# Need useful ways to express "parts per million" **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [March 3, 2018, 6:15am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955 "2018-03-03T06:15:52Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\ **Post date:** [March 3, 2018, 6:15am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/1 "2018-03-03T06:15:52Z")
What useful visual ways or analogies are there to convoy “parts per million?” Like, a cup of Kool Aid poured into a family swimming pool? (Are there 1 million cups of water in that sort of pool?) A big mansion-full of purple gas released in the Superdome stadium? Etc. Etc. ---
**Author:** ![snfaulkner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snfaulkner/32/433_2.png) [@snfaulkner](https://boards.straightdope.com/u/snfaulkner)\ **Post date:** [March 3, 2018, 6:22am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/2 "2018-03-03T06:22:36Z")
Dollars? What can you buy with $1 vs $1 million… ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [March 3, 2018, 6:38am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/3 "2018-03-03T06:38:38Z")
An Olympic size pool measures: 50 meters long, 25 meters wide, and a minimum of 2 meters deep. This converts to 660,430.1339 U.S. gallons. At 16 cups per gallon, we’re talking 10,566,880 cups. Your cup runneth over. ---
**Author:** ![penultima\_thule](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/penultima_thule/32/3833_2.png) [@penultima\_thule](https://boards.straightdope.com/u/penultima_thule)\ **Post date:** [March 3, 2018, 7:06am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/4 "2018-03-03T07:06:14Z")
1 drop = 0.05ml 20 drops = 1 ml 20,000 drops = 1 litre 75,700 drops = 1 US gallon 302,800 drops = 1 x 4US gallon bucket 1,000,000 drops = 3.3 buckets = 13.2 US Gallons A US keg of beer is 15.5 gallons so 1ppm is approx 1.2 of drops of beer per keg or a drop in 3.3 buckets. ---
**Author:** ![PatrickLondon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/patricklondon/32/4422_2.png) [@PatrickLondon](https://boards.straightdope.com/u/PatrickLondon)\ **Post date:** [March 3, 2018, 7:25am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/5 "2018-03-03T07:25:01Z")
How precise do you want to be? There’s always the old phrase “a drop in the ocean”. ---
**Author:** ![Alley\_Dweller](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alley_dweller/32/430_2.png) [@Alley\_Dweller](https://boards.straightdope.com/u/Alley_Dweller)\ **Post date:** [March 3, 2018, 8:15am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/6 "2018-03-03T08:15:19Z")
One person in San Jose CA (pop 1,025,350) or one person in Austin TX (pop 947,890). Not exactly one million, but pretty close. [Source.](https://factfinder.census.gov/faces/tableservices/jsf/pages/productview.xhtml?src=bkmk) > [@Velocity](#): > > What useful visual ways or analogies are there to convoy “parts per million?” Use a [convoy](https://imagesvc.timeincapp.com/v3/mm/image?url=https%3A%2F%2Ftimedotcom.files.wordpress.com%2F2014%2F08%2Frussia-aid-convoy.jpg&w=800&q=85)! ---
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [March 3, 2018, 8:58am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/7 "2018-03-03T08:58:44Z")
> [@Duckster](#): > > An Olympic size pool measures: 50 meters long, 25 meters wide, and a minimum of 2 meters deep. > > This converts to 660,430.1339 U.S. gallons. At 16 cups per gallon, we’re talking 10,566,880 cups. > > Your cup runneth over. far easier with metric and more understandable across the world 50 x 25 x 2 = 2500 cubic metres of water A cubic metre contains (100 x 100 x 100) 1 million cc of water or 1000 litres so a half litre bottle of coke tipped into an olympic-sized swimming pool is the equivalent of 1 part in (1000/0.5 x 2500) 5 million and a larger 2 litre bottle gets you close to 1 ppm ---
**Author:** ![don\_t\_ask](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@don\_t\_ask](https://boards.straightdope.com/u/don_t_ask)\ **Post date:** [March 3, 2018, 9:14am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/8 "2018-03-03T09:14:45Z")
I generally describe it as 3 drops in a bathtub full of water. ---
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [March 4, 2018, 4:57am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/9 "2018-03-04T04:57:26Z")
One million days covers most of recorded history (2740 years). Dennis ---
**Author:** ![burpo\_the\_wonder\_mutt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/burpo_the_wonder_mutt/32/365_2.png) [@burpo\_the\_wonder\_mutt](https://boards.straightdope.com/u/burpo_the_wonder_mutt)\ **Post date:** [March 4, 2018, 5:23am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/10 "2018-03-04T05:23:16Z")
> [@Alley\_Dweller](#): > > One person in San Jose CA (pop 1,025,350) or one person in Austin TX (pop 947,890). Not exactly one million, but pretty close. [Source.](https://factfinder.census.gov/faces/tableservices/jsf/pages/productview.xhtml?src=bkmk) > > Use a [convoy](https://imagesvc.timeincapp.com/v3/mm/image?url=https%3A%2F%2Ftimedotcom.files.wordpress.com%2F2014%2F08%2Frussia-aid-convoy.jpg&w=800&q=85)! Wait a minute, that was just a _thousand_ screamin’ trucks (an’ eleven long-haired Friends o’ Jesus in a chartreuse micra-bus, 10-4.) ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [March 4, 2018, 8:14am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/11 "2018-03-04T08:14:45Z")
