Heart & Cholesterol Calculators: QTc, LDL & Vital Signs

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• [QTc calculator](/qtc-calculator) corrects the QT interval for heart rate using Bazett, Fridericia, Framingham and Hodges, with the AHA/ACCF/HRS thresholds for a long QT.
• [Normal respiratory rate by age](/normal-respiratory-rate) gives breathing-rate ranges from newborns to older adults, how to count breaths correctly, and how respiratory rate is used in NEWS2 and qSOFA scores.

Which cholesterol tool do you need?

A standard lipid panel reports total cholesterol, HDL cholesterol, triglycerides and usually a calculated LDL. The tools in this section help you convert, calculate and interpret those numbers:

• [LDL cholesterol calculator](/ldl-calculator) – calculates LDL with the NIH (Sampson) equation, valid up to triglycerides of 800 mg/dL, with the older Friedewald result for comparison.
• [Non-HDL cholesterol calculator](/non-hdl-cholesterol-calculator) – total cholesterol minus HDL; captures every atherogenic particle and needs no fasting.
• [Cholesterol ratio calculator](/cholesterol-ratio-calculator) – the total-to-HDL ratio used in risk calculators such as QRISK3.
• [Cholesterol mg/dL ↔ mmol/L converter](/cholesterol-mg-dl-to-mmol-l) – for total, LDL, HDL and non-HDL cholesterol (factor 38.67).
• [Triglycerides mg/dL ↔ mmol/L converter](/triglycerides-mg-dl-to-mmol-l) – triglycerides use a different factor (88.57).

Key lipid values at a glance

These are general population reference points. People with heart disease, diabetes or other high-risk conditions are usually given lower targets – for example, LDL below 70 mg/dL (1.8 mmol/L) or 55 mg/dL (1.4 mmol/L) in European guidelines.

How the numbers fit together

Total cholesterol is the sum of cholesterol in all lipoprotein particles. HDL carries cholesterol away from tissues and is not considered atherogenic. LDL is the main atherogenic particle and the main treatment target. Non-HDL includes LDL plus the cholesterol in triglyceride-rich particles, so it captures risk that LDL can miss when triglycerides are high. Triglycerides reflect fat carried in VLDL and, after meals, in chylomicrons.

When triglycerides are normal, LDL and non-HDL tell a similar story, and non-HDL is usually about 30 mg/dL (0.8 mmol/L) higher than LDL. When triglycerides are high, non-HDL and apolipoprotein B become more informative, and the old Friedewald equation underestimates LDL – which is why our calculator uses the NIH equation.

Do you need to fast?

For most people, no. Non-fasting lipid panels are accepted by European and US guidance for routine assessment, because total cholesterol, HDL and non-HDL change little after a normal meal and triglycerides rise only modestly. Fasting may be requested if non-fasting triglycerides are above about 400 mg/dL (4.5 mmol/L).

What lowers cholesterol

Lifestyle measures – replacing saturated fat with unsaturated fat, more soluble fibre, weight loss where needed, regular activity and less alcohol and sugar – typically lower LDL and non-HDL by around 5–20%. Statins lower LDL by roughly 30–50% or more, and ezetimibe, PCSK9 inhibitors, inclisiran and bempedoic acid add further reductions. Whether treatment is recommended depends on your overall cardiovascular risk rather than any single number.

When to seek medical advice

Talk to a clinician if your LDL is 160 mg/dL (4.1 mmol/L) or higher, especially if it is 190 mg/dL (4.9 mmol/L) or higher, which may indicate familial hypercholesterolaemia; if your triglycerides are above 500 mg/dL (5.6 mmol/L); or if you have a family history of early heart disease. People with diabetes should also keep an eye on glucose control – our A1C calculator can help put results in context.