The English prepositions in , on , and at are some of the most common words in our language, but they can easily get mixed up. Confusion can arise because not only are they all prepositions of place, but they’re also all prepositions of time; being prepositions of both time and place can make these two-letter words difficult to use. In this guide, we explain how to use in , on , and at . We discuss the rules for each as prepositions of both time and place and share some examples of in , on , and at sentences. Let’s start with reviewing how English prepositions work in general. Your writing, at its best Grammarly helps you communicate confidently Write with Grammarly English prepositions: in , on , and at In English, prepositions are a type of word class that shows relationships between other words in a sentence. Prepositions can describe when something happened (“ in the morning”) or where something happened (“ at the office”), as well as explain connections (“mother of three puppies”) or give extra details (“a movie with subtitles”). Prepositions are always followed by a noun . This noun acts as the object of a preposition because it is what the preposition refers to. Combining the preposition and the object of the preposition creates a prepositional phrase , which also includes any adjectives or determiners the noun uses. For example, the prepositional phrase “behind the tall tree” includes the preposition behind , the object of the preposition tree , the article the , and the adjective tall . There are four types of prepositions: prepositions of time prepositions of place prepositions of direction prepositions of space What makes in , on , and at challenging is that they are prepositions of both time and place. That means each one has at least two different meanings, and all of those meanings can easily get mixed up. To make things more difficult, in , on , and at are not interchangeable —you have to learn all the usages for each to avoid confusing them. English preposition: in In : preposition of time As a preposition of time, in is used with the following words and concepts: instant and moment seconds, minutes, and hours amounts of days groups of years (decades, centuries, etc.) the past, present, and future times of day: morning, afternoon, evening night (specific time) In : preposition of time examples in a few moments in a couple of minutes in less than a decade in the middle of the night In : preposition of place As a preposition of place, in is used with the following words and elements: general locations locations within large places like cities, countries, and continents the sky and atmosphere In: preposition of place examples in the dining room in my third class in the blue sky in the farthest reaches of space English preposition: on On : preposition of time As a preposition of time, on is used with the following words and concepts: days of the week times of day used with days of the week yearly events like birthdays and holidays weekend (American English) On : preposition of time examples on Saturday evening on our anniversary on Lunar New Year on January 19 (on the 19th of January) On : preposition of place

As a preposition of place, on is used for the following words and ideas: things on the surface of something else (tables, walls, etc.) locations near a body of water floors of a building On: preposition of place examples on the Amazon River on the fifth floor English preposition: at At : preposition of time As a preposition of time, at is used for: times of day: dawn , dusk night (unspecific time) weekend (British English) At : preposition of time examples At : preposition of place As a preposition of place, at is used with these categories: precise locations specific addresses At: preposition of place examples at the dinner table at the homecoming dance at 720 Main Street When not to use in , on , or at Don’t use with next and a time When using next as an adjective before a time, you can omit in , on , or at . The sentence will work without a preposition of time. Let’s go on next Friday. Let’s go next Friday. Don’t use the last and a specific time Similarly, you can also omit in , on , or at when using last as an adjective before a time period, as long as you are talking about a specific time. We stayed home at last night. We stayed home last night. We went on vacation in last June. They went on vacation last June. However, if you’re using last with an unspecified time, you still need a preposition. Typically, if the phrase with last uses an article or other determiner, it is unspecific and should include in , on , or at. on the last day of school at our last team breakfast Keep in mind that the phrase “at last” acts as an adverb , so these rules for prepositions don’t apply to it. Last night, at our last meeting, we picked a group name at last! In , on , and at FAQs What are English prepositions? In English, prepositions are a type of word class that shows relationships between other words in a sentence. Prepositions can describe when something happened (“ in the morning”) or where something happened (“ at the office”), as well as explain connections (“mother of three puppies”) or give extra details (“a movie with subtitles”). What type of prepositions are in , on , and at ? The words in , on , and at are prepositions of both time and place. That means each one has at least two different meanings, and all of those meanings can easily get mixed up. Can in , on , and at be used interchangeably? The prepositions in , on , and at are not interchangeable. Each has its own rules and suggested usages. However, sometimes the same words or sentence can use different prepositions, although the meaning will change slightly. Parts of Speech What Are Verbs With “S”? Parts of Speech Collective Nouns: How Groups Are Named in English Parts of Speech What Part of Speech Is “Is”? Parts of Speech What Part of Speech Is “Into”? Parts of Speech What Part of Speech Is “By”? Parts of Speech How to Use Indefinite Pronouns