Calculate LDL cholesterol with Friedewald and Martin-Hopkins equations, then compare it with non-HDL cholesterol and common lipid ratios in one worksheet.
Low-density lipoprotein cholesterol (LDL-C) is a core part of standard lipid-panel interpretation. Many routine lab reports still calculate LDL from total cholesterol, HDL cholesterol, and triglycerides rather than measuring it directly.
This calculator shows both the classic Friedewald equation (LDL = TC – HDL – TG/5, valid when triglycerides are ≤400 mg/dL) and a simplified Martin-Hopkins-style estimate that uses a triglyceride-dependent divisor. It also calculates non-HDL cholesterol, remnant cholesterol, and common lipid ratios so the panel can be reviewed in context instead of reducing the result to one number.
The page is meant as a structured lipid reference aid. It can help show when the formula choice matters, when triglycerides make calculated LDL less dependable, and when non-HDL or a direct LDL result deserves more attention.
LDL-C is often reported as a single number, but the formula behind it matters when triglycerides are elevated or LDL is already low. This page keeps the common LDL estimates, non-HDL cholesterol, and basic ratios together so the lipid panel can be reviewed as a pattern instead of a lone result.
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
With TC 235, HDL 45, and TG 170: Friedewald gives LDL = 235 − 45 − 34 = 156. Using the triglyceride-adjusted divisor raises the estimate to 161. Non-HDL of 190 shows the broader burden of atherogenic cholesterol beyond the LDL number alone.
Friedewald works well when triglycerides are modest and LDL is not extremely low. Once triglycerides climb or LDL gets near the treatment threshold, the calculated value can drift enough to change how a panel is interpreted. That is the main reason the calculator shows both Friedewald and Martin-Hopkins side by side.
Non-HDL, ApoB, and the triglyceride-to-HDL ratio can reveal atherogenic risk that LDL alone misses, especially in insulin resistance or mixed dyslipidemia. Those supporting values are useful because they show whether the problem is isolated LDL elevation or a broader high-particle lipid pattern.
The equations assume the units match the formula being applied. Comparing a direct LDL result, a calculated LDL result, and the non-HDL value works best when the triglycerides and cholesterol inputs are interpreted from the same lipid panel.
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This page calculates LDL cholesterol from the entered lipid panel with two common estimation approaches: the classic Friedewald formula and a simplified triglyceride-adjusted divisor meant to approximate Martin-Hopkins-style behavior when triglycerides rise. It also reports non-HDL cholesterol, remnant cholesterol, and simple cholesterol ratios so the panel can be reviewed as a pattern rather than as a single LDL number.
The output is a lipid-panel interpretation aid, not a treatment protocol. Calculated LDL becomes less dependable when triglycerides are high, and treatment decisions still depend on the full cardiovascular risk picture, the underlying lab report, and whether a direct LDL or apolipoprotein measurement is available.
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.
Targets depend on the patient’s overall cardiovascular risk and the guideline framework being used. This page is best used to review the lipid numbers themselves rather than to set a personal treatment target.
It is a rough pattern marker that can suggest insulin resistance or triglyceride-rich dyslipidemia, but it is not a diagnosis by itself.
If triglycerides are high or the calculated and direct values differ meaningfully, it is reasonable to focus more on the direct result and on the rest of the lipid panel rather than treating one formula as definitive.