BYTETOOLS

PPM Calculator

Convert between ppm, ppb, mg/L, mg/kg and percent by mass with a density field, plus a molarity bridge and a C1V1 = C2V2 dilution helper.

1 ppm
In ppm
1.0000e-6
As a mass fraction
1 g/mL
Density used

Every equivalent unit

ppm (parts per million, by mass)1
ppb (parts per billion, by mass)1,000
ppt (parts per trillion, by mass)1,000,000
% by mass1.0000e-4
mg/kg1
µg/g1
µg/kg1,000
mg/L1
µg/L1,000
g/L0.001
mg/mL0.001

ppm, ppb, mg/kg and % by mass are ratios of mass to mass, so they never need a density. mg/L, µg/L, g/L and mg/mL are mass per volume, so converting between the two families multiplies or divides by the solution density. At 1.000 g/mL — dilute water at room temperature — 1 mg/L and 1 ppm are the same number, which is why the two get used interchangeably in water testing.

What is the PPM Calculator?

Parts per million is a mass ratio: ppm equals mass of solute divided by mass of solution, times a million. In water at 1.000 g/mL, 1 mg/L equals 1 ppm — but in a denser solution the two numbers differ.

  • Eleven units converted at once, from ppt through to percent by mass
  • Density field so mass-per-volume and mass-per-mass units convert correctly
  • Molarity bridge in both directions, with molar mass parsed from a formula
  • C1V1 = C2V2 dilution solver with the diluent volume to add
  • Dilution factor reported alongside the answer
  • Runs entirely in the browser with no uploads

How to use the PPM Calculator

  1. 1

    Choose a mode: unit conversion, the ppm and molarity bridge, or a C1V1 = C2V2 dilution.

  2. 2

    For a conversion, type the concentration, pick the unit it is in, and set the solution density.

  3. 3

    Read the full table of equivalent units, all derived from the same mass fraction.

  4. 4

    In molarity mode, enter a formula or molar mass and convert in either direction.

  5. 5

    In dilution mode, pick the unknown and enter the other three values to get it.

About the PPM Calculator

The ByteTools PPM Calculator converts a concentration between eleven units — ppm, ppb, ppt, percent by mass, mg/kg, micrograms per gram and litre-based units like mg/L and g/L — and shows the whole set at once. Every value is converted through a mass fraction internally, which is what makes the density field matter: mass-per-mass units never need it, mass-per-volume units always do.

Two extra modes cover the jobs that usually follow. The molarity bridge converts between ppm and mol/L given a molar mass, which the tool can parse from a chemical formula, so 1 mM sodium chloride in water comes out as 58.44 ppm. The dilution helper solves C1V1 = C2V2 for any of the four terms and tells you how much solvent to add.

All the arithmetic runs in your browser and nothing is uploaded, so water-quality figures and lab data stay on your machine. The page also explains why mg/L and ppm are interchangeable in dilute water samples and where that shortcut breaks down.

Frequently asked questions

Is 1 ppm the same as 1 mg/L?

Only when the solution's density is 1.000 g/mL, which is close enough for dilute water samples at room temperature. ppm is a mass-to-mass ratio and mg/L is mass per volume, so in a brine or a solvent with a different density the two numbers pull apart.

How do you convert ppm to percent?

Divide by 10,000. One percent by mass is 10,000 ppm, so 250 ppm is 0.025 percent. Both are mass ratios, so no density is involved in that conversion.

How do you convert ppm to molarity?

Multiply the ppm figure by the solution density to get mg/L, then divide by the molar mass times 1000. Going the other way, molarity times molar mass times 1000, divided by density, gives ppm. This tool does both once you supply a formula or molar mass.

What is the difference between ppm and ppb?

A factor of a thousand. Parts per million is one part in 10 to the sixth, parts per billion is one in 10 to the ninth. Trace contaminants in drinking water are usually quoted in ppb because the ppm figures would be small decimals.

How do I dilute a stock solution to a target concentration?

Use C1V1 = C2V2. Multiply the concentration you want by the final volume, divide by the stock concentration, and that is the volume of stock to take. Top it up with solvent to the final volume — this tool reports that top-up amount directly.

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