“On” and “upon” are synonyms. However, “upon” is considered very formal and not that commonly used in conversational English.
|Common idiomatic expressions|
|“On” + specific time||“Upon” + event|
|Emphasise a large amount|
1. “Upon” is very formal compared to “on.”
Although interchangeable, “upon” is often too formal for conversational English—”on” is more common and acceptable.
Compare the following:
- “I left the books on the table.”
- “I left the books upon the table.”
Although both sentences are the same, using “upon” sounds quite old-fashioned and less natural.
a. Very formal and legal language.
- “The title was bestowed upon him by the Queen in 1998.”
- “The proceedings were served upon the defendant last week.”
b. Literary use or period literature, movies and tv shows.
- “I sincerely believe we were put upon this planet for this very purpose.”
- “He put his bowler hat upon his shiny, bald head and briskly walked away without so much as a farewell.”
2. There are some common idiomatic expressions with “upon.”
Using “on” is possible, but less common.
“Once upon a time”
– (expression) used at the beginning of children’s stories to mean “a long time ago.”
This cannot be used with “on.”
- “Once upon a time, there lived a beautiful maiden.”
Not – “Once on a time, there lived a beautiful maiden.”
“Chance upon/on (someone/something)”
– (idiom) to find something or meet someone by accident.
“On” can be used, but this is less common.
- “We chanced upon a fossil while taking a stroll on the beach.”
- “I chanced upon an old friend at the supermarket yesterday. We hadn’t seen other in years.”
“Take (something) upon/on (onself)”
– (idiom) to accept responsibility for doing something without being asked.
“On” can be used, but this is less common.
- “Thanks for taking it upon yourself to organise the event.”
- “She’s taken it upon herself to care for him but I’m not sure if that’s such a good thing.”
“Be upon (somebody)“
– (formal expression) something will happen very soon.
“On” cannot be used.
- “It won’t be long before winter is upon us again.”
Not – “It won’t be long before winter is on us again.”
“Be put upon”
– (informal phrasal verb) to be treated badly by someone who takes advantage of your desire to be helpful.
To me, this is not very common.
- “I don’t mind but I can’t help being put upon.”
Not – “I don’t mind but I can’t help being put on.”
Similar expression: “Put on”
“Put on” has a number of different meanings but requires difference sentence structures, which is why the previous example does not work.
“Put on someone”
– (informal phrasal verb) to tease or playfully deceive someone.
- “I don’t mind but I can’t help like he’s putting me on.”
– (informal noun) an attempt to deceive someone into believing something that is not true.
- “I don’t mind but I can’t help feeling like it’s a put-on.”
3. “Upon” can mean “immediate/soon after.”
This is sometimes interchangeable with “on.”
- “Visitors will be tested upon arrival.”
- “Visitors will be tested on arrival.”
- “Upon his return, he realised he lost his wallet.”
- “On his return, he realised he lost his wallet.”
+ Gerund phrase – using “on” can sometimes sound weird.
- “We congratulated Wally upon hearing the good news.”
- “We congratulated Wally on hearing the good news.”
These sound okay to me.
- “Wally’s son moved out upon leaving school.”
Not – “Wally’s son moved out on leaving school.”
- “Upon watching the documentary, we decided to change our diets.”
Not – “On watching the documentary, we decided to change our diets.”
a. “On” can be used to show when something happens, so this refers to a specific time.
- “We visited my grandmother on Friday.”
Not – “We visited my grandmother upon Friday.”
4. “Upon” can be used to emphasise a large number or amount of something.
“Upon” is placed between two of the same nouns. This can sound more literary and poetic.
- “All I saw were thousands upon thousands of bright pink flowers.”
Not – “All I saw were thousands on thousands of bright pink flowers.”
- “He waited for her year upon year, but never heard from her.”
Not – “He waited for her year on year, but never heard from her.”
* Please note: “year-on-year” is a finance term to compare the financial results in the previous year.
Original posts: 19 April 2021