GIFSQ Tools · Module 1 — Food Composition & Proximate Analysis · Tool 17 of 500
Convert a mass fraction between % w/w, g/kg, mg/g, mg/kg (ppm) and µg/g. Enter the value and the two units.
Try sample values — fills the form with the worked example below.
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Converted value
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Canonical value (mg/kg)
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Entered value
Equation: Canonical unit mg/kg: % w/w × 10,000 = mg/kg; g/kg × 1,000 = mg/kg; mg/g × 1,000 = mg/kg; µg/g × 1 = mg/kg.
Converted value = canonical mg/kg ÷ factor of the target unit.
Method: Mass fraction definitions, SI: 1 % w/w = 10,000 mg/kg; 1 mg/kg = 1 ppm by mass (IUPAC).
Assumptions: the fraction is by mass throughout — a % w/v or mg/L value needs a density before it can be converted here.
Limitations: ppm by mass (mg/kg) and ppm by volume are not the same; do not use this converter for a gas or a solution given in mg/L without a density.
Rounding: results to 2 decimal places, except mg/kg shown to 2 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Converted value = canonical mg/kg ÷ factor of the target unit.
Method: Mass fraction definitions, SI: 1 % w/w = 10,000 mg/kg; 1 mg/kg = 1 ppm by mass (IUPAC).
Assumptions: the fraction is by mass throughout — a % w/v or mg/L value needs a density before it can be converted here.
Limitations: ppm by mass (mg/kg) and ppm by volume are not the same; do not use this converter for a gas or a solution given in mg/L without a density.
Rounding: results to 2 decimal places, except mg/kg shown to 2 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: Salt 2.50 % w/w. In mg/kg: 2.50 × 10,000 = 25,000.00 mg/kg (25,000 ppm). Back the other way, 500 mg/kg ÷ 10,000 = 0.05 % w/w.
Enter values above to see results.
1 % = 10,000 ppm. Use mg/kg (ppm) for trace levels such as residues and contaminants, and % w/w for major components such as salt and sugar. Tool 17 of 500 — GIFSQ
