Cholesterol Calculator — LDL, Ratios & Conversions
Professional cholesterol calculator: compute LDL-C (Friedewald or NIH Sampson), non-HDL, TC/HDL ratio, and unit conversions (mg/dL ⇆ mmol/L). Includes formulas, methodology, examples, and FAQs.
Sampson improves accuracy at low LDL and high TG; Friedewald remains valid when TG < 400 mg/dL.
How to Use This Calculator
Enter the latest lipid panel values from your lab report. Pick the NIH Sampson formula to guard against low LDL or high TG, or choose Friedewald when TG are under 400 mg/dL and the sample is fasting.
Toggle the display units to match your lab (mg/dL or mmol/L). The engine always stores mg/dL internally and recalculates immediately when you switch, so you never lose precision.
Methodology
We compute LDL-C via your chosen equation, subtract HDL-C to derive non-HDL-C, and show key lipid ratios. All results round according to standard clinical reporting (one decimal for mg/dL, two for SI units and ratios).
- LDL labels pair with badges that reflect guideline thresholds for optimal, near-optimal, borderline high, and higher-risk categories.
- Non-HDL-C is included so you can see the atherogenic burden beyond LDL alone.
- TC/HDL and TG/HDL ratios highlight cardiometabolic risk from the full panel.
Full original guide (expanded)
Audit: Complete
This calculator was audited to capture the LDL formulas, derived ratios, and SI conversions used in the engine.
Verified by Ugo Candido on 2026-01-19. Profile · LinkedIn.