all/most/some (of) + noun

Writers often add of after quantifiers like all, most, and some and end up with heavy or awkward phrases. Most of the time you can drop of and get a cleaner sentence - but there are clear exceptions. Below are quick rules, simple diagnostics, and many practical rewrites for work, school, and casual contexts.

Quick answer

If a quantifier (all, most, some) is followed directly by a noun phrase with no determiner, omit of (Most people, Some fruits, All students). Use of when the quantifier is followed by a pronoun (all of them) or when you need a partitive with a determiner (most of the people in the room).

Correct: Most people know the bus schedule. (not Most of people)
Correct: Some of the cookies were gone. (partitive with determiner)
Correct: All the students passed. (All of the students is also acceptable but heavier.)

Core explanation: the grammar behind of

Of appears after quantifiers in two main situations: when a pronoun follows (all of them) and when a determiner creates a clear partitive (some of the cookies, most of the people in the meeting).

Drop of with a bare plural or uncountable noun: Most people, Some fruit, All students.
Keep of with pronouns: all of them, most of us.
With a determiner (the, my, these), both forms can be grammatical for all; for some and most, of often signals a subset.

Wrong: Most of people enjoy coffee in the morning.
Right: Most people enjoy coffee in the morning.
Wrong: Some of fruits contain vitamin C.
Right: Some fruits contain vitamin C.
Wrong: All of students were present.
Right: All the students were present.

Real usage and tone: how formality and emphasis affect the choice

For concise formal writing prefer shorter forms (Most people, All students). Use of when you want emphasis, to mark a subset, or when a pronoun follows.

Concise: All students submitted the form.
Emphatic/partitive: All of the students who stayed late helped clean up.
Pronoun rule: Use of with pronouns (all of them, some of us).

Work: Most people in marketing have completed the survey. (Concise, professional.)
School: All the students who finished early may leave. (Natural classroom phrasing.)
Casual: Some friends are already at the cafe. (Short and colloquial.)

Examples: realistic wrong/right pairs across contexts

Below are grouped wrong/right pairs. Replace nouns and determiners to match your situation while keeping the quantifier pattern.

Work - Wrong: All of engineers on the project asked for extra time.
Work - Right: All the engineers on the project asked for extra time.
Work - Wrong: Most of employees will attend the training next Friday.
Work - Right: Most employees will attend the training next Friday.
School - Wrong: Some of students failed to include citations.
School - Right: Some students failed to include citations.
School - Wrong: Most of the class understood the experiment.
School - Right: Most of the class understood the experiment. (Natural partitive because of the determiner.)
Casual - Wrong: All of friends are coming tonight?
Casual - Right: Are all your friends coming tonight?
Casual - Wrong: Some of people at the party were dancing.
Casual - Right: Some people at the party were dancing.

Rewrite help: fix your sentence in three quick checks

Run this mini-check: (1) Is a pronoun next? (2) Is there a determiner like the/my/these? (3) Is the noun a bare plural? Use the answers to choose the right form.

If a pronoun follows: keep of - All of them, Most of us.
If a determiner follows and you want concision: you can drop of - All the candidates / All candidates.
If it's a bare plural: drop of - Most people, Some books, All students.

Rewrite:
Original: All of staff must complete the form.
Rewrite: All staff must complete the form.
Rewrite:
Original: Most of the customers liked the update.
Rewrite: Most customers liked the update. (If you mean a defined subset, keep of: Most of the customers in yesterday's trial liked the update.)
Rewrite:
Original: Some of students didn't hand in the homework.
Rewrite: Some students didn't hand in the homework.

Try your own sentence

Test the whole sentence rather than the phrase alone - context usually makes the right choice clear. Paste your sentence into the widget below for a quick check.

Memory tricks and quick diagnostics

Two short rules to remember: "Pronoun? Keep of." and "Bare plural? Drop of." Use the swap test: remove of and read the sentence aloud - if it still sounds natural, drop of.

Swap test: remove of - does it read naturally? If yes, keep the shorter form.
Pronoun rule: all of them / most of us (always keep of with pronouns).
Partitive check: if you name a subset with extra detail, of + determiner adds precision (most of the attendees from New York).

Similar mistakes to watch for

Other quantifiers follow different patterns: both, each, and half behave differently, so check them separately.

Both: Both of the candidates / Both candidates can be correct; both people (bare plural) is fine without of.
Each: Each child arrived early (do not say each of child). Use each of the + plural when followed by a determiner: each of the students.
Half: half of the class (partitive) and half the class (both common).

Wrong: Each of students must submit the form.
Right: Each student must submit the form. Or: Each of the students must submit the form.
Wrong: Both of people agreed to the terms.
Right: Both people agreed to the terms. Or: Both of the people agreed to the terms.

Hyphenation notes (when quantifiers meet modifiers)

Hyphens don't affect the of decision, but they matter for compound adjectives. Fix of usage first, then check hyphens for modifiers.

Compound adjective: an all-time high (hyphen when used before a noun).
Different phrase: He works all the time (no hyphen, different meaning).
After deciding about of, scan for compound-adjective hyphens separately.

Spacing, punctuation and small style checks

After you correct of usage, do a quick pass for commas, agreement, and spacing. Changing phrasing can shift subject-verb agreement or require commas around interrupters.

Check verbs: All the students are vs All the team is (collective vs plural usage varies by variety).
Punctuate interrupters: Most people, however, prefer shorter meetings.
Read the sentence aloud after edits - spacing and agreement errors stand out when spoken.

Usage: Agreement check: Wrong: All of the group were late.
Right: All the group was late. (Or All the group were late, depending on regional preference and whether you treat the group as a unit.)

FAQ

Is "all of the students" incorrect?

No. "All of the students" is not incorrect, but it's slightly heavier than "all the students." Use the shorter form for concision; keep "all of the students" for emphasis or a partitive feel.

When must I use of after most or some?

Keep of when a pronoun follows (most of them) or when you need a partitive with a determiner to name a subset (some of the applicants from London).

Which is better in an academic essay: "Most people" or "Most of the people"?

"Most people" is cleaner for general statements. Use "Most of the people" when you refer to a specific group already defined in the context (Most of the people in the study responded...).

Should I always drop of in work emails?

Prefer shorter forms for readability (Most employees, All participants), but keep of when you mean a specific subset or when a pronoun follows. If in doubt, read the sentence aloud - if the shorter version sounds natural, use it.

How can I quickly check a sentence for this error?

Use the three-step check: (1) Is there a pronoun next? If yes, keep of. (2) Is there a determiner and you mean a specific subset? If yes, consider of. (3) Is it a bare plural? If yes, drop of. If unsure, remove of and read the sentence aloud - if it still reads smoothly, drop it.

Quickly check your sentence

Use the diagnostic rules above, then paste your sentence into a grammar checker to catch edge cases and ensure agreement and punctuation are correct.