How to Switch Informal to Formal Writing in 2026

Key takeaways

• Informal to formal writing means expanding contractions, replacing slang and removing filler while keeping the original meaning.
• Mark every informal element in your draft before you edit, so you know the full scope.
• Aim for an average sentence length under 20 words and a Flesch reading ease score between 40 and 60.
• Replace vague claims with specific numbers and named sources, and never invent statistics.
• Have one reader who knows the subject confirm that the formal version says what you meant.

How do you switch informal to formal writing?

Informal to formal writing means rewriting casual, conversational text into precise, professional language without changing the meaning. You swap slang, contractions and vague phrasing for complete sentences and exact terms. Plan about 30 minutes for a one-page draft. The one thing that matters most: keep the tone formal, but keep the claim the same, so the reader still gets your point.

Which informal to formal rules matter before you start?

• The original text you want to rewrite, such as a blog intro, a product page or a cold email
• A style guide or a short list of banned words for your brand
• The audience and channel, since an investor memo and a SaaS help article need different levels of formality
• A word processor with a readability check, such as Microsoft Word's Editor or Grammarly
• A second reader who knows the product, so you can catch meaning changes

Step 1: Identify the informal parts of your draft

Read the text once and mark every informal element. Look for contractions (don't, it's), slang (super, kinda, a ton), first-person filler (I think, honestly), abbreviations (info, pls) and sentence fragments. Highlight each type in a different colour.

This step matters because you cannot fix what you have not labelled. Most informal drafts contain 20 to 40 markers per page. A quick pass shows you the scope before you edit a single sentence, and it tells you whether a light edit or a full rewrite is needed.

Step 2: Replace contractions and slang with full words

Expand every contraction. "Can't" becomes "cannot," and "it's" becomes "it is." Swap slang for neutral vocabulary: "a ton of" becomes "a large number of," and "kinda" becomes "somewhat" or disappears. In Microsoft Word, open Find and Replace and turn on "Match whole word" so you do not break words like "scant."

Keep your changes small at this stage. Your goal is correct word choice, not new sentences. Save a copy before you start, so you can compare the two versions side by side.

Step 3: Rebuild sentences and remove filler

Formal writing favours complete, direct sentences. Break long run-on sentences at conjunctions like "and" or "but" when they join two separate ideas. Delete filler such as "basically," "just," "really" and "you know." Aim for an average sentence length under 20 words.

Then run a readability check. Grammarly and Microsoft Word both show a Flesch reading ease score. For professional audiences, a score between 40 and 60 usually reads as formal without being dense.

Step 4: Replace vague claims with precise language

Informal text often says "a lot of users love it." Formal text says "over 3,000 users rated it 4.6 out of 5 on the Chrome Web Store." If you do not have a number, describe the scope honestly with "several customers reported" rather than "everyone says." Never invent statistics to sound formal.

Name your sources. When you cite research, name the organisation and the date, for example "according to Gartner's latest survey." Named sources build trust with readers who expect evidence, and they make your claim checkable.

Step 5: Check the tone against your channel

Formal does not mean stiff. A cold email to a founder can be formal and still short. A product page can be formal and still address the reader as "you." Read the draft aloud and ask whether a peer would say it in a meeting. If a sentence sounds like a legal notice, simplify it.

For detailed guidance on word choice and tone, the Purdue Online Writing Lab covers formal style in depth, and the guide is free to read.

Step 6: Proofread and get one human review

Run the final text through a spelling and grammar check, then read it once more on paper or on a second screen. Confirm that every number, name and claim matches the original. Send the draft to a reader who knows the subject and ask one question: "Did I change what I meant?"

Human review catches meaning drift, which automated tools miss. Publish only after that check passes.

What are the most common mistakes?

Mistake 1: Making the text longer. Formal writing often gets wordy. Replace "in order to" with "to," and "due to the fact that" with "because." Shorter formal sentences read better than long ones.

Mistake 2: Changing the meaning. A strong word like "guaranteed" can soften into "likely" and lose the claim. Compare the original and revised versions side by side. If the claim changed, revert it.

Mistake 3: Using jargon to sound formal. Words like "leverage," "synergy" and "holistic" add no clarity. Choose plain words that a non-specialist understands. Formal means precise, not impressive.

Conclusion

Informal to formal writing is a set of edits: expand contractions, replace slang, cut filler, and make claims specific. Work through the steps in order, starting with marking the informal parts, then rebuilding sentences and checking tone for your channel. Keep the meaning fixed while you edit, and get one reader to confirm it. Pick your longest informal draft today and run the first two steps on one page.