Formal vs Informal Writing: How to Choose the Right Tone for Every Situation

Not sure if your email to a professor sounds too casual, or if your blog post feels too stiff? The way you write shapes how readers perceive your credibility and personality.

This guide breaks down the key differences between formal and informal writing and shows you how to switch between them with confidence.

What is Formal Writing?

Formal writing serves as the backbone of professional, academic, and official communication. Think of it as wearing a well-tailored suit, it projects authority, competence, and respect for your audience. This style dominates academic papers, business proposals, legal documents, and research studies, maintaining an objective tone with complex sentence structures while avoiding casual language like slang or colloquialisms.

Consider this example: "The research demonstrates a significant correlation between study habits and academic performance." 

Notice the precise vocabulary, third-person perspective, and complete absence of conversational elements. Formal writing builds trust through consistency and professionalism, creating expectations for expertise and thorough analysis rather than personal opinions.

<ProTip title="💡 Pro Tip:" description="Identify your audience first. Formal tone builds credibility for professors or employers, while informal tone helps you connect with peers or blog readers." />

What Is Informal Writing?

Informal writing sounds like a conversation with a friend easygoing, direct, and personable. You’ll see it in friendly emails, blog posts, social media updates, and narrative essays. Common markers include:

<BulletList items="Contractions and everyday vocabulary.|First‑person or second‑person pronouns (I, we, you).|Shorter sentences, emojis, or playful punctuation when appropriate." />

Example sentence: “Research shows that better study habits really do help students do better in school.”

Same idea as the formal example, but lighter and more approachable—perfect when you want to connect rather than impress.

<ProTip title="💡 Pro Tip:" description="Read formal text aloud to catch casual phrases that slip in. If a sentence sounds like everyday conversation, switch to more precise objective wording." />

Key Differences

Understanding how formal and informal writing differ across multiple dimensions helps you make better style choices. Pay attention to these elements when revising your work or switching between audiences, they're the building blocks that create distinct reading experiences.

Tone and Purpose

Formal writing carries a professional, respectful tone designed to inform, analyze, or persuade through logic and evidence. Think of academic journals or policy reports, they maintain emotional distance to project objectivity.

Informal writing, however, embraces a personal and expressive tone. Its primary goals include entertaining, connecting, or sharing experiences. The warmth in informal writing makes complex topics more accessible and memorable.

Matching tone to context isn't just helpful, it's essential for clarity and credibility. A mismatch can confuse readers or undermine your message entirely.

Vocabulary and Word Choice

Formal writing selects precise, discipline-specific vocabulary that demonstrates expertise. Medical papers use terms like "cardiovascular dysfunction" rather than "heart problems." Legal documents choose "terminate" over "end."

Informal writing prefers everyday language that most people understand immediately. It welcomes idioms ("piece of cake"), casual expressions ("totally worth it"), and even regional slang when appropriate.

<ProTip title="💡 Pro Tip:" description="Formal writing avoids exaggerated or emotional language. Instead of amazing breakthrough, try significant advancement." />

Sentence Structure and Grammar

Formal writing constructs longer, more complex sentences that can hold multiple ideas and relationships. These sentences often include subordinate clauses, formal transitions, and varied structure to create sophisticated flow.

Informal writing favors shorter, punchier sentences that mirror natural speech patterns. "It works. Here's why." This directness helps readers process information quickly and maintains engagement.

Grammar rules become more flexible in informal writing, though clarity should never suffer. 

Use of Pronouns

Formal writing typically avoids first and second person pronouns (I, you) in favor of third person or passive voice constructions. "The study indicates" rather than "I found" or "You'll discover."

Informal writing embraces personal pronouns to create connection. Compare these approaches:

The informal version feels more engaging and actionable, while the formal version maintains professional distance.

<BulletList items="Formal: (One might consider the implications of this research).|Informal: (You should definitely think about what this research means)." />

Contractions, Slang, and Idioms

Formal writing spells out contractions completely (do not, cannot, will not) and avoids figurative language that might confuse international readers or create ambiguity.

Informal writing welcomes contractions and colorful expressions. "Don't put all your eggs in one basket" works perfectly in a casual business blog but would seem out of place in a financial report.

Remember that casual expressions can harm clarity or credibility in professional contexts, so choose carefully based on your audience's expectations.

Punctuation and Formatting

Formal writing uses minimal punctuation and follows traditional formatting conventions. Semicolons, em dashes, and complex citation styles appear regularly.

Informal writing might include multiple exclamation points, creative formatting, or even strategic emoji use to enhance meaning and emotional connection.

When to Use Formal Writing

Use a formal tone any time accuracy and authority outweigh friendliness:

<BulletList items="Academic work: essays, theses, peer‑reviewed articles.|Professional documents: grant proposals, annual reports, cover letters.|Legal, medical, and government texts: where wording carries liability." />

Casual: “We’ll look into this soon.”
Formal: “The committee will review the proposal and deliver its findings by 15 September 2025.”

Why it matters: More than three‑quarters of employers say they look for evidence of strong written communication on new‑grad résumés, according to the National Association of Colleges and Employers’ Job Outlook 2025 survey.

<ProTip title="💡 Pro Tip:" description="AI tools can help refine formality quickly without multiple revisions or outside feedback, making the editing process more efficient." />

How to Choose the Right Style

Selecting between formal and informal writing depends on three crucial factors: your audience's expectations, your communication goals, and any existing style requirements. This decision-making framework works whether you're a student switching between assignments or a professional managing multiple writing projects daily.

Know Your Audience – Quick Checklist

✔ Do they expect authority? (professors, executives, officials) → lean formal
✔ Are they peers, customers, or a general crowd? → a conversational tone often lands better
✔ Is English their second language? → keep sentences clear and avoid heavy jargon, no matter the formality

When in doubt, scan similar high‑performing pieces in your field; they reveal what readers already trust.

Know Your Goal – 3‑Step Decision Guide

1. Inform or report findings?
   Use formal tone to project neutrality and credibility.
   
   

2. Persuade or sell?
   Blend formal reasoning with approachable language – clarity first, polish second.
   
   

3. Entertain or build rapport?
   Go informal: contractions, “you,” short lines, maybe a dash of humor.

Rule of thumb: the higher the stakes or legal exposure, the more formality you need.

Follow the Rules – When Style Guides Trump Preference

Some arenas remove guesswork entirely:

<BulletList items="Universities: APA, MLA, Chicago – no freelancing.|Companies: brand voice manuals dictate tone (often semi‑formal).|Public‑facing docs: government notices or legal memos default to strict formality." />

If guidelines are vague, err on the formal side; it’s easier to add warmth later than to backtrack from casual wording that feels unprofessional.

Find the Tone That Fits

Knowing when to choose formal or informal style takes the guesswork out of writing and helps every sentence land the way you intend.

<CTA title="✅ Write With the Right Voice" description="Jenni helps you choose and maintain the best tone for essays emails or reports in one workspace." buttonLabel="Try Jenni Free" link="https://app.jenni.ai/register" />

If you want a tool that matches that helps you find your tone, Jenni can adapt to the formality you select, so you stay focused on clarity instead of formatting.