Calculate LDL cholesterol using Friedewald and Martin-Hopkins formulas, evaluate non-HDL-C, TC:HDL ratio, TG:HDL ratio, remnant cholesterol, and assess cardiovascular risk by ATP III guidelines.
Low-density lipoprotein cholesterol (LDL-C) is the primary atherogenic lipoprotein and the cornerstone of cardiovascular risk assessment and statin therapy goals. Most standard lipid panels do not measure LDL directly — instead, it is calculated from total cholesterol, HDL cholesterol, and triglycerides using validated equations.
This calculator implements both the classic Friedewald equation (LDL = TC – HDL – TG/5, valid when triglycerides are ≤400 mg/dL) and the newer Martin-Hopkins formula, which uses an adjustable triglyceride factor based on the patient's own triglyceride and non-HDL cholesterol levels. The Martin-Hopkins equation has been validated in over 1.3 million lipid profiles and is significantly more accurate than Friedewald, particularly when triglycerides are elevated or LDL is very low.
Beyond calculated LDL, this tool computes non-HDL cholesterol (which captures all atherogenic particles including VLDL and IDL), the TC:HDL and TG:HDL ratios, and remnant cholesterol. The TG:HDL ratio is a validated surrogate marker for insulin resistance and small dense LDL particles. Together, these metrics provide a far more complete picture of atherogenic risk than LDL alone, helping guide statin intensity decisions per the 2018 AHA/ACC multi-society cholesterol guidelines.
This calculator provides dual-formula LDL calculation (Friedewald + Martin-Hopkins), automatically flags Friedewald limitations at high triglyceride levels, computes comprehensive lipid ratios including the insulin-resistance marker TG:HDL, and categorizes LDL risk per current guidelines. It also incorporates advanced markers (ApoB, Lp(a), remnant cholesterol) for a complete atherogenic risk profile. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain.
Friedewald: LDL = TC – HDL – TG/5 (TG ≤400). Martin-Hopkins: LDL = TC – HDL – TG/adjusted factor (factor varies from 4.9 to 6.5 based on TG level). Non-HDL = TC – HDL. Remnant cholesterol = Non-HDL – LDL.
Result: LDL (Friedewald) = 156 mg/dL, LDL (Martin-Hopkins) = 161 mg/dL, Non-HDL = 190, TC:HDL = 5.2, Borderline High risk
With TC 235, HDL 45, TG 170: Friedewald gives LDL = 235 - 45 - 34 = 156. Martin-Hopkins uses a TG factor of 5.9 instead of 5, giving LDL = 161. Non-HDL of 190 exceeds the 130 target. The TC:HDL ratio of 5.2 also indicates elevated atherogenic risk.
Use consistent units, verify assumptions, and document conversion standards for repeatable outcomes.
Most mistakes come from mixed standards, rounding too early, or misread labels. Recheck final values before use. ## Practical Notes
Use this for repeatability, keep assumptions explicit. ## Practical Notes
Track units and conversion paths before applying the result. ## Practical Notes
Use this note as a quick practical validation checkpoint. ## Practical Notes
Keep this guidance aligned to expected inputs. ## Practical Notes
Use as a sanity check against edge-case outputs. ## Practical Notes
Capture likely mistakes before publishing this value. ## Practical Notes
Document expected ranges when sharing results.
Friedewald is unreliable when triglycerides exceed 400 mg/dL. It also underestimates LDL when TG are 200–399 and overestimates when LDL is very low (<70). The Martin-Hopkins equation is preferred in these cases.
Guidelines now accept non-fasting lipid panels for screening. However, triglycerides are significantly affected by recent meals, and calculated LDL accuracy depends on TG. For treatment decisions, fasting (9–12 hours) is still preferred.
Non-HDL = TC – HDL. It captures all atherogenic lipoproteins (LDL + VLDL + IDL + Lp(a)). It is a better predictor than LDL-C alone, especially for patients with elevated triglycerides, and does not require fasting.
AHA/ACC 2018 guidelines: <70 mg/dL for very high-risk (ASCVD, post-MI), <100 for high risk (diabetes, familial hypercholesterolemia), <130 for intermediate risk. Some European guidelines target even lower (<55 mg/dL) for the highest-risk patients.
A TG:HDL ratio >3.5 is a validated marker for insulin resistance and the presence of small dense LDL particles (pattern B), both independent cardiovascular risk factors.
ApoB measures the total number of atherogenic particles and is especially useful when LDL-C and non-HDL-C are discordant. Lp(a) is genetically determined, not modified by statins, and should be checked at least once in every adult to assess residual cardiovascular risk.