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mg/kg to Percent Converter

↔ Convert % to mg/kg instead

Common Conversions

mg/kg %
1 0.0001
10 0.001
100 0.01
1000 0.1
5000 0.5
10000 1
25000 2.5
50000 5
100000 10
250000 25
500000 50
1000000 100

Why this conversion matters in chemistry

Brownfield-site work makes the boundary between scales explicit. EPA's residential RSL for lead in soil is 400 mg/kg, which is 0.04% w/w — the same number, just dressed for a different audience. The conversion goes the other way at higher concentrations: an ore feeding a smelter at 5% w/w writes as 50,000 mg/kg in the contamination-characterization spreadsheet. The arithmetic itself is just 10⁴ between the two scales — mg/kg sits at 10⁻⁶, percent at 10⁻², and the gap between them is the conversion factor.

Formula

% = mg/kg ÷ 10000

Worked Examples

10000 mg/kg = 1%

The conversion anchor — the boundary where ppm starts to feel cumbersome and percent takes over.

1 mg/kg = 0.0001%

1 ppm — the typical scale of EPA trace-contaminant thresholds.

100 mg/kg = 0.01%

100 ppm — about a quarter of the residential lead RSL.

50000 mg/kg = 5%

5% impurity — the kind of figure a bulk ore-grade or alloy-composition report writes.

Frequently Asked Questions

How do I convert mg/kg to %?
Divide by 10,000. So 5000 mg/kg becomes 0.5%. The factor is exact through the geometric ratio of the two scales.
Is mg/kg the same as ppm?
Yes, for mass per mass ratios. mg/kg = ppm by weight, by direct definition. The two notations describe the same trace-contamination quantity.
When is this conversion needed?
Geochemistry, food science, and materials-purity analysis where trace compositions are measured in mg/kg or ppm but reported in percent. The conversion is also routine in environmental site-assessment work bridging EPA cleanup thresholds and bulk-composition characterization.