LDL Cholesterol Calculator — Friedewald Equation
Enter your Total Cholesterol, HDL and Triglyceride values from a standard lipid panel and get your estimated LDL using the Friedewald equation — supports both mg/dL and mmol/L.
單位
mg/dL
mg/dL
mg/dL
Near Optimal (100–129)
- 1
VLDL estimate
150 ÷ 5 = 30VLDL ≈ Triglycerides ÷ 5 (Friedewald assumption for mg/dL) - 2
Subtract HDL and VLDL from Total Cholesterol
200 − 55 − 30 = 115
此計算機如何運作？
LDL = Total Cholesterol − HDL − (Triglycerides / 5) in mg/dL, or − (TG / 2.2) in mmol/L. This Friedewald equation is valid only when Triglycerides ≤ 400 mg/dL. AHA 2019 targets: < 70 mg/dL for very high-risk patients, < 100 for high-risk, < 130 near-optimal. Not a substitute for clinical advice.
公式
How this is calculated
The Friedewald equation (1972) is the most widely used indirect method for estimating LDL-C from a standard lipid panel that reports Total Cholesterol, HDL and Triglycerides. It rests on the observation that VLDL cholesterol is approximately TG / 5 (in mg/dL) under normal conditions. Since Total Cholesterol = LDL + HDL + VLDL, solving for LDL gives: LDL = TC − HDL − TG/5.
The equation is not valid when Triglycerides exceed 400 mg/dL (4.52 mmol/L) because the VLDL/TG ratio breaks down at high TG levels — for example in type III hyperlipidaemia or severe hypertriglyceridaemia. In those cases direct LDL measurement (ultracentrifugation or the beta-quantification method) should be used instead. More recent alternatives such as the Martin/Hopkins equation (2013) or the NIH equation may be more accurate in low-LDL or high-TG populations, but the Friedewald formula remains standard in most clinical settings.
The AHA/ACC 2019 guidelines classify LDL as: <70 mg/dL (very low/therapeutic target for very high risk patients), 70–99 optimal, 100–129 near optimal, 130–159 borderline high, 160–189 high, ≥190 very high. These thresholds inform but do not replace individualised clinical decisions.
常見問題
For most adults with Triglycerides under 400 mg/dL, the Friedewald equation agrees closely with direct LDL measurement. It tends to underestimate LDL at very low levels (< 70 mg/dL) or high TG. If accuracy is important (e.g. deciding on statin therapy), ask your doctor about a direct LDL or Martin/Hopkins calculation.
Not with the Friedewald equation — TG is required to estimate VLDL. Some labs directly measure LDL (non-calculated), which does not need TG. If your panel shows a direct LDL value, use that instead of this calculator.
Non-HDL = Total Cholesterol − HDL. It captures all atherogenic particles (LDL, VLDL, IDL, Lp(a)), making it a more comprehensive cardiovascular risk marker than LDL alone — and it requires no fasting. Optimal Non-HDL is < 130 mg/dL for most adults.
也稱為
TG we-Calculate Editorial Team. (2026). LDL Cholesterol Calculator — Friedewald Equation [Online calculator]. TG we-Calculate. https://we-calculate.com/zh-tw/calculator/ldl-calculator
TG we-Calculate Editorial Team. "LDL Cholesterol Calculator — Friedewald Equation." TG we-Calculate. 2026. https://we-calculate.com/zh-tw/calculator/ldl-calculator.
TG we-Calculate Editorial Team, "LDL Cholesterol Calculator — Friedewald Equation," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/zh-tw/calculator/ldl-calculator
@misc{wecalculate_ldl_calculator, title = {LDL Cholesterol Calculator — Friedewald Equation}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/zh-tw/calculator/ldl-calculator}}, year = {2026}, note = {TG we-Calculate} }
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