Convert parts per million (ppm), parts per billion (ppb), parts per trillion (ppt), parts per quadrillion (ppq) and percent in both directions — with exact math, show-your-work steps, and a water-quality mode for mg/L. Looking for PowerPoint? See the note below — this page is about the chemistry unit.
🔒 100% private — everything runs in your browser, nothing is uploaded| Unit | Meaning | Value |
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One unit of each rung, and what it means as a fraction. Every step down multiplies by exactly 1,000.
| 1 unit of… | = ppm | = ppb | = ppt | “1 in…” |
|---|---|---|---|---|
| 1 % | 10,000 | 10,000,000 | 10,000,000,000 | 1 in 100 |
| 1 ppm | 1 | 1,000 | 1,000,000 | 1 in 1,000,000 |
| 1 ppb | 0.001 | 1 | 1,000 | 1 in 1,000,000,000 |
| 1 ppt | 0.000001 | 0.001 | 1 | 1 in 1,000,000,000,000 |
| 1 ppq | 0.000000001 | 0.000001 | 0.001 | 1 in 1,000,000,000,000,000 |
This tool converts the dimensionless ratio scale only — percent, ppm, ppb, ppt, ppq. It does not convert mass/volume concentrations in general: the water tab covers mg/L, µg/L, ng/L, g/L for dilute water only (density ≈ 1 kg/L). Air concentrations like µg/m³ need molar mass, temperature and pressure, so ppm ↔ µg/m³ is out of scope here. General unit converters on this site handle other dimensions; this page is the specialist for parts-per notation.
Every conversion on this page is an exact power of ten. The engine never uses binary floating point for the conversion path: your input is kept as an exact decimal string and the decimal point is shifted by the difference of the unit exponents (percent = 10−2, ppm = 10−6, ppb = 10−9, ppt = 10−12, ppq = 10−15).
So 2.5 ppm → ppb shifts 10−6 to 10−9, i.e. × 103, giving exactly 2500 — never 2500.0000000000005. Rounding happens only at the display layer (scientific notation keeps 6 significant digits, half-up).
Direction rules: moving down the scale (percent → ppm → ppb → ppt → ppq) multiplies by 1,000 per rung — except percent → ppm, which is × 10,000 and is labeled as such. Moving up divides by the same factors. Negative inputs are rejected with an explanation: a concentration ratio cannot be below zero.
ppm means parts per million: 1 ppm = 1 part in 1,000,000. As a fraction that is 1/1,000,000, which equals 0.0001%. It is the standard unit for dilute concentrations such as contaminants in drinking water, pollutants in air, and trace chemicals in manufacturing.
Multiply by 1,000. Each step down the parts-per scale is a factor of 1,000, so 1 ppm = 1,000 ppb. Example: 2.5 ppm x 1,000 = 2,500 ppb.
Multiply by 1,000,000. You climb two rungs of the scale: ppm -> ppb (x 1,000), then ppb -> ppt (x 1,000 again), so 1 ppm = 1,000,000 ppt. Example: 3 ppm = 3,000,000 ppt.
Here, ppt means parts per trillion: 1 ppt = 1 part in 10^12. The abbreviation is genuinely ambiguous, so to be clear: this page is a chemistry concentration converter, not presentation software. If you were looking for Microsoft PowerPoint (.ppt / .pptx files), this tool is not what you need. One more wrinkle: oceanographers use ppt for parts per thousand when measuring seawater salinity - a different unit again. This converter uses the chemistry sense (parts per trillion) throughout.
Multiply by 10,000. Because 1% = 1/100 and 1 ppm = 1/1,000,000, one percent contains ten thousand ppm. Example: 0.5% x 10,000 = 5,000 ppm.
They are rungs of one scale, each 1,000x smaller than the previous: 1 ppm = 1,000 ppb = 1,000,000 ppt = 1,000,000,000 ppq. All are dimensionless ratios; the letters only mark which rung you are on. Going up the scale you divide by 1,000 per rung.
10,000 ppm. Calculation: 1% = 1/100, 1 ppm = 1/1,000,000, and (1/100) / (1/1,000,000) = 10,000.
In dilute water solutions, yes, approximately. One liter of water weighs about 1 kilogram, so 1 mg per liter is about 1 mg per 1,000,000 mg = 1 ppm. This is an approximation that assumes density ~1 kg/L; it does not apply to air, oils, or other solvents.
No. ppm, ppb and ppt are concentration ratios, so the smallest possible value is 0. This converter rejects negative inputs with an explanation instead of silently converting them.
Divide by 1,000. Going up the scale reverses the factor: 1 ppb = 0.001 ppm. Example: 750 ppb / 1,000 = 0.75 ppm.
ppq means parts per quadrillion: 1 ppq = 1 part in 10^15. It is one rung below parts per trillion (1 ppt = 1,000 ppq) and is used for ultra-trace measurements in analytical chemistry.
Very large or very small results are shown in scientific notation because plain decimals become unreadable (1.5 x 10^9 = 1,500,000,000). Use the display-mode selector to force plain grouped decimals or scientific notation if you prefer.
For dilute water they are interchangeable: drinking-water reports, aquariums and hydroponics use both. Laboratories usually report water contaminants in mg/L or ug/L, while environmental regulations often write limits in ppm or ppb. Use the water tab above for mg/L <-> ug/L <-> ng/L conversions.
No, and that boundary is deliberate. ug/m3 is mass per volume of air, and converting it to ppm requires the pollutant's molar mass plus temperature and pressure. This converter handles the dimensionless ratio scale (percent, ppm, ppb, ppt, ppq) and the dilute-water mg/L family only.
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