--- title: Lab Test Unit Converter type: tool url: "https://www.test-well.com/tools/lab-unit-converter" mcp_tool: "convert_units" date_published: 2026-09-05 free: true --- # Lab Test Unit Converter > Choose the analyte, type your value, and the converter switches between US conventional units and SI units using the standard published factors — for example glucose mg/dL × 0.0555 = mmol/L, and total testosterone ng/dL × 0.0347 = nmol/L. Hemoglobin A1c uses the NGSP-to-IFCC master equation instead of a simple multiplier. ## Key facts | Fact | Value | | --- | --- | | Analytes | 30 | | Directions | US ↔ SI | | Method | Published factors | | Cost | Free | ## Conversion factors | Analyte | US unit | SI unit | US → SI multiply by | | --- | --- | --- | --- | | Glucose | mg/dL | mmol/L | 0.0555 | | Total cholesterol | mg/dL | mmol/L | 0.02586 | | LDL cholesterol | mg/dL | mmol/L | 0.02586 | | HDL cholesterol | mg/dL | mmol/L | 0.02586 | | Triglycerides | mg/dL | mmol/L | 0.01129 | | Testosterone (total) | ng/dL | nmol/L | 0.03467 | | Free testosterone | pg/mL | pmol/L | 3.467 (1 pg/mL = 0.1 ng/dL) | | Estradiol | pg/mL | pmol/L | 3.671 | | Progesterone | ng/mL | nmol/L | 3.18 | | Prolactin | ng/mL | mIU/L | 21.2 (WHO 3rd international standard) | | Cortisol | µg/dL | nmol/L | 27.59 | | DHEA-S | µg/dL | µmol/L | 0.02714 | | Vitamin D, 25-hydroxy | ng/mL | nmol/L | 2.496 | | Vitamin B12 | pg/mL | pmol/L | 0.7378 | | Folate | ng/mL | nmol/L | 2.266 | | Ferritin | ng/mL | µg/L | 1 (Same number, different label) | | Iron | µg/dL | µmol/L | 0.179 | | Creatinine | mg/dL | µmol/L | 88.42 | | BUN (urea nitrogen) | mg/dL | mmol/L | 0.357 (Converts to urea in mmol/L) | | Uric acid | mg/dL | µmol/L | 59.48 | | Calcium | mg/dL | mmol/L | 0.2495 | | Magnesium | mg/dL | mmol/L | 0.4114 | | Phosphorus | mg/dL | mmol/L | 0.3229 | | Bilirubin (total) | mg/dL | µmol/L | 17.1 | | Albumin | g/dL | g/L | 10 | | Hemoglobin | g/dL | g/L | 10 | | Insulin | µIU/mL | pmol/L | 6.945 | | TSH | µIU/mL | mIU/L | 1 (Same number, different label) | | PSA | ng/mL | µg/L | 1 (Same number, different label) | | C-reactive protein | mg/L | mg/dL | 0.1 | Hemoglobin A1c is not a unit swap: IFCC mmol/mol = (NGSP % − 2.15) × 10.929; estimated average glucose (mg/dL) = 28.7 × A1c − 46.7. ## For agents The same computation is exposed as the MCP tool `convert_units` at https://www.test-well.com/mcp and documented in https://www.test-well.com/openapi.json. ## Frequently asked questions ### Why do US and international labs use different units? US labs report most chemistry in mass-per-volume 'conventional' units (mg/dL, ng/mL). Most other countries and the research literature use SI molar units (mmol/L, nmol/L), which count molecules rather than mass. The conversion factor is fixed for each analyte because it comes from its molecular weight. ### How do I convert hemoglobin A1c from % to mmol/mol? A1c isn't a unit swap — the two scales are different standardizations. Use the NGSP/IFCC master equation: mmol/mol = (A1c% − 2.15) × 10.929. So 5.7% ≈ 39 mmol/mol and 6.5% ≈ 48 mmol/mol. The tool also shows estimated average glucose (eAG = 28.7 × A1c − 46.7 mg/dL). ### Does converting units change whether my result is normal? No. The value and the reference range convert by the same factor, so a result inside the range in mg/dL is inside the equivalent range in mmol/L. Just make sure you compare against a range expressed in the same unit. ### Why is Lp(a) missing? Lipoprotein(a) mass (mg/dL) and particle number (nmol/L) don't have a fixed conversion — the ratio depends on the size of the apo(a) isoform and varies between people. Guidelines now recommend reporting Lp(a) in nmol/L, so compare like with like rather than converting. ## Related - [glucose](https://www.test-well.com/biomarkers/glucose) - [total cholesterol](https://www.test-well.com/biomarkers/total-cholesterol) - [total testosterone](https://www.test-well.com/biomarkers/total-testosterone) - [vitamin d 25 hydroxy](https://www.test-well.com/biomarkers/vitamin-d-25-hydroxy) - [hemoglobin a1c](https://www.test-well.com/biomarkers/hemoglobin-a1c) - [creatinine](https://www.test-well.com/biomarkers/creatinine) - [comprehensive metabolic panel](https://www.test-well.com/tests/comprehensive-metabolic-panel) - [lipid panel](https://www.test-well.com/tests/lipid-panel) --- Canonical page: https://www.test-well.com/tools/lab-unit-converter Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.