1ppm – Have You Ever Wondered What 1ppm Means?

Updated on November 28, 2019
Stive Smyth profile image

Stive has BEng Hons 1st Cl Electronics w/masters level modules from the O.U. and is retired from 45+ years in various fields of electronics.


Why ppm - What Is It? What Does it Mean?

1ppm literally means “one Part-Per-Million(-parts)” and could be described as either “one part-in-a-million(-parts)” or “1 part-in-one-million(-parts)”.

ppm as a standalone symbol without any numerals means parts-per-million (plural)

Many people can grasp what that means – that the liquid or solid in question, be it element, compound, substance, mixture, mineral, or other, contains one ‘foreign’ part for each 999,999 major or base parts of the material. So it is the one part in a million parts or particles.

It could also be used for gases, such as air, but the ‘foreign bodies’ in air usually are specified as ‘per volume of air’ (usually 1m3), not ppm, and are also described by their physical size. The specifications for integrated circuit cleanrooms are good examples of this description.

If the 1ppm is unwanted then the base material is said to be contaminated with an unwanted foreign body or contaminant such as dust or other particle, for example, in a chocolate factory.

If the 1ppm is purposefully added then the base material has been infused or doped, such as the materials used in the manufacture of transistors and integrated circuits.


Why use ppm and not Per Cent (%)?

Cent is a Latin root word meaning 100.

Some examples of its usage are the coinage cent, so-called because there are 100 in a dollar, and similarly centavos with pesos, centimes with francs. Other examples are century which means 100 years and, of course, the Roman Centurion, a commander of one hundred legionaries and support staff.

Earlier variations of per cent include percent (as a single word), per cent. (with a period or full stop, ‘.’), per-cent (hyphenated) and per centum (a legal term), but the modern term is per cent.

Per cent (%) literally means per-one-hundred and could easily have been designated as pph which could stand for parts-per-hundred.

And therein lies the simple relationship between percent (pph) and ppm – that ppm is actually a very much smaller amount and is in fact only 1/10,000th of one percent or 0.0001% and would be too small to envisage and hence required its own designation.


ppm is the common 'symbol' used, albeit initials and not a real symbol such as % (per cent) or ‰ (mille/mil). Although it is a frequently used and reasonably well known symbol, it is not a part of the S.I. system of measurement symbols.

Due to the parameter being quantity-per-quantity it is a ratio and therefore has no units of measurement.

From % to ppm, Visually – For those who understand clearer by “seeing”, rather than the math.

% (pph)
‰ (ppt)
Accepted Name
per cent
mille / mil
Suggested Name to Assist Understanding
parts per hundred
parts per thousand
parts per ten thousand
parts per hundred thousand
parts per million
1% as a Fraction
1/10 %
1/100 %
1/1000 %
1/10,000 %
1% as a Decimal Fraction
1 %
0.1 %
0.01 %
0.001 %
0.0001 %

ppm Specifications

It is possible to easily calculate how many ppm-items there are in an ‘amount’, given the amount and the ppm specification.

It is often easier to explain with examples, as follows...

Take, for example, the crystal clock in your laptop, tablet, pad or smart phone. If it runs at 3.7GHz and is specified at +/-20ppm then the calculation is performed similar to percentage calculations.

If it were +/-20%, then 3.7Ghz+/-20% = 3.7x109 x 20/100 = 740x106 or 740MHz

Similarly with +/-20ppm, 3.7GHz+/-20ppm = 3.7x109 x 20/1000000 = 74x103 or 74kHz

Thus, a 3.7GHz crystal clock with a +/-20ppm specification (spec.) can be allowed to drift +/-74kHz or +/-74,000Hz (Hz means Hertz, which are the single or unit parameters of frequency).

Taking this a step further, we can calculate the upper and lower limits of the drift as follows –

3.7x109 + 74x103 = 3700 x106 + 0.074 x106 = 3700.074x106 for the upper limit

3.7x109 – 74x103 = 3700 x106 – 0.074 x106 = 3699.926x106 for the lower limit


In the world of chocolate, for example, the contaminant ppm specification can be easily quoted as mg/kg, or milligram-per-kilogram, because a milligram is 1/1000th of a gram and a kilogram is 1000 grams and hence the mg is 1ppm of a kg.

The major contaminants in the chocolate and candy world are usually lead and cadmium and the specifications are often quoted as low as 0.1ppm which is exceedingly low.


The liquids’ contaminants specifications can be quoted as mg/L and as 1L weighs 1kg then this is also 1ppm. They are sometimes quoted as fractions of ppm/Litre.


ppm Conversions

It is possible to convert between ppm and % and vice versa.

For example, convert 1ppm to an equivalent percentage value –

1ppm can be written as 1/1000000. And n% can be written as n/100.

Such that 1/1000000 = n/100

Hence 100/1000000 = n.

Hence n = 0.0001

Therefore 1ppm = 0.0001%

And conversely, convert 1% into ppm –

n ppm can be written as n/1000000. And 1% can be written as 1/100.

So that n/1000000 = 1/100

Hence n = 1000000/100

Hence n = 10,000

Therefore 1% = 10,000ppm

Other Conversions

% to Decimal Fractions

Simply divide the given % figure by 100

Hence 25% becomes 25/100 which then further becomes 0.25 as a decimal fraction

% to Fractions

Simply write down the given % figure over 100

Hence 25% becomes 25/100

But now, do not reduce it to a one-line decimal fraction, as above.

Instead, reduce it to the lowest possible simple fraction.

Hence 25/100 is equivalent to ¼ as a simple fraction.

Therefore 25% = ¼

© 2019 Stive Smyth


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, owlcation.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://maven.io/company/pages/privacy

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)