Calculator
What the Parts Per Million Converter does
Parts Per Million Converter: 1 ppm = 1000 ppb, so multiply a parts per million value by 1000 to get parts per billion, or divide to go back. Example: 100 ppm = 100000 ppb.
From Value, From and To, this tool derives Result, How it was calculated and Reverse conversion. Edit a field and the answer updates in place.
Typical users are people following a recipe or spec written elsewhere. Two industries often use the same word for slightly different quantities.
There is no back end here. The calculation runs where you are sitting, not on a server somewhere.
The method, a field-by-field reference and a worked example built from the defaults are all on this page.
What do the Parts Per Million Converter fields mean?
The Parts Per Million Converter uses 3 inputs. Each input has a default that makes sense on its own, so a partial edit still gives a valid result.
| Field | What to enter | Default |
|---|---|---|
| Value | required | 100 |
| From | choose from Parts per million (ppm), Parts per billion (ppb), Parts per trillion (ppt), Percent (%), Per mille (‰) or Milligram per litre (in water) (mg/L) | Parts per million (ppm) |
| To | choose from Parts per million (ppm), Parts per billion (ppb), Parts per trillion (ppt), Percent (%), Per mille (‰) or Milligram per litre (in water) (mg/L) | Parts per billion (ppb) |
How does the Parts Per Million Converter work?
Both units are converted through concentration's base unit (ppm), so any of the 6 units in the dropdowns can be paired in either direction without loss of accuracy.
Factors follow the internationally agreed definitions. The inch has been exactly 25.4 mm since 1959, and an exact definition is used wherever one exists. Where a unit is fixed by measurement rather than by agreement, the accepted CODATA or IAU value is used.
Worked example
These are the values the Parts Per Million Converter loads by default, and the result it produces from them. Here is the calculation as it stands the moment the page loads.
| Value | 100 |
|---|---|
| From | Parts per million (ppm) |
| To | Parts per billion (ppb) |
| Result | 100000 ppb |
|---|---|
| How it was calculated | 1 ppm = 1000 ppb, so 100 × 1000 = 100000 ppb |
| Reverse conversion | 0.1 ppm (if you meant 100 ppb) |
Parts per million and billion
1 ppm equals exactly 1,000 ppb (parts per billion): a further factor-of-1,000 step below ppm, used when concentrations are smaller still, such as trace contaminant screening in water, air or food safety testing.
Worth knowing
- Environmental and health regulations frequently set maximum contaminant levels in ppb specifically because the substances of concern (certain heavy metals, pesticide residues, some industrial chemicals) are regulated at concentrations too small to sensibly express even in ppm.
- As with ppm, ppb in a water-based (aqueous) solution corresponds closely to micrograms per litre (µg/L), following the same density-based approximation that makes ppm roughly equal to mg/L for dilute aqueous solutions.
- Because ppm and ppb are simple ratios rather than physical units tied to a specific substance, the same conversion factor works regardless of what’s being measured: the numbers translate directly, though interpreting what a given ppm level actually means for safety still depends entirely on the specific substance involved.
Definitions: BIPM SI Brochure · NIST reference on units
How to use it
- Fill in Value.
- Pick a value for From: the options are Parts per million (ppm), Parts per billion (ppb), Parts per trillion (ppt), Percent (%), Per mille (‰) or Milligram per litre (in water) (mg/L).
- Pick a value for To: the options are Parts per million (ppm), Parts per billion (ppb), Parts per trillion (ppt), Percent (%), Per mille (‰) or Milligram per litre (in water) (mg/L).
- Watch the results panel as you type: it recalculates on every keystroke.
- The panel reports Result, How it was calculated and Reverse conversion.
- Copy Link is the quickest way to send the exact scenario to someone else.
What this tool does not do
- Repeated conversions compound rounding, so convert once from the original value where you can.
- Conversion factors use SI definitions; some industries use their own rounded factors.
- Nothing is saved between visits, so keep your own record of anything you need again.
- Confirm the units before you act on the output. The arithmetic is only as sound as what went in.
Frequently asked questions
You need Value, From and To. Nothing starts empty, which means a single edit is enough to get a meaningful answer.
With the values loaded when the page opens, result comes out as 100000 ppb. Any edit re-runs the calculation, so there is no stale number on screen.
No: there is no server involved. Close the tab and the values are gone.
Nothing at all. There is no registration, no paywall and no per-use quota.
The conversion is exact for the method described above. Where a value is rounded for display, the underlying figure keeps full precision.