Ferritin Unit Converter
Ferritin Unit Converter
Convert serum ferritin between ng/mL, µg/L, µg/dL, nmol/L and pmol/L, and see instantly whether the value sits inside the reference interval.
Ferritin converter
Mass ⇄ molarFerritin 18 ng/mL
Formula and conversion factor
ng/mL = pmol/L ÷ 2.247
- 2.247
- conversion factor derived from an apoferritin molecular weight of ≈445,000 Da
- ng/mL
- identical in magnitude to µg/L — no arithmetic needed between them
- µg/dL
- ng/mL ÷ 10
Worked example
Ferritin 18 ng/mL
18 × 2.247 = 40.4 pmol/L
18 ng/mL = 18 µg/L = 1.80 µg/dL = 0.040 nmol/L
Reference ranges
| Group | ng/mL (µg/L) | pmol/L |
|---|---|---|
| Men, adult | 24 – 336 | 54 – 755 |
| Women, adult | 11 – 307 | 25 – 690 |
| Iron deficiency, likely | < 30 | < 67 |
| Iron deficiency with inflammation | < 100 | < 225 |
What ferritin measures
Ferritin is the body’s iron-storage protein, and the small fraction that circulates in serum is proportional to total body iron stores. That proportionality is what makes it the single most useful first-line test for iron deficiency: a low ferritin is the earliest laboratory abnormality in iron depletion, appearing well before haemoglobin falls or red cell indices change.
The interpretation is asymmetric. A low ferritin is close to diagnostic of iron deficiency and is rarely caused by anything else. A normal or raised ferritin does not exclude it, because ferritin is an acute-phase reactant — infection, chronic inflammation, liver disease, malignancy and heavy alcohol use all push it up independently of iron stores. This is why guidelines raise the diagnostic threshold to roughly 100 µg/L when C-reactive protein is elevated, and why ferritin is usually read alongside transferrin saturation rather than alone.
Very high ferritin has its own differential: haemochromatosis and iron overload, but also adult-onset Still’s disease, haemophagocytic lymphohistiocytosis and severe hepatocellular injury, where values in the thousands are common without any excess iron at all.
Frequently asked questions
Is ng/mL the same as µg/L for ferritin?
Yes — they are numerically identical, so a report of 18 ng/mL and one of 18 µg/L mean exactly the same thing. Laboratories in the United States tend to report ng/mL, while most of Europe and the SI convention use µg/L.
How do I convert ferritin to pmol/L?
Multiply the ng/mL value by 2.247. The factor comes from ferritin’s molecular weight of about 445,000 Da; because iron content varies the molecular weight is not perfectly fixed, so molar reporting of ferritin is uncommon in routine practice.
What ferritin level means iron deficiency?
Below 30 µg/L is generally accepted as iron deficiency in an otherwise well adult, and below 15 µg/L is close to specific for absent iron stores. If inflammation is present the threshold rises to around 100 µg/L, and transferrin saturation below 20% supports the diagnosis.
Can ferritin be high without iron overload?
Frequently. Ferritin rises in any inflammatory state, in liver disease, after alcohol, in malignancy and dramatically in haemophagocytic syndromes. A raised ferritin should prompt a transferrin saturation before iron overload is assumed.
Related calculators
References
- WHO. Serum ferritin concentrations for the assessment of iron status and iron deficiency in populations. Geneva, 2020.
- Camaschella C. Iron deficiency. Blood. 2019;133(1):30–39.
- Assay package insert — ferritin immunoassay, molecular weight and unit conversion.