Concentration Converter
ScienceConvert concentration units between ppm, ppb, percent, mg/L, and g/L — used for water quality testing, chemistry, and lab dilution calculations.
From
To
All conversionsfor 1 Parts per Million (ppm)
| Percent (%) | 0.0001 |
| Per Mille (‰) | 0.001 |
| Parts per Million (ppm) | 1 |
| Parts per Billion (ppb) | 1000 |
| Parts per Trillion (ppt) | 1000000 |
| Milligrams per Litre (mg/L) | 1 |
| Grams per Litre (g/L) | 0.001 |
| Micrograms per Litre (µg/L) | 1000 |
| Milligrams per Kilogram (mg/kg) | 1 |
What is a Concentration?
The Concentration Converter converts between the units used to express how much of a substance is present in a mixture or solution — percent, per mille, ppm, ppb, ppt, and the mass-per-volume units mg/L, g/L, and µg/L. These units span an enormous range of scale: percent handles concentrations from 1 part in 100, while ppt (parts per trillion) handles concentrations as dilute as 1 part in a trillion, both describing the same underlying idea of "how much of this substance is in the total."
For dilute aqueous (water-based) solutions — the overwhelming majority of environmental, water-quality, and lab reporting contexts — this converter applies the standard approximation that 1 mg/L equals 1 ppm, since water's density is close enough to 1 kilogram per litre for the two units to be treated as numerically equivalent. If your work also involves solution density outside this approximation, the Density Converter handles general mass-per-volume conversions.
How to use this Concentration calculator
- Choose your starting unit from the source dropdown — for example, "Parts per Million (ppm)".
- Enter the numeric concentration value in the input field.
- Choose your target unit from the destination dropdown — for example, "Milligrams per Litre (mg/L)".
- Read the converted result, which updates instantly as you type or change units.
- Use the swap (⇅) button if you need to reverse the conversion direction.
- Use the copy button to grab the result for a lab report, water test log, or dilution worksheet.
Formula & Methodology
The converter's base unit is ppm (parts per million). Every ratio-based unit has a fixed multiplier to ppm: - 1 percent (%) = 10,000 ppm - 1 per mille (‰) = 1,000 ppm - 1 ppb = 0.001 ppm - 1 ppt = 0.000001 ppm For aqueous mass-per-volume units, the standard dilute-solution approximation (density ≈ 1 kg/L) treats: - 1 mg/L ≈ 1 ppm - 1 g/L ≈ 1,000 ppm - 1 µg/L ≈ 0.001 ppm Any conversion follows: Result = Input × (toBase of source unit ÷ toBase of target unit) Worked example — converting 250 ppm to percent: Result = 250 × (1 ÷ 10,000) = 0.025% This confirms that even a concentration considered notably high in ppm terms (250 ppm) corresponds to a small percentage — a useful sanity check when switching between the two units on a lab report.
Frequently Asked Questions
PPM stands for 'parts per million' and represents a ratio of one part of a substance to one million parts of the total solution or mixture, by mass. It's a way of expressing very small concentrations without writing out a lot of decimal places, and it's the standard unit for reporting trace contaminants in water, air, and soil.
For dilute aqueous (water-based) solutions, 1 ppm is approximately equal to 1 mg/L, because water's density is very close to 1 kilogram per litre. Enter your ppm value with 'Parts per Million (ppm)' as the source and 'Milligrams per Litre (mg/L)' as the target to see this 1:1 relationship applied directly.
No — the 1:1 approximation only holds precisely for dilute solutions where water is the primary solvent and its density is close to 1 kg/L, which covers the vast majority of water-quality and environmental testing use cases. For concentrated solutions, non-aqueous solvents, or situations where solution density deviates meaningfully from 1 kg/L, the true mg/L value differs from ppm and requires the actual solution density to convert accurately.
Divide the ppm value by 10,000 to get percent, since 1% equals 10,000 ppm. Enter your ppm value with 'Percent (%)' as the target unit and the converter applies this automatically.
PPB (parts per billion) is a thousand times smaller than ppm — 1 ppm equals 1,000 ppb. PPB is used when concentrations are too small to conveniently express in ppm, such as certain trace contaminants in drinking water regulated at sub-ppm thresholds.
Multiply the percent value by 10,000, since 1% equals 10,000 ppm. Enter your value with 'Percent (%)' as the source unit and 'Parts per Million (ppm)' as the target to get the result instantly.
Mg/L measures mass of solute per litre of solution (a volume-based measurement), while mg/kg measures mass of solute per kilogram of the total mixture (a mass-based measurement, also called a true mass fraction). For dilute aqueous solutions these are numerically almost identical because a litre of water weighs almost exactly one kilogram, which is why both are commonly treated as equivalent to ppm.
Safe thresholds vary by contaminant and regulatory body — for example, the EPA sets a maximum of 10 ppm for nitrate in US drinking water, while lead is regulated at levels in the low ppb range. This converter helps translate lab results reported in one unit (like µg/L) into the unit used in a specific regulation (like ppb), but always check the exact regulatory limit for the specific contaminant in question.
Lab technicians preparing standard solutions or diluting stock reagents often need to convert between percent concentration (common on reagent labels) and ppm or mg/L (common in analytical reporting) to calculate the correct dilution ratio. This converter handles that unit translation instantly so the technician can focus on the dilution formula itself.
Per mille (‰) represents parts per thousand and sits between percent (parts per hundred) and ppm (parts per million) on the ratio scale — it's less common in English-language contexts but appears in some European technical and food-labelling standards. Including it avoids a manual percent-to-ppm-to-permille conversion chain.
Also known as