Introduction
This LDL calculator finds your LDL cholesterol, often called the "bad" cholesterol, from a standard lipid panel. Just enter your total cholesterol, HDL cholesterol, and triglycerides. The tool does the math and shows your result in both mg/dL and mmol/L.
You can pick from three trusted formulas. The Friedewald formula is the classic one used by most labs. The Modified Friedewald formula works better when triglycerides are high. The Martin-Hopkins formula uses a table of 180 values to fine-tune the answer, so it is the most accurate choice and is set as the default.
Along with your number, you get a risk rating from Very Low to Very High, a color scale, a step-by-step breakdown of the math, and charts that compare all three formulas. High LDL can build up in your arteries and raise your risk of heart attack and stroke, so knowing your level matters. To see how your numbers translate into long-term risk, pair this tool with our ASCVD Risk Calculator or the Framingham Risk Calculator.
This tool is for learning only. Always talk to your doctor about your lab results and what they mean for you.
How to use our LDL Calculator
Enter three numbers from your lipid panel — total cholesterol, HDL, and triglycerides — and the calculator shows your estimated LDL cholesterol in mg/dL and mmol/L, your risk category, and the full math behind it.
Total Cholesterol (TC): Type the total cholesterol number from your blood test. A normal result is about 125–200 mg/dL (3.9–5.2 mmol/L).
HDL Cholesterol (HDL): Type your HDL, the "good" cholesterol. It must be lower than your total cholesterol. A normal result is about 40–100 mg/dL (1.55–4.01 mmol/L). The same two numbers also drive our Cholesterol Ratio Calculator.
Triglycerides (TG): Type your triglyceride level. For the best result, use a test taken after a 9–12 hour fast. A normal result is under 150 mg/dL (1.7 mmol/L). Triglycerides are also the key input for the VLDL Calculator.
Units (mg/dL or mmol/L): Pick the unit that matches your lab report. Tapping a unit button changes all three fields at once, so you never have to convert by hand. For other lab and measurement conversions, see our Unit Converter Calculator.
Estimation Formula: Choose Martin-Hopkins (the default and most exact), Friedewald, or Modified Friedewald. If your triglycerides are above 400 mg/dL, the tool warns you and suggests a better formula.
Calculate and Reset: Press Calculate to see your LDL result, gauge, charts, and step-by-step solution. Press Reset to clear every field and start over.
What Is LDL Cholesterol?
LDL stands for low-density lipoprotein. It is often called the "bad" cholesterol. LDL carries cholesterol through your blood. When there is too much of it, the extra cholesterol can stick to the walls of your arteries. Over time this build-up, called plaque, makes arteries narrow and stiff. That raises your risk of a heart attack or stroke. Keeping LDL low is one of the best ways to protect your heart. Blood pressure and rhythm matter too — the MAP Calculator, QTc Calculator, and CHA2DS2-VASc Calculator cover other parts of the cardiac picture.
How LDL Is Measured
A blood test called a lipid panel checks your fats. Most labs do not measure LDL directly. Instead, they measure three things and use math to estimate LDL:
- Total cholesterol (TC) – all the cholesterol in your blood.
- HDL cholesterol – the "good" cholesterol that clears fat out of your blood.
- Triglycerides (TG) – the main type of fat your body stores for energy.
Those three numbers are all you need to estimate LDL cholesterol. Lipids are usually drawn alongside other panels, so you may also want the A1c Calculator for blood sugar, the GFR Calculator for kidney function, or the AST ALT Ratio Calculator for liver enzymes.
The Three LDL Formulas
Different equations exist because triglycerides change how much cholesterol sits in VLDL particles. Each formula handles that differently.
- Friedewald Formula: LDL = TC − HDL − (TG ÷ 5). The oldest and most common method. It works well when triglycerides are normal, but it is not trusted above 400 mg/dL, and it can read too low when LDL is under 70 mg/dL.
- Modified Friedewald: LDL = (TC − HDL) × 0.9 − (TG × 0.1). A simple fix that works better when triglycerides are high.
- Martin-Hopkins: LDL = TC − HDL − (TG ÷ adjustable factor). Instead of always dividing by 5, it picks a number from a 180-cell table based on your triglycerides and non-HDL cholesterol. Studies show it is the most accurate of the three, so it is the default here.
Curious how far apart two of these estimates fall? Run them through the Percent Difference Calculator.
LDL Cholesterol Ranges
| LDL (mg/dL) | LDL (mmol/L) | What It Means |
|---|---|---|
| Under 70 | Under 1.81 | Very low – a goal for people at high heart risk |
| 70–99 | 1.81–2.56 | Optimal |
| 100–129 | 2.59–3.34 | Near optimal |
| 130–159 | 3.36–4.11 | Borderline high |
| 160–189 | 4.14–4.89 | High |
| 190 and up | 4.91 and up | Very high |
Your own target may be lower if you have diabetes, past heart trouble, or family high cholesterol. Ask your doctor what number fits you. For a broader view of your ten-year outlook, try the CVD Risk Calculator or the newer PREVENT Calculator.
Non-HDL Cholesterol
Non-HDL cholesterol is total cholesterol minus HDL. It counts every "bad" particle, not just LDL. Many doctors watch it closely, especially when triglycerides are high. A good goal is usually about 30 mg/dL above your LDL goal.
Fasting Matters
Triglycerides jump after you eat. For the most accurate estimate, blood should be drawn after a 9 to 12 hour fast. A non-fasting test can still be useful, but a high triglyceride reading can throw off the Friedewald result. If you time your meals around lab work, the Fasting Calculator can help you plan the window.
Ways to Lower LDL
- Eat less saturated fat from fatty meat, butter, and full-fat dairy. Cut out trans fats. Plan your fat, protein, and carb split with the Macro Calculator.
- Eat more fiber: oats, beans, fruit, and vegetables. Set a daily target with the Fiber Calculator.
- Move your body about 30 minutes most days. The Heart Rate Zone Calculator and Calories Burned Calculator help you train at the right effort.
- Reach and keep a healthy weight. Check where you stand with the BMI Calculator or Waist to Height Ratio Calculator, then set a plan using the Calorie Deficit Calculator.
- Stop smoking.
- Take statins or other medicine if your doctor prescribes them.
Unit Conversion
The United States reports cholesterol in mg/dL. Most other countries use mmol/L. To switch, divide cholesterol values by 38.67 and triglycerides by 88.57. Our Metric Conversion Calculator handles other unit swaps you may meet on a lab report.
This tool gives an estimate for learning only. It does not replace a blood test or advice from your doctor.