Difference Wiki

Mostly vs. Mainly: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Published on November 20, 2023
Mostly means largely, for the most part. Mainly means primarily, chiefly.

Key Differences

Mostly is often used to indicate that something is true or applies to the majority of situations, people, or things, but not all. Mainly, on the other hand, suggests that one particular thing is primarily responsible or significant among others. They both imply a degree of exclusivity, but mostly leans towards quantifiable aspects while mainly hints at qualitative importance.
In usage, mostly is apt for instances where there's a notable but not absolute dominance. For example, "The crowd was mostly teenagers." It suggests a large part but not entirety. Mainly tends to underscore the primary cause, reason, or factor, as in, "The event was mainly for charity." It emphasizes the chief purpose or element.
When we talk about proportion, mostly is your word. It fits well when you're quantifying: "The class is mostly international students." Here, it implies a high percentage. Conversely, mainly is best for emphasizing the principal element: "The discussion was mainly about politics," where politics is the core subject.
Mostly also has a flavor of generalization, suitable for broad strokes: "She's mostly quiet in meetings." It doesn’t exclude exceptions. Mainly leans towards specificity, highlighting the primary aspect: "He’s mainly interested in jazz," focusing on jazz as the key interest.
In some contexts, both words can be interchangeable without much change in meaning. For instance, "The participants were mostly/mainly women." However, the nuance remains, with mostly indicating a high number and mainly underscoring women as the primary group.

Comparison Chart

Emphasis Type

Quantitative dominance
Primary focus or cause

Context Usage

Generalization, majority instances
Specificity, chief aspects


High proportion, not absolute
Main cause or reason

Example Scenario

Population, characteristics
Interest, purpose


Suggests exceptions are possible
Indicates prime importance

Mostly and Mainly Definitions


For the greater part.
The book is mostly fiction.


He is mainly interested in art.


The attendees were mostly students.


The meeting is mainly to discuss budgets.


She is mostly on time for meetings.


The seminar is mainly for beginners.


In most cases.
The weather here is mostly sunny.


The fund is mainly for research purposes.


His success is mostly due to hard work.


Predominantly in focus.
The story is mainly about friendship.


For the greatest part; mainly.


For the most part; chiefly.


Generally; usually.


When should I use mostly?

Use mostly when referring to the greater part of something or when quantifying.

Does mainly imply exclusivity?

Mainly suggests a primary focus or cause, but not necessarily exclusivity.

Is mainly used to highlight the main reason?

Yes, mainly is used to emphasize the primary reason or cause.

Is mainly good for emphasizing the key aspect?

Yes, mainly is used to underscore the chief or primary aspect.

Does mostly suggest a majority?

Yes, mostly implies that something applies to the majority.

Does mainly convey a sense of importance?

Yes, mainly conveys the importance or primacy of something.

Can mostly be used to describe common occurrences?

Yes, mostly is suitable for describing what commonly or usually happens.

Is mainly appropriate for emphasizing the main cause?

Yes, mainly is appropriate for emphasizing the main cause or reason.

Can mainly and mostly be used interchangeably?

Sometimes, but mainly emphasizes the primary element while mostly implies a large proportion.

Is mostly used for quantities?

Yes, mostly is often used to indicate a large amount or proportion.

Can mostly be used for generalizations?

Yes, mostly is suitable for making general statements.

Can mainly be used to specify the primary interest?

Yes, mainly is appropriate for specifying the main interest or focus.

Does mainly focus on qualitative aspects?

Yes, mainly often focuses on qualitative aspects like reasons or purposes.

Can mostly be used to describe usual tendencies?

Yes, mostly can be used to describe what usually or typically happens.

Can mostly indicate exceptions?

Yes, mostly suggests that there might be exceptions to the general trend.

Does mostly imply not always?

Yes, mostly implies that there are instances where it might not apply.

Can mainly indicate the primary purpose?

Yes, mainly can indicate the primary purpose or intention.

Is mostly good for statistical references?

Yes, mostly is often used in statistical contexts to indicate a large part.

Is mostly appropriate for indicating a high percentage?

Yes, mostly is often used to indicate a high percentage or proportion.

Is mainly used for pinpointing the chief subject?

Yes, mainly is used to point out the chief or primary subject.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

Trending Comparisons

Popular Comparisons

New Comparisons