# Formal vs Informal Sentences: Examples & How to Fix It

> A sentence is more formal when it avoids contractions, slang, and casual phrasal verbs, and uses precise vocabulary instead. “Kids can’t figure it out” is informal; “Students are unable to understand it” is formal.

**URL:** https://humanit.app/writing/formal-vs-informal  ·  **Updated:** May 2026  ·  Humanit

A sentence is more formal when it avoids contractions, slang, and casual phrasal verbs, and uses precise vocabulary instead. “Kids can’t figure it out” is informal; “Students are unable to understand it” is formal. Paste your own sentence into the free checker below to fix it in one click.

## How it works

1. **Spot the pattern** — Scan for contractions, first-person asides, vague intensifiers (“really”, “a lot”), and conversational phrasal verbs. The more of these, the more informal the sentence reads.
2. **Apply the rule** — Expand contractions, replace phrasal verbs with single formal verbs, and swap casual words for precise ones — without making the sentence stiff or padded.
3. **Check your sentence** — Paste your text into the grammar checker below — it flags the issue and shows the correction.
4. **Re-read it** — Read the corrected version aloud to confirm it says exactly what you meant.

## The rule

Formal writing avoids contractions (“don’t” → “do not”), slang and idioms, and casual phrasal verbs (“find out” → “determine”), while keeping sentences complete and precise.

## How to spot it

Scan for contractions, first-person asides, vague intensifiers (“really”, “a lot”), and conversational phrasal verbs. The more of these, the more informal the sentence reads.

## How to fix it

Expand contractions, replace phrasal verbs with single formal verbs, and swap casual words for precise ones — without making the sentence stiff or padded.

## The most common mistake

Assuming “formal” means “longer”. Formality is about word choice and tone, not length — a formal sentence can still be concise. If you’re not sure whether your sentence has the problem, paste it into the checker above — it catches this and explains the fix in plain language.

**Before → after**

| ❌ Incorrect | ✓ Corrected | Why |
| --- | --- | --- |
| Kids these days don’t get it. | Today’s students often struggle to understand it. | No contraction or slang |
| We need to find out what went wrong. | We must determine what went wrong. | Phrasal verb → formal verb |
| The results were pretty good. | The results were satisfactory. | Vague intensifier → precise word |

## FAQ

**Which sentence is more formal?**

The one without contractions, slang, or casual phrasal verbs. “The committee will not approve the request” is more formal than “They won’t okay it.”

**When should I write formally?**

Academic essays, cover letters, reports, and professional emails generally call for a formal tone. Personal blogs, social posts, and casual messages do not.

**How do I check my own writing for this?**

Paste your text into the free grammar checker on this page. It flags the issue, suggests a correction, and explains why — so you learn the rule, not just the fix.

**Is it free?**

Yes — your first run needs no account, and a free account adds 5 more, each up to 1,500 words. They are a one-time grant, not a daily allowance. Upgrade for a word pool that removes the per-run cap, or use the free iOS app.

## Related pages

- [Parallel Structure](https://humanit.app/writing/parallel-structure) ([markdown](https://humanit.app/writing/parallel-structure.md))
- [Reduce Wordiness](https://humanit.app/writing/reduce-wordiness) ([markdown](https://humanit.app/writing/reduce-wordiness.md))
- [Comma Splices](https://humanit.app/writing/comma-splice) ([markdown](https://humanit.app/writing/comma-splice.md))
- [Run-on Sentences](https://humanit.app/writing/run-on-sentence) ([markdown](https://humanit.app/writing/run-on-sentence.md))
- [AI Humanizer](https://humanit.app/humanize) — Rewrite AI text to read human. ([markdown](https://humanit.app/humanize.md))
- [AI Detector](https://humanit.app/detect) — Check if text reads as AI-written. ([markdown](https://humanit.app/detect.md))

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_Last updated: June 2026._