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PPM Concentration Calculator

Five milligrams in two liters gives 2.5 mg/L. If the solution density is approximately 1 kg/L, that is approximately 2.5 ppm by mass, or 2,500 ppb. One percent by mass is 10,000 ppm by mass.

The calculator does not determine a drinking-water limit, a chemical dose or a safe concentration.

PPM Concentration Calculator: inputs

Calculated result
Parts per million (ppm)2.5
Parts per billion (ppb)2,500

PPM Concentration Calculator: Solute (milligrams) sensitivity

PPM Concentration Calculator: Solute (milligrams) and Parts per million (ppm)5 calculations vary the “Solute (milligrams)” input while holding the other entered inputs constant.424.52.352.55.52.863

PPM Concentration: worked example

Solute (milligrams)5
Solution volume (liters)2
Parts per million (ppm)2.5
Parts per billion (ppb)2,500

Common error: Mixing up ppm with percent. One percent is 10,000 ppm, so a ppm figure treated as a percent is off by four orders of magnitude.

PPM Concentration: formula

ppm = milligrams of solute ÷ liters of solution (for dilute water solutions); ppb = ppm × 1,000

OpenStax Chemistry: concentration

The equivalence with mg/L holds only for dilute aqueous solutions with a density near 1. For gases, ppm often means by volume, which is different. Different reports use ppm, mg/L and micrograms per liter, so check the units.

Analytical error at low levels can be large.

Enter the mass of the solute in milligrams and the volume of the solution in liters. For dilute water solutions, one liter of water weighs about one kilogram, so milligrams per liter equals parts per million. The tool also converts to parts per billion by multiplying by 1,000.

Use this for water quality figures such as chlorine, fluoride, nitrates and minerals, reported on lab and utility reports.

PPM Concentration: changing Solute (milligrams)

Solute (milligrams)Parts per million (ppm)Parts per billion (ppb)
422,000
4.52.32,250
5 (example)2.52,500
5.52.82,750
633,000

PPM Concentration: compare input ranges

InputTested fromToParts per million (ppm): low inputParts per million (ppm): high inputSwing
Solution volume (liters)1.82.22.82.30.505 (20%)
Solute (milligrams)4.55.52.32.80.5 (20%)

PPM Concentration: individual input comparisons

InputValueParts per million (ppm)Parts per billion (ppb)
Solute (milligrams)422,000
4.52.32,250
52.52,500
5.52.82,750
633,000
Solution volume (liters)1.63.13,125
1.82.82,777.8
22.52,500
2.22.32,272.7
2.42.12,083.3

PPM Concentration: combined input changes

Solute (milligrams) / Solution volume (liters)1.622.4
42.521.7
4.52.82.31.9
53.12.52.1
5.53.42.82.3
63.832.5

PPM Concentration: which assumptions move the result?

PPM Concentration: Parts per million (ppm) as Solution volume (liters) changesParts per million (ppm) starts at 3.1. Moving Solution volume (liters) from 1.6 to 2.4 changes it to 2.1, with Solute (milligrams) 5 kept fixed.1.63.11.82.822.52.22.32.42.1
Chart quantityDisplayed settings
Solution volume (liters)1.6 → 2.4
Parts per million (ppm)3.1 → 2.1
Solute (milligrams)5
PPM Concentration: Parts per million (ppm) as Solute (milligrams) changesParts per million (ppm) starts at 2. Moving Solute (milligrams) from 4 to 6 changes it to 3, with Solution volume (liters) 2 kept fixed.424.52.352.55.52.863
Chart quantityDisplayed settings
Solute (milligrams)4 → 6
Parts per million (ppm)2 → 3
Solution volume (liters)2

PPM Concentration: values and definitions

Quantity and definitionValue used
Solute (milligrams)5
Solution volume (liters)2
Parts per million (ppm)2.5
Parts per billion (ppb)2,500

PPM Concentration: half and double Solution volume (liters)

Solution volume (liters)Parts per million (ppm)
15
22.5
41.3

Science & Electronics calculators: Ohm's Law Calculator, Density Calculator, Molarity Calculator, Voltage Drop Calculator, Dilution Calculator, pH Value Calculator.

Parts per million expresses a trace amount as a ratio, and for dilute water solutions one milligram in a liter is one part per million. Five milligrams in two liters is 2.5 ppm, or 2,500 parts per billion. Water tests, garden fertilizer labels and pool chemistry all use it because the raw quantities are too small to be readable as percentages.

The equivalence rests on a liter of water weighing about a kilogram.

Confirm the solution is mostly water and dilute. Thick or non-aqueous solutions have a density that changes the conversion.

Prepare solutions on the molarity and dilution calculators, see pH on the pH page, and convert volumes on the volume converter. The percentage and scientific notation calculators help with small numbers, and the pool volume and rainwater pages relate to water treatment.

Does ppm always mean a mass fraction?

No. Gas reports can use mole or volume fractions. Establish the report’s convention before comparing it with this dilute-water calculation.

What does ppm mean?

Parts per million states a ratio with a multiplier of one million; identify whether the basis is mass, volume or another quantity. For a dilute aqueous solution assumed to have density 1 kg/L, mg/L approximately equals ppm by mass. The equivalence does not automatically extend to other densities or gas conventions.

How do I convert ppm to percent?

Divide by 10,000. So 10,000 ppm is 1%, and 1 ppm is 0.0001%.

Is ppm the same as mg/L?

For dilute water solutions, yes, since a liter of water weighs about a kilogram. For other liquids and gases the relationship differs.