Quick answer: to convert cholesterol from mg/dL to mmol/L, divide by 38.67; triglycerides, divide by 88.57; glucose, divide by 18.02. Vitamin D in ng/mL times 2.496 gives nmol/L, testosterone in ng/dL divided by 28.84 gives nmol/L, and creatinine in mg/dL times 88.4 gives umol/L. HbA1c uses a formula: mmol/mol = (% - 2.152) / 0.09148. This lab unit converter does all of these both ways.
Converter
Type in either box and the other updates. Once you have US units, the blood test results checker shows whether each number is low, in range, borderline or high.
Conversion factors
| Biomarker | US unit | SI unit | US to SI | Source |
|---|---|---|---|---|
| Cholesterol (total, LDL, HDL, non-HDL) | mg/dL | mmol/L | mmol/L = mg/dL / 38.67 (AMA factor 0.0259) | AMA Manual of Style |
| Triglycerides | mg/dL | mmol/L | mmol/L = mg/dL / 88.57 (AMA factor 0.0113) | AMA Manual of Style |
| Glucose | mg/dL | mmol/L | mmol/L = mg/dL / 18.02 (AMA factor 0.0555) | AMA Manual of Style |
| Vitamin D (25-hydroxy) | ng/mL | nmol/L | nmol/L = ng/mL x 2.496 | AMA Manual of Style |
| Testosterone (total) | ng/dL | nmol/L | nmol/L = ng/dL / 28.84 (AMA factor 0.0347) | AMA Manual of Style |
| HbA1c | % (NGSP) | mmol/mol (IFCC) | mmol/mol = (% - 2.152) / 0.09148, the NGSP-IFCC master equation | NGSP |
| Creatinine | mg/dL | umol/L | umol/L = mg/dL x 88.4 | AMA Manual of Style |
The AMA Manual of Style publishes its factors in the US-to-SI direction (for example 0.0259 for cholesterol). We use the reciprocal the way most labs quote it, so 1 mmol/L of cholesterol equals 38.67 mg/dL. The two give the same answer to two decimal places for any number you will see on a report. Ratios such as total cholesterol to HDL, or triglycerides to HDL in mmol/L, are unit-free in the first case but not the second: a triglyceride to HDL ratio of 3.0 in mg/dL is about 1.3 in mmol/L, as our triglyceride to HDL ratio guide explains.
Common values converted
These are the cut-offs you are most likely to be comparing against, converted with the factors above.
Cholesterol (total, LDL, HDL, non-HDL)
| mg/dL | 40 | 60 | 100 | 130 | 160 | 190 | 200 | 240 |
|---|---|---|---|---|---|---|---|---|
| mmol/L | 1.03 | 1.55 | 2.59 | 3.36 | 4.14 | 4.91 | 5.17 | 6.21 |
Triglycerides
| mg/dL | 100 | 150 | 175 | 200 | 500 |
|---|---|---|---|---|---|
| mmol/L | 1.13 | 1.69 | 1.98 | 2.26 | 5.65 |
Glucose
| mg/dL | 70 | 99 | 100 | 125 | 126 | 140 | 200 |
|---|---|---|---|---|---|---|---|
| mmol/L | 3.88 | 5.49 | 5.55 | 6.94 | 6.99 | 7.77 | 11.1 |
Vitamin D (25-hydroxy)
| ng/mL | 12 | 20 | 30 | 50 | 100 |
|---|---|---|---|---|---|
| nmol/L | 30.0 | 49.9 | 74.9 | 125 | 250 |
Testosterone (total)
| ng/dL | 264 | 300 | 500 | 916 | 1000 |
|---|---|---|---|---|---|
| nmol/L | 9.15 | 10.4 | 17.3 | 31.8 | 34.7 |
HbA1c
| % (NGSP) | 5 | 5.7 | 6 | 6.5 | 7 | 8 |
|---|---|---|---|---|---|---|
| mmol/mol (IFCC) | 31 | 39 | 42 | 48 | 53 | 64 |
Creatinine
| mg/dL | 0.5 | 0.7 | 0.95 | 1 | 1.3 | 2 |
|---|---|---|---|---|---|---|
| umol/L | 44.2 | 61.9 | 84.0 | 88.4 | 115 | 177 |
Some cut-offs round differently in each system. The ADA's prediabetes line for fasting glucose is 100 mg/dL, which converts to 5.55 mmol/L; MedlinePlus quotes it as 5.6 mmol/L. An LDL of 100 mg/dL is 2.59 mmol/L and is usually written 2.6. When a guideline gives its own number in both units, use the guideline's number rather than your own conversion.
Why US and SI units differ
US labs mostly report mass per volume: milligrams per deciliter (mg/dL) or nanograms per deciliter (ng/dL). Most of the world uses the International System (SI), which reports amount of substance per volume: millimoles per liter (mmol/L) or nanomoles per liter (nmol/L). A mole is a fixed number of molecules, so converting needs the molecule's weight, and that is why every marker has its own factor.
- Cholesterol and glucose are the two you meet most. Canada, the UK, Europe and Australia report both in mmol/L, so a 5.2 mmol/L total cholesterol from a UK report is the same as 201 mg/dL.
- Vitamin D is reported in ng/mL in the US and nmol/L elsewhere. The NIH's adequacy line of 20 ng/mL is 50 nmol/L.
- Testosterone appears in ng/dL in the US and nmol/L in Europe. The AUA's 300 ng/dL line is about 10.4 nmol/L.
- HbA1c is a special case. The US reports percent (NGSP units), while the UK and much of Europe report mmol/mol (IFCC units). The CDC's 5.7% prediabetes line is 39 mmol/mol and the 6.5% diabetes line is 48 mmol/mol.
- Some units are equivalent and need no maths: ng/mL and mcg/L for ferritin, IU/L and mIU/mL for FSH and LH, mIU/L and uIU/mL for TSH.
Two warnings. First, Lp(a) cannot be converted between mg/dL and nmol/L with a fixed factor, because particle size varies between people. Second, check the unit twice before you compare a result with a range: a vitamin D of 30 means sufficient in ng/mL and deficient-to-inadequate in nmol/L. For how a full report is laid out, see our guide to reading blood test results and the biomarker library.
Frequently asked questions
How do I convert cholesterol from mg/dL to mmol/L?
Divide by 38.67. An LDL of 130 mg/dL is 3.36 mmol/L, and a total cholesterol of 200 mg/dL is 5.17 mmol/L. To go back, multiply mmol/L by 38.67. The same factor works for total, LDL, HDL and non-HDL cholesterol.
Why is the triglyceride factor different from cholesterol?
Because the conversion depends on the molecule's weight. A triglyceride molecule is heavier than a cholesterol molecule, so the same mg/dL number is fewer mmol/L: divide triglycerides by 88.57, not 38.67.
How do I convert HbA1c from percent to mmol/mol?
Use the NGSP-IFCC master equation: mmol/mol = (% - 2.152) / 0.09148. So 5.7% is 39 mmol/mol, 6.5% is 48 mmol/mol and 7% is 53 mmol/mol. It is not a single multiplication factor.
Can I convert Lp(a) from mg/dL to nmol/L?
Not accurately. Lp(a) particles vary in size from person to person, so no fixed factor works. Guidelines give separate cut-offs in each unit (30 and 50 mg/dL, or 75 and 125 nmol/L). Read our Lp(a) guide for details.