Converter

Parts-Per Converter

Details

How to use Parts-Per Converter

What the tool does, how to run it, and what to expect from the result.

How to convert ppm, ppb, and percent

Type a value, choose the unit it is in, and choose the unit you want. Everything sits on a base-10 ladder from percent (10^-2) down to parts per trillion (10^-12), so every conversion is a shift of the decimal point.

The table shows all seven units at once. Note that mg/kg is exactly 1 ppm by mass, while mg/L is only equal to 1 ppm when the solution's density is about 1 kg per litre.

  • Enter the concentration value.
  • Choose the unit it is in: percent, per mille, ppm, ppb, ppt, mg/kg, or mg/L.
  • Choose the target unit.
  • Read the result, or scan the table for every unit at once.
  • Check whether your source uses ppt for trillion or for thousand before you trust the number.
Tips

Getting a better result out of Parts-Per Converter

Specific settings and thresholds, not general advice.

  • The whole ladder is powers of ten from 1: percent is 10^-2, per mille is 10^-3, ppm is 10^-6, ppb is 10^-9, ppt is 10^-12. So 1% is 10,000 ppm, and 1 ppm is 1000 ppb.
  • mg/kg is exactly 1 ppm by mass, and that identity is definitional: one milligram in one kilogram is one part in a million by weight. Soil, food, and sediment limits are quoted either way and they mean the same thing.
  • mg/L is only approximately 1 ppm, and the approximation depends on the solution having a density of about 1 kg/L. That holds for dilute water at room temperature. It does not hold for seawater, for concentrated solutions, or for solvents, and treating it as exact there will give you a systematic error.
  • ppt here means parts per trillion (10^-12), not parts per thousand. The abbreviation is genuinely ambiguous in the literature: some European sources use ppt for parts per thousand, which is per mille. Check which one your source means before you convert.
  • For gases, ppm by volume and ppm by mass are different numbers, because gases have different molar masses. This converter is a pure ratio converter and does not know which basis you are on.
Limits

What Parts-Per Converter does not do

The honest boundary, so you do not lose time finding it yourself.

  • Ratio conversion only. There is no molar-mass or molecular-weight input, so it cannot convert ppm to mg/m^3 for a gas.
  • mg/L is treated as exactly 1 ppm, which assumes a solution density of 1 kg/L.
  • It does not distinguish mass-basis from volume-basis concentrations.
  • Seven units only: percent, per mille, ppm, ppb, ppt, mg/kg, mg/L.
At a glance

Who Parts-Per Converter is for

A quick way to understand who this helps, what it solves, and where it connects next.

Best fit

Anyone converting concentration units.

Ideal for

Using the parts-per converter without installing anything or signing up.

FAQ

Common questions

Short answers for the questions people usually have before trying a utility like this.

How do I convert percent to ppm?

Multiply by 10,000. One percent is one part in a hundred, and one ppm is one part in a million, so 1% = 10,000 ppm, 0.1% = 1000 ppm, and 0.0001% = 1 ppm. It is the same ratio expressed against different denominators.

Is mg/L the same as ppm?

For dilute aqueous solutions, yes, and this converter treats them as equal. The equivalence rests on water having a density of about 1 kg per litre, so a milligram in a litre is a milligram in a kilogram, which is one part per million by mass. For seawater, brines, or non-aqueous solvents, the density is not 1 kg/L and the equivalence breaks down.

Does ppt mean parts per trillion or parts per thousand?

In this converter, parts per trillion (10^-12). But the abbreviation is genuinely contested: some sources, particularly older and European ones, use ppt for parts per thousand, which is what per mille means. Whenever you see ppt in a document, confirm which one is intended, because the two differ by a factor of a billion.

Can I convert ppm to mg/m^3 for a gas?

Not here. That conversion needs the substance's molar mass and the temperature and pressure, because ppm for a gas is normally a volume ratio while mg/m^3 is a mass concentration. This tool is a pure ratio converter, so it has no chemistry in it.

What is a real-world sense of scale for ppm and ppb?

One ppm is roughly one minute in two years, or a single drop of water in a 50-litre tank. One ppb is about one second in 32 years. Regulatory limits often live in these ranges: the EU limit for lead in drinking water is 10 micrograms per litre, which is 10 ppb.

Is per mille the same as per cent?

No. Per mille is per thousand, written with the symbol, and it is ten times larger a denominator than percent. 1 per mille is 0.1%, or 1000 ppm. It is used for blood alcohol content in much of Europe and for slopes and gradients in engineering.

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