Calculate your cholesterol ratio from total and HDL cholesterol, or find the missing total cholesterol or HDL value in mg/dL or mmol/L.

Cholesterol Ratio Calculator

Enter any 2 values to calculate the missing variable

Cholesterol Ratio Formula

The cholesterol ratio is the total cholesterol value divided by the HDL cholesterol value. It is written as a total-to-HDL ratio.

Ratio = TC / HDL TC = Ratio * HDL HDL = TC / Ratio mg / dL = mmol / L * 38.67 mmol / L = mg / dL / 38.67
  • Ratio = cholesterol ratio, written as total cholesterol to HDL cholesterol
  • TC = total cholesterol
  • HDL = high-density lipoprotein cholesterol
  • mg/dL = milligrams per deciliter
  • mmol/L = millimoles per liter

If you enter total cholesterol and HDL cholesterol, the calculator divides total cholesterol by HDL to find the ratio. If you enter HDL and the ratio, it multiplies them to find total cholesterol. If you enter total cholesterol and the ratio, it divides total cholesterol by the ratio to find HDL.

The ratio is unitless. Total cholesterol and HDL must be in comparable units before the ratio is calculated. The calculator supports both mg/dL and mmol/L.

Cholesterol Ratio Result Ranges

Cholesterol ratio ranges are general reference points. Your full lipid panel, age, blood pressure, diabetes status, smoking status, and medical history also matter.

Total:HDL Ratio General Meaning
Below 3.5 Often considered favorable
3.5 to 5.0 Common range, may need review with other risk factors
Above 5.0 May indicate higher cardiovascular risk

Common Cholesterol Unit Conversions

Cholesterol Value Equivalent Value
100 mg/dL 2.59 mmol/L
150 mg/dL 3.88 mmol/L
200 mg/dL 5.17 mmol/L
250 mg/dL 6.47 mmol/L

Example Calculations

Example 1: Find cholesterol ratio

You have total cholesterol of 200 mg/dL and HDL cholesterol of 50 mg/dL.

Ratio = 200 / 50 = 4.0

The cholesterol ratio is 4.0.

Example 2: Find HDL cholesterol

You have total cholesterol of 180 mg/dL and a cholesterol ratio of 3.6.

HDL = 180 / 3.6 = 50 mg / dL

The HDL cholesterol value is 50 mg/dL.

FAQ

What is a good cholesterol ratio?

A lower total-to-HDL cholesterol ratio is generally better. A ratio below 3.5 is often considered favorable, while a ratio above 5.0 may suggest higher cardiovascular risk. The ratio should not be used alone to judge heart risk.

Why does HDL affect the cholesterol ratio so much?

HDL is often called “good” cholesterol because higher HDL is generally associated with lower cardiovascular risk. Since HDL is the denominator in the ratio, a higher HDL value lowers the total-to-HDL ratio.

Can I compare mg/dL and mmol/L values directly?

No. Total cholesterol and HDL should be in the same unit system before calculating the ratio. If one value is in mg/dL and the other is in mmol/L, convert one of them first. For cholesterol, 1 mmol/L is about 38.67 mg/dL.