NCBI Bookshelf. Cholesterol and triglyceride conversion factors.
- Mayo Clinic Laboratories. SI unit conversion table.
- NIST Chemistry WebBook molecular-mass records: glucose, cholesterol, creatinine, uric acid, lactic acid, 3-hydroxybutyric acid, and ethanol.
- Commission on Isotopic Abundances and Atomic Weights. Standard atomic weights.
- KDIGO-derived CADTH table, via NCBI Bookshelf. Calcium and inorganic phosphate conversions.
- U.S. National Library of Medicine. How to understand laboratory results.
Source selection favors official measurement bodies, government laboratory documentation, primary chemical records, and clinical laboratory conversion tables. Source links are placed both beside the claims they support and in this consolidated method list.
