Difference Between By and Until

Prepositions are words that used before a noun. They are used to show direction, time, place or to introduce an object. “By” and “Until” are two prepositions of time that are confused in sentences.

“By” and “Until” are words used so in English and it is important to know the difference between them.

However, “By” is a preposition that functions as a period in a sentence. By indicates a time limit for something to be done or completed.

By vs Until

Comparison Chart

Parameters of ComparisonByUntil
MeaningDenotes a deadline or endpointDenotes a continuation up to a certain point
TimeframeSpecific point in timeRange of time
CompletionAction must be completed at or before the specified timeAction can be completed any time within the timeframe, but not necessarily at the endpoint
EmphasisStrict deadlineFlexibility
FormalityCan be used in both formal and informal contextsGenerally more formal
ExamplesBy Friday, I need the report finished.”“The store is open until 7 pm.”
ConsequenceMay imply a consequence if not met (e.g., penalty)No inherent consequence

Use Of “By”

“By” refers to the time used to set a time limit for anything that must be completed. This means that the event must end before the deadline. It is used to  highlight a specific moment or moment in the future when that action should be taken or something achieved.

By as a Preposition

Definition and Usage

As a preposition, “by” denotes proximity, indicating a location, time, or method. In terms of location, it signifies nearness or passing a particular point. For instance, “The store is by the park.” When used to express time, it indicates a deadline or a point in the future. “I’ll finish the project by Friday.” “by” can convey a method or means of accomplishing something, as in “By using this tool, you can simplify the process.”

Proximity and Location

“By” is frequently employed to describe the proximity of one object or location in relation to another. This usage is valuable when providing directions, describing spatial relationships, or indicating the location of an event.

Time and Deadlines

In the temporal context, “by” specifies a deadline or the latest acceptable time for an action to be completed. This is crucial in setting expectations and time constraints. For instance, “Please submit your report by the end of the week.”

By as an Adverb

Definition and Usage

As an adverb, “by” can modify verbs, adjectives, or other adverbs. In this context, it conveys the idea of past, indicating a certain period or point in time. For example, “I will be back by 3 PM.”

Past Time Indication

When used as an adverb, “by” emphasizes the completion of an action before a specific time. This is particularly useful for scheduling and planning, ensuring clarity about when an event or task is expected to conclude.

Idiomatic Expressions with By

By and Large

The phrase “by and large” is an idiomatic expression that means or overall. For example, “By and large, the team performed well throughout the season.”

By the Way

Another common idiomatic expression is “by the way,” used to introduce a related topic or a side note. For instance, “I enjoyed the movie. By the way, have you seen the latest episode of the TV series?”

When to use By

Examples of By

  1. Deadline Example: The project should be completed by Friday.
  2. Age Requirement: Applicants must be hired by the age of 30.
  3. Payment Term: The invoice needs to be settled by the end of the month.
  4. Training Completion: Employees must finish the training program by the specified date.
  5. Report Submission: All reports are due by the close of business today.

Use Of “Until”

“Until” is used to describe the state and situation of a period of time at a particular moment. Until and till are standard, but what might surprise you is that “till” is an older word. But the word “till” is used informally instead of to.

Temporal Use

One primary application of “until” is in expressing time-related conditions. When used temporally, “until” specifies the period during which an action or state persists. For instance, “I will wait until 5 PM” conveys the idea of waiting until the clock strikes 5 PM before taking further action.

Conditional Use

“Until” is also employed in expressing conditions that must be met before a change or outcome occurs. Consider the sentence, “She will not leave until she finishes her work.” In this context, the departure is contingent upon the completion of the work.


One crucial aspect to note is the exclusivity of “until.” It implies that the action or condition ceases at the specified point, creating a sense of finality. For example, “The store is open until midnight” suggests that the store closes precisely at midnight.

When to use Until

Examples of Until

  1. Continuous Improvement: Work on the task until it meets the quality standards.
  2. Project Duration: Continue working until the project is successfully delivered.
  3. Training Duration: Trainees should practice until they demonstrate proficiency.
  4. Problem Resolution: Work on the issue until a satisfactory solution is achieved.
  5. Support Availability: The support hotline is available until 5:00 PM.

Difference Between By and Until

  • Meaning:
    • By: Indicates a deadline or a point in time on or before which something should be completed or achieved.
    • Until: Denotes the continuation of a situation or action up to a specified time or event.
  • Temporal Scope:
    • By: Implies completion or accomplishment at any time up to the specified deadline.
    • Until: Specifies a continuous duration leading up to a particular point in time or event.
  • Usage in Time Expressions:
    • By: Used with specific deadlines or times, emphasizing completion.
      • Example: “Submit the report by Friday.”
    • Until: Applied to describe actions or situations leading up to a certain point in time.
      • Example: “Work on the project until 5 p.m.”
  • Inclusive/Exclusive Nature:
    • By: Inclusive, as the task can be completed at any time up to the deadline.
    • Until: Exclusive, indicating activity continues up to but does not include the specified point in time.
  • Contextual Flexibility:
    • By: More versatile, used in a variety of contexts, including deadlines, goals, and achievements.
    • Until: Primarily used in the context of time and continuous action leading up to an endpoint.
  • Examples:
    • By:
      • “Finish your homework by 8 p.m.”
      • “I will complete the project by the end of the month.”
    • Until:
      • “Keep working until I give further instructions.”
      • “The store is open until 9 p.m.”
  • Prepositions:
    • By: Often used independently without needing another preposition.
    • Until: May require pairing with other prepositions, such as “up to,” to convey the intended meaning.
  • Negotiable vs. Non-negotiable:
    • By: Deadlines are negotiable or extendable.
    • Until: Implies a more fixed or non-negotiable endpoint.
  • Temporal Relationship:
    • By: Indicates a point of completion within a flexible time frame.
    • Until: Focuses on the continuous duration leading up to a specific point.


  1. https://academic.oup.com/jos/article-abstract/13/3/221/1673793
  2. https://link.springer.com/article/10.1007/s11673-012-9369-8