The ratios, and why they beat a single number
A ratio compares your "bad" cholesterol against the "good" HDL that clears it, which predicts heart risk better than LDL on its own. Because HDL is the denominator, a person with high LDL but high HDL can have a healthier ratio than someone with lower LDL and low HDL.
Same LDL, different risk
These two people have LDL just 50 points apart, yet the one with more HDL ends up in the safer band. The ratio, not the LDL, is what moves.
Longer bar means a worse LDL-to-HDL ratio. The lower-LDL person is actually the higher-risk one, because their HDL is too low to keep up.
Where the thresholds fall
| Category | TC / HDL | LDL / HDL | TG / HDL |
|---|---|---|---|
| Optimal | < 3.5 | < 2.0 | < 2.0 |
| Borderline | 3.5–5.0 | 2.0–3.5 | 2.0–4.0 |
| High | 5.0–7.0 | 3.5–5.0 | 4.0–6.0 |
| Very high | > 7.0 | > 5.0 | > 6.0 |
Guidelines put HDL targets higher for women (above 50 mg/dL) than for men (above 40). Non-HDL cholesterol — total minus HDL — is worth tracking too, especially with high triglycerides.
Common questions
What is a good total cholesterol to HDL ratio?
Under 3.5 is optimal and under 5.0 is acceptable. The ratio is your total cholesterol divided by your HDL, so raising HDL lowers it just as much as cutting total cholesterol does.
Can I have high LDL but still be low risk?
Yes. Risk tracks the ratios, not LDL alone. LDL 150 with HDL 75 is a ratio of 2.0, which is optimal, while LDL 100 with HDL 30 is 3.3. High HDL offsets a high LDL.
How is LDL estimated when it is not measured?
The Friedewald equation: LDL equals total cholesterol minus HDL minus triglycerides divided by 5 (using mg/dL). It loses accuracy once triglycerides pass about 150, and should not be used above 400.
