What Was Your LDL Cholesterol Before Starting Statins?
If you’re already on a statin or other lipid-lowering therapy, your current LDL reading doesn’t reflect your true baseline. Use this calculator to back-calculate your pre-treatment LDL — useful for assessing cardiovascular risk, screening for familial hypercholesterolaemia, or reviewing your treatment targets.
LDL Cholesterol Back-Calculator
1
2
Enter value in mmol/L
3
Adjustment factors sourced from ACC/AHA and PBS data — see reference below
Estimated Pre-Treatment LDL-C
—
mmol/L
How Does This Calculator Work?
Each lipid-lowering medication reduces LDL by a predictable percentage. The adjustment factor is simply the mathematical reciprocal: divide 1 by (1 − fractional reduction). For example, atorvastatin 40 mg reduces LDL by approximately 50%, giving a factor of 1 ÷ 0.50 = ×2.0. Your current LDL is multiplied by this factor to estimate baseline.
Formula: Pre-treatment LDL = On-treatment LDL × adjustment factor
Important: These are population-average estimates. Individual response varies based on genetics, adherence, body weight, and concurrent medications. Results are approximations only and should not replace clinical assessment.
Adjustment Factors by Medication
| Medication | Approximate LDL Reduction | Adjustment Factor | Intensity |
|---|---|---|---|
| Atorvastatin 10 mg | ~35% | ×1.54 | Moderate |
| Atorvastatin 20 mg | ~45% | ×1.82 | Moderate |
| Atorvastatin 40 mg | ~50% | ×2.00 | High |
| Atorvastatin 80 mg | ~54% | ×2.17 | High |
| Rosuvastatin 5 mg | ~40% | ×1.67 | Low–Mod |
| Rosuvastatin 10 mg | ~50% | ×2.00 | High |
| Rosuvastatin 20–40 mg | ~55% | ×2.22 | High |
| Simvastatin 10–20 mg | ~30–35% | ×1.43–1.54 | Low |
| Simvastatin 40–80 mg | ~40–45% | ×1.67–1.82 | Moderate |
| Pravastatin 10–40 mg | ~20–30% | ×1.25–1.43 | Low |
| Ezetimibe 10 mg | ~20% | ×1.25 | Low |
| Statin + Ezetimibe (various) | ~45–72% | ×1.82–3.57 | High |
| Evolocumab 140 mg Q2W | ~70% | ×3.33 | Very High |
| Evolocumab 420 mg QM | ~75% | ×4.00 | Very High |
| Alirocumab 75–150 mg Q2W | ~70–74% | ×3.33–3.85 | Very High |
| PCSK9i + High-intensity statin | ~84–85% | ×6.25–6.67 | Very High |
| PCSK9i + Statin + Ezetimibe | ~89–90% | ×9.09–10.00 | Very High |
| Inclisiran 284 mg SC | ~54% | ×2.17 | High |
| Bempedoic acid 180 mg | ~18% | ×1.22 | Low |
| Bempedoic acid + Ezetimibe | ~33% | ×1.49 | Moderate |
Why Back-Calculate LDL?
Clinical Applications
- FH screening: A pre-treatment LDL ≥5.0 mmol/L (≥193 mg/dL) is a key diagnostic criterion for probable/definite FH. Patients often present already on statins.
- CVD risk reclassification: On-treatment LDL underestimates true lifetime exposure. Back-calculating allows more accurate risk stratification.
- Treatment target setting: Knowing baseline LDL helps estimate how much further reduction is needed to reach guideline targets (e.g. <1.4 mmol/L for very high risk).
- New patient assessment: When a patient transfers care already on therapy and no pre-treatment lipids are available.
- Coronary calcium score interpretation: CAC scores should be interpreted in the context of true baseline LDL burden.
Frequently Asked Questions
The adjustment factors reflect average population responses from large clinical trials (JUPITER, PROVE IT-TIMI 22, FOURIER, ORION-1 etc.). Individual response varies by ±15–30% due to genetics (e.g. CYP3A4 polymorphisms for atorvastatin, SLCO1B1 for rosuvastatin), body composition, and adherence. The result is a clinically useful approximation — not an exact measurement.
