The Martin equation (also called the Hopkins method) estimates LDL cholesterol (LDL-C) from a standard lipid panel. It improves on the Friedewald equation by replacing the fixed triglyceride ÷ 5 factor with a novel factor that varies with triglycerides and non-HDL cholesterol.
This approach was compared with Friedewald in Martin et al., JAMA 2013;310(19):2061-8.
Equations
Non-HDL cholesterol = Total cholesterol - HDL cholesterol
LDL cholesterol = Non-HDL cholesterol - (Triglycerides / Novel factor)
The novel factor represents the triglyceride to VLDL-cholesterol ratio. It is looked up from a table indexed by triglyceride level (mg/dL) and non-HDL cholesterol (mg/dL).
Novel factor table
Columns are non-HDL cholesterol strata (mg/dL). Rows are triglyceride strata (mg/dL).
| Triglycerides (mg/dL) |
<100 |
100-129 |
130-159 |
160-189 |
190-219 |
≥220 |
| 7-49 | 3.5 | 3.4 | 3.3 | 3.3 | 3.2 | 3.1 |
| 50-56 | 4.0 | 3.9 | 3.7 | 3.6 | 3.6 | 3.4 |
| 57-61 | 4.3 | 4.1 | 4.0 | 3.9 | 3.8 | 3.6 |
| 62-66 | 4.5 | 4.3 | 4.1 | 4.0 | 3.9 | 3.9 |
| 67-71 | 4.7 | 4.4 | 4.3 | 4.2 | 4.1 | 3.9 |
| 72-75 | 4.8 | 4.6 | 4.4 | 4.2 | 4.2 | 4.1 |
| 76-79 | 4.9 | 4.6 | 4.5 | 4.3 | 4.3 | 4.2 |
| 80-83 | 5.0 | 4.8 | 4.6 | 4.4 | 4.3 | 4.2 |
| 84-87 | 5.1 | 4.8 | 4.6 | 4.5 | 4.4 | 4.3 |
| 88-92 | 5.2 | 4.9 | 4.7 | 4.6 | 4.4 | 4.3 |
| 93-96 | 5.3 | 5.0 | 4.8 | 4.7 | 4.5 | 4.4 |
| 97-100 | 5.4 | 5.1 | 4.8 | 4.7 | 4.5 | 4.3 |
| 101-105 | 5.5 | 5.2 | 5.0 | 4.7 | 4.6 | 4.5 |
| 106-110 | 5.6 | 5.3 | 5.0 | 4.8 | 4.6 | 4.5 |
| 111-115 | 5.7 | 5.4 | 5.1 | 4.9 | 4.7 | 4.5 |
| 116-120 | 5.8 | 5.5 | 5.2 | 5.0 | 4.8 | 4.6 |
| 121-126 | 6.0 | 5.5 | 5.3 | 5.0 | 4.8 | 4.6 |
| 127-132 | 6.1 | 5.7 | 5.3 | 5.1 | 4.9 | 4.7 |
| 133-138 | 6.2 | 5.8 | 5.4 | 5.2 | 5.0 | 4.7 |
| 139-146 | 6.3 | 5.9 | 5.6 | 5.3 | 5.0 | 4.8 |
| 147-154 | 6.5 | 6.0 | 5.7 | 5.4 | 5.1 | 4.8 |
| 155-163 | 6.7 | 6.2 | 5.8 | 5.4 | 5.2 | 4.9 |
| 164-173 | 6.8 | 6.3 | 5.9 | 5.5 | 5.3 | 5.0 |
| 174-185 | 7.0 | 6.5 | 6.0 | 5.7 | 5.4 | 5.1 |
| 186-201 | 7.3 | 6.7 | 6.2 | 5.8 | 5.5 | 5.2 |
| 202-220 | 7.6 | 6.9 | 6.4 | 6.0 | 5.6 | 5.3 |
| 221-247 | 8.0 | 7.2 | 6.6 | 6.2 | 5.9 | 5.4 |
| 248-292 | 8.5 | 7.6 | 7.0 | 6.5 | 6.1 | 5.6 |
| 293-399 | 9.5 | 8.3 | 7.5 | 7.0 | 6.5 | 5.9 |
| 400-13975 | 11.9 | 10.0 | 8.8 | 8.1 | 7.5 | 6.7 |
Units
- Total cholesterol and HDL: mg/dL or mmol/L (conversion factor 38.66976 for mmol/L to mg/dL).
- Triglycerides: mg/dL (required for the novel factor table).
Notes
- The novel factor improves LDL estimation across a wide range of triglyceride levels, including ranges where Friedewald is less reliable.
- This calculator does not replace clinical judgment or laboratory measurement when a direct LDL assay is indicated.
- Discuss your lipid results with your healthcare provider.
