Phosphate (as phosphorus) mg/dL → mmol/L
Convert phosphate (as phosphorus) from mg/dL to mmol/L
Sources last checked: 2026-11-03
Phosphate (as phosphorus) mg/dL → mmol/L
Convert phosphate (as phosphorus) from mg/dL to mmol/L
Converts units only; reference ranges depend on the laboratory, the assay and the patient.
What is the Phosphate (as phosphorus) mg/dL → mmol/L?
Serum inorganic phosphate is measured as its phosphorus content. In mg/dL — the unit in Turkey, the USA and some German and Austrian labs — the number means milligrams of phosphorus, so the conversion to mmol/L (used in many European labs and in UK guidance) multiplies by 0.3229, i.e. 10 ÷ the atomic mass of phosphorus (30.974 g/mol).
When to use it
- Comparing a mg/dL phosphate result with CKD-mineral bone disorder literature in mmol/L
- Converting before calculating a calcium × phosphate product in SI units
- Reading reports from countries that use different units
When not to use it
- Calculating with the molar mass of the whole phosphate ion (PO₄) — lab mg/dL values refer to phosphorus, and using the ion's mass gives a value that is far too low
- mEq/L values — the charge of phosphate depends on pH, so mEq/L is not a fixed multiple of mmol/L
- Interpreting the value: reference ranges are age-dependent (higher in children) and lab-specific
How it is calculated
Phosphate (mmol/L) = phosphate as phosphorus (mg/dL) × 0.3229
Clinical pearls and limitations
- Converts units only; reference ranges depend on the laboratory, the assay and the patient.
- 'Phosphate', 'phosphorus' and 'inorganic phosphate' on lab reports usually describe the same test; in mmol/L they give the same number, because one phosphate contains one phosphorus atom.
- Haemolysis and delayed separation of the sample raise phosphate.
- Phosphate shows a diurnal rhythm and changes after meals; serial values are best compared at similar times.
- Products such as calcium × phosphate must be computed with both values in the same unit system; the number changes with the units.
Frequently asked questions
How do I convert phosphate from mg/dL to mmol/L?
Multiply by 0.3229. For example, 3.5 mg/dL × 0.3229 = 1.13 mmol/L.
What is 5.5 mg/dL phosphorus in mmol/L?
5.5 × 0.3229 = 1.776, about 1.78 mmol/L.
Is serum phosphorus the same as serum phosphate?
Clinically yes: the lab measures inorganic phosphate and expresses the mass as phosphorus. That is why the factor uses phosphorus (30.974 g/mol).
Evidence and guidelines
Have a follow-up question?
Medelix answers clinical questions from current guidelines and studies — every statement with its source.
Related calculators
- Phosphate (as phosphorus) mmol/L → mg/dLConvert phosphate (as phosphorus) from mmol/L to mg/dL
- Calcium mmol/L → mg/dLConvert total or ionised calcium from mmol/L to mg/dL
- Magnesium mg/dL → mmol/LConvert magnesium from mg/dL to mmol/L
- eGFR (CKD-EPI 2021)Estimated glomerular filtration rate, race-free equation
Embed this calculatorFree to use on your website, intranet or teaching page. Copy the code below.
<iframe src="https://medelix.ai/en/embed/phosphate-mgdl-to-mmol" title="Phosphate (as phosphorus) mg/dL → mmol/L – Medelix" width="100%" height="620" style="border:0;max-width:720px" loading="lazy"></iframe>
<p><a href="https://medelix.ai/en/calculators/phosphate-mg-dl-to-mmol-l">Phosphate (as phosphorus) mg/dL → mmol/L calculator by Medelix</a></p>For healthcare professionals and medical students. These tools support, and do not replace, clinical judgement. Always check results against the original source and your local protocols.