As an engineer, I’m fairly literal-minded, so: 1 ppm = 1 mg/kg i.e. one part per million equals 1 milligram per kilogram ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 4, 2018, 2:31pm UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/12 "2018-03-04T14:31:12Z")
> [@robby](#): > > As an engineer, I’m fairly literal-minded, so: > > 1 ppm = 1 mg/kg > > i.e. one part per million equals 1 milligram per kilogram Or 1 gram / metric ton, which I think is easier to visualize. That would be 1 ml per ton of water. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 4, 2018, 2:37pm UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/13 "2018-03-04T14:37:10Z")
> [@PatrickLondon](#): > > How precise do you want to be? There’s always the old phrase “a drop in the ocean”. One drop in the entire Atlantic Ocean would be about 1 part in 10 quadrillion. That’s ten trillion times smaller than 1 ppm. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 4, 2018, 6:47pm UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/14 "2018-03-04T18:47:22Z")
> [@robby](#): > > As an engineer, I’m fairly literal-minded, so: > > 1 ppm = 1 mg/kg > > i.e. one part per million equals 1 milligram per kilogram I appreciate your literal-minded engineerness, but for most people, this is not any more useful than the original 1 PPM description. The goal is to express this quantity using everyday items that non-engineers find familiar and can relate to. For example, most folks are familiar with a gallon, and most folks are familiar with an inch. So take a cube of water 1/16 of an inch on a side: that’s about one millionth of a gallon. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [March 4, 2018, 7:58pm UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/15 "2018-03-04T19:58:53Z")
This here is a nice demonstration of ink in water (about how to picture why CO2 concentrations in the atmosphere are significant) to show that something being at parts per million in a solution is something that can have a big impact. [QUOTE] Dan Miller Published on Mar 7, 2010 I use ink to demonstrate how CO2 can have a big impact on warming the earth even though it is a very small percent of the atmosphere. [/QUOTE] ---
**Author:** ![minor7flat5](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/minor7flat5/32/258_2.png) [@minor7flat5](https://boards.straightdope.com/u/minor7flat5)\ **Post date:** [March 4, 2018, 8:19pm UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/16 "2018-03-04T20:19:06Z")
> [@Velocity](#): > > …Like, a cup of Kool Aid poured into a family swimming pool? (Are there 1 million cups of water in that sort of pool?)… You are very close. My own average-sized pool holds 18,500 gallons of water (all pool owners know their size because of the need to calculate chemical adds). 18,500 gal / 1,000,000 = 0.0185 gal 0.0185 gal \* 128 oz/gal is about 2.4 oz. So it’s about the size of one of those tiny Dixie cups you find in bathrooms. ---
**Author:** ![Enginerd](https://avatars.discourse-cdn.com/v4/letter/e/bcef8e/32.png) [@Enginerd](https://boards.straightdope.com/u/Enginerd)\ **Post date:** [March 4, 2018, 11:00pm UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/17 "2018-03-04T23:00:04Z")
If you’re okay being a bit crass about it, [this page](http://oasisdesign.net/water/quality/coliform.htm) translates fecal coliform counts into the more intuitive units “buttwipes per swimming pool” (or per bathtub, or per bottle :eek:, depending on the counts). Gives quantitative derivations and everything. ---
**Author:** ![Baal\_Houtham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/baal_houtham/32/13604_2.png) [@Baal\_Houtham](https://boards.straightdope.com/u/Baal_Houtham)\ **Post date:** [March 5, 2018, 1:04am UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/18 "2018-03-05T01:04:36Z")
Once when I was trying to illustrate the generations of man (related to evolution) I decided that a screen door demonstrated it pretty well — with each square representing a generation of 20 years. I forget the details now. BUT, standard screening has an 18x16 mesh for 288 squares per square inch. A rectangle of screening 48” x 73” will put you around 1,009,000. You can carry it under your arm. ---
**Author:** ![Shoeless](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/shoeless/32/7099_2.png) [@Shoeless](https://boards.straightdope.com/u/Shoeless)\ **Post date:** [March 5, 2018, 3:58pm UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/19 "2018-03-05T15:58:28Z")
> [@Alley\_Dweller](#): > > One person in San Jose CA (pop 1,025,350) or one person in Austin TX (pop 947,890). Not exactly one million, but pretty close. [Source.](https://factfinder.census.gov/faces/tableservices/jsf/pages/productview.xhtml?src=bkmk) Or as the old joke goes, there are a billion people in China. So even if you are a one-in-a-million kind of guy, there are still 1,000 other people just like you. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [March 5, 2018, 5:12pm UTC](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955/20 "2018-03-05T17:12:59Z")
I think many of us could picture a ten-by-ten arrangement of people standing. And we could with some difficulty imagine a vast field on which there was an arrangement of one hundred by one hundred of these groups. That’s (10\*10)_100_100= one million. So, just one of those people in that whole crowd. [Next page](https://boards.straightdope.com/t/need-useful-ways-to-express-parts-per-million/809955.md?page=2)