A pre-treatment LDL ≥5.0 mmol/L (≥193 mg/dL) warrants evaluation for Familial Hypercholesterolaemia. FH affects approximately 1 in 250 Australians and is substantially underdiagnosed. Use the FH Calculator alongside a clinical assessment and family history.
No. Stopping statins in a patient at elevated cardiovascular risk is not recommended just to obtain a baseline measurement. This calculator exists precisely to avoid that need. However, in genuinely low-risk individuals where the indication for a statin is being reviewed, a structured washout under medical supervision (typically 4–6 weeks for most statins) may occasionally be appropriate.
PCSK9 inhibitors (evolocumab, alirocumab) reduce LDL by 60–75% as monotherapy, and up to 85–90% when combined with a high-intensity statin and ezetimibe. Because the on-treatment LDL may be extremely low (sometimes <0.5 mmol/L), even a small absolute number represents a very high pre-treatment level. For example, an LDL of 0.6 mmol/L on triple therapy (factor ×10) would back-calculate to 6.0 mmol/L — firmly in the FH range.
Per the 2023 Australian CVD Risk Guidelines: very high risk (established ASCVD, diabetes with organ damage, CKD stage ≥4, FH with ASCVD) — target LDL <1.4 mmol/L; high risk — <1.8 mmol/L; moderate risk — <2.6 mmol/L. The ESC 2021 guidelines align closely. Note that targets apply to on-treatment LDL, not back-calculated baseline.
This calculator is specific to LDL-C. Statins also reduce total cholesterol, triglycerides, and ApoB to varying degrees, but the adjustment factors differ. Non-HDL-C back-calculation is also possible using similar methodology but requires a separate calculation. For ApoB, use our ApoB Unit Conversion tool.
References
- Mach F, et al. 2019 ESC/EAS Guidelines for the management of dyslipidaemias. Eur Heart J. 2020;41(1):111–188. doi:10.1093/eurheartj/ehz455
- Visseren FLJ, et al. 2021 ESC Guidelines on cardiovascular disease prevention in clinical practice. Eur Heart J. 2021;42(34):3227–3337. doi:10.1093/eurheartj/ehab484
- Mach F, Koskinas KC, et al. 2025 Focused Update of the 2019 ESC/EAS Guidelines for the management of dyslipidaemias. Eur Heart J. 2025. doi:10.1093/eurheartj/ehae895
- Grundy SM, et al. 2018 AHA/ACC/Multisociety Guideline on the Management of Blood Cholesterol. Circulation. 2019;139(25):e1082–e1143. doi:10.1161/CIR.0000000000000625
- Sabatine MS, et al. Evolocumab and Clinical Outcomes in Patients with Cardiovascular Disease (FOURIER). N Engl J Med. 2017;376:1713–1722. doi:10.1056/NEJMoa1615664
- Schwartz GG, et al. Alirocumab and Cardiovascular Outcomes after Acute Coronary Syndrome (ODYSSEY OUTCOMES). N Engl J Med. 2018;379:2097–2107. doi:10.1056/NEJMoa1801174
- Cannon CP, et al. Ezetimibe Added to Statin Therapy after Acute Coronary Syndromes (IMPROVE-IT). N Engl J Med. 2015;372:2387–2397. doi:10.1056/NEJMoa1410489
- Ray KK, et al. Two Phase 3 Trials of Inclisiran in Patients with Elevated LDL Cholesterol (ORION-10, ORION-11). N Engl J Med. 2020;382:1507–1519. doi:10.1056/NEJMoa1912387
- Nissen SE, et al. Bempedoic Acid and Cardiovascular Outcomes in Statin-Intolerant Patients (CLEAR Outcomes). N Engl J Med. 2023;388:1353–1364. doi:10.1056/NEJMoa2215024
See also: Familial Hypercholesterolaemia · Lipoprotein(a) Review · How to Prevent a Heart Attack · Coronary Calcium Score