Units on lab reports: ppm, ppb, mg/kg, per serving

Units at a glance

Key conversions

• 1 mg/kg = 1 ppm = 1 µg/gThe same concentration.
• 1 mg/kg = 1,000 µg/kgSo 0.1 mg/kg = 100 µg/kg.
• 1 µg/kg = 1 ppbUsed for very low levels.
• 1% = 10,000 mg/kgUsed for major components such as fulvic acid.

A simpler introduction to the three concentration units is in how to understand ppm, ppb and mg/kg.

From concentration to daily amount

Per-serving results

Some certificates report per serving. A Eurofins certificate published by Nature Elixirs gives arsenic as 0.213 µg, cadmium as 0.0146 µg and lead as 0.0367 µg per 0.5 mL serving.^[2] These numbers look tiny because a serving is small. To compare them with mg/kg limits, you need the serving’s weight in grams: divide the micrograms by the grams to get µg/g, which equals mg/kg. Without the serving weight and basis, a direct comparison isn’t possible. Nature Elixirs is a brand evaluated by Best Shilajit UK. Read our evaluation to see the evidence and documentation we reviewed.

As sold vs dry weight

Results can be expressed on the product as sold, or on a dry-weight basis that excludes moisture. Dry-weight figures are higher. GB supplement limits apply to the product as sold,^[1] so check the basis before comparing; see processing and composition.

Microbiology units

Microbiology results use cfu/g, or “absent” or “not detected” in a stated sample size, such as 25 g. “< 10 cfu/g” means below the method’s reporting limit; see microbiological testing.

Percentages for composition

Composition results, such as fulvic acid, are usually percentages. A percentage depends on the method and basis, so figures from different laboratories may not compare; see fulvic acid testing.

Common unit mistakes

• Mixing mg/kg and µg/kgA thousand-fold difference.
• Comparing per-serving with mg/kg limitsDifferent bases.
• Ignoring dry-weight basisInflates or deflates comparisons.
• Reading “<” as zeroIt means below a limit; see detection limits.

Scientific notation and decimals

Some reports use scientific notation, such as 1.5E-02, which means 0.015. Others use a comma as the decimal separator, especially laboratories in continental Europe, so 0,70 means 0.70. Read carefully to avoid misplacing a decimal point.

Finding the serving weight

To convert per-serving results, you need the serving weight in grams. For resin, that is your weighed serving; for liquids, you also need the liquid’s density to convert millilitres to grams. If the certificate doesn’t give the serving weight, ask the brand.

Putting it into practice

When you read a report, first identify the unit for each result, then check the basis (as sold or dry weight), then compare metals in mg/kg with GB limits, and finally multiply by your serving in grams to see daily amounts. Keep the conversion table above handy until it becomes second nature.

Liquid products

Liquid shilajit products are measured by volume, so certificates may report per millilitre or per serving in millilitres. To compare with mg/kg limits, you need both the serving volume and the liquid’s density, which converts millilitres to grams. Without those, compare liquids only with other figures on the same basis. If in doubt, ask the brand to express metals results in mg/kg as sold, which makes comparison with the GB limits straightforward. Clear units make a report far easier to trust, and a brand that presents its results consistently is usually one that understands them. It also makes comparing products, and checking your own daily intake, much simpler. If a report mixes units without explanation, ask the brand to clarify before relying on it. A careful brand will happily restate its results in a consistent unit and basis, so you can compare them properly with the legal limits.

The bottom line

mg/kg equals ppm, µg/kg equals ppb, and 1 mg/kg is 1,000 µg/kg. Compare metals with GB limits in mg/kg as sold, convert per-serving figures only when you know the serving weight, and multiply mg/kg by your serving in grams to see daily exposure.

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