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Free health tool

Folate unit converter

Convert an existing laboratory total folate concentration between ng/mL, µg/L and nmol/L without interpreting the result or converting between specimen types.

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Calculate your result

Which result are you converting?

Choose the specimen on the source report. This changes the result label only; it never converts serum or plasma folate into red-cell folate, or the reverse.

Enter the numeric total folate result exactly as reported. On this English page, use a full stop for decimals and do not enter a unit or thousands separator.

Accepted range: 0 to 10000 ng/mL total folate

Your result will appear here

Nothing is saved or added to the URL.

What this result means

Choose whether the laboratory result is serum or plasma total folate, or an already calculated red-cell folate result. Then choose the units and enter the reported number. The converter uses 1 ng/mL = 1 µg/L = 2.265 nmol/L. [1][3][4][5]

The concentration stays the same

Unit conversion changes how the laboratory concentration is written, not the sample or the amount measured. One ng/mL and one µg/L are dimensionally identical, and the conventional total-folate conversion expresses either mass unit as 2.265 nmol/L. [1][3][4]

Keep the specimen attached to the number

WHO treats serum or plasma folate and red-cell folate as distinct measures. They cannot be converted into one another with a unit factor. Choose red-cell folate only when the source report already gives the final red-cell concentration; laboratory calculation from whole blood may require haematocrit and other assay information. [2][4][5]

Why this version uses 2.265

CDC data documentation and current laboratory guides use 2.265 for total folate reported as a folic-acid equivalent. This calculator pins that factor so every conversion is reproducible and the reverse calculation uses the exact reciprocal 200/453. [1][3][4][5]

The factor does not apply to every folate molecule separately. CDC laboratory documentation lists different conversion factors for individual folate forms, so this tool accepts only a laboratory total-folate result reported under the conventional factor. [6]

How the answer is rounded

The calculator stores 2.265 as the exact fraction 453/200, uses 200/453 for the reverse, and rounds only the final display. It shows one decimal in nmol/L and two decimals in ng/mL or µg/L. These display digits explain the arithmetic but do not add precision to the source laboratory measurement. [1][3]

What the conversion cannot tell you

The converted number does not classify folate status, diagnose a deficiency or show what caused a result. Reference intervals, clinical decisions and pregnancy or treatment guidance are separate questions that depend on the original report, assay, health context and qualified professional advice. [2]

Safe next steps

Check the source report for the specimen, analyte name, original unit, assay note, reference interval and date. Keep those details beside the converted value. If the report names a specific folate form, supplies a whole-blood intermediate or uses a different stated factor, do not use this converter; follow the laboratory's own method information. [4][5][6]

Formula and assumptions

Formula
nmol/L = ng/mL × 2.265; ng/mL = nmol/L × 200 ÷ 453. One ng/mL equals one µg/L, so the same equations apply to µg/L. The specimen context never changes the arithmetic. [1][3][4][5]
Version
Total folate reporting-unit conversion, folate-folic-acid-equivalent-conversion-v1
Rounding
Use exact decimal arithmetic with 2.265 stored as 453/200 and its reciprocal as 200/453, then round once: one decimal for nmol/L and two decimals for ng/mL or µg/L. Exact halfway ties round upward in magnitude; a positive value below display resolution uses a less-than result.
Worked example
A serum total folate result of 7.0 ng/mL is also 7.0 µg/L. Using the pinned factor, 7 × 2.265 = 15.855 nmol/L, displayed as 15.9 nmol/L serum/plasma total folate. This is a unit equivalent, not a health classification. [1][3][4]

Who this is for — and when not to use it

Intended use

Neutral unit conversion for a person who already has a laboratory total folate concentration reported as serum, plasma or a final red-cell result in ng/mL, µg/L or nmol/L.

Not intended for

This tool does not interpret folate status, apply a deficiency threshold or reference range, diagnose a condition, convert between serum or plasma and red cells, calculate red-cell folate from whole blood and haematocrit, convert an individual folate form, or guide food, supplement, pregnancy or treatment dosing.

Exclusions

  • Folate-status interpretation, deficiency thresholds, reference ranges, targets and diagnosis
  • Conversion between serum or plasma folate and red-cell or erythrocyte folate
  • Whole-blood or haemolysate calculations requiring haematocrit or another laboratory input
  • Individual folate forms or vitamers, including 5-MTHF, 5-formylTHF, THF, unmetabolised folic acid and MeFox
  • Food folate, dietary folate equivalents, supplement labels, microgram doses and treatment dosing
  • MTHFR interpretation, pregnancy advice, symptoms, medication decisions or urgent-care decisions
  • Any analyte other than laboratory total folate
  • Changing or reconstructing precision absent from the original laboratory report

Evidence sources

  1. 1. NHANES 2015–2016 Data Documentation: Folate Forms — Total and Individual — National Center for Health Statistics, Centers for Disease Control and Prevention. Accessed Aug 17, 2026.
  2. 2. Serum and Red Blood Cell Folate Concentrations for Assessing Folate Status in Populations — World Health Organization. Accessed Aug 17, 2026.
  3. 3. Auckland Test Guide: Folate — Te Toka Tumai Auckland, Te Whatu Ora. Accessed Aug 17, 2026.
  4. 4. Folate, Serum/Plasma — In-Common Laboratories. Accessed Aug 17, 2026.
  5. 5. Folate, Erythrocytes — In-Common Laboratories. Accessed Aug 17, 2026.
  6. 6. NHANES 2015–2016 Laboratory Procedure Manual: Folate Forms — National Center for Health Statistics, Centers for Disease Control and Prevention. Accessed Aug 17, 2026.