Tone mostly comes down to distance. Formal language keeps the reader at arm's length: respectful, careful and a little impersonal. Casual language brings them closer. Neither is better in general. The skill is choosing the right distance for this reader, this channel and what's at stake. If you get it wrong, the mismatch becomes the message. Too formal suggests "we are not friends," and too casual suggests "I'm not taking this seriously."
One request, five ways
Here's the same request, asking someone to review a document, at five points on the scale:
"I would be grateful if you could review the attached document at your earliest convenience and advise of any required amendments."
"Could you review the attached draft when you have a chance? I'd like to finalize it by Friday."
"When you get a sec, can you look over this draft? Hoping to wrap it up Friday."
"Mind giving this a quick look? Want to ship it Friday."
"yo can you skim this real quick 🙏"
Read them in order and you can see the distance shrink. The softening words disappear ("would be grateful" → "could you" → "can you" → "mind" → nothing), sentences get shorter and punctuation loosens. Those are the real controls behind tone. You change formality mostly through hedging, sentence length and contractions, and much less through fancier vocabulary.
Four signals
When you're not sure which level to use, these four questions settle it:
- Audience: how well do you know them, and who is more senior? Unfamiliarity and seniority both push toward formal. Start any first message at level 2. You can always warm up later, but cooling down after starting too casual is awkward.
- Channel: where will they read it? Each medium has its own expectations. Words that are normal in chat look curt in email, and email-style formality pasted into chat feels chilly.
- Stakes: what happens if this gets screenshotted, forwarded, or reread during a dispute? High stakes push toward formal whatever the relationship. A salary conversation with a friendly manager still deserves level 2.
- Their lead: how do they write to you? Match their level, moving at most one step. If they sign off "cheers!" and use emoji, formal paragraphs from you will feel like a wall. If they write full paragraphs, a bare "np 👍" ("no problem") will look like a shrug.
If the signals disagree, for example a casual person but high stakes, go with the stakes. If you're stuck between two levels, pick the more formal one and add some warmth: "Could you review this by Friday? No rush before then, I know your week is packed."
Common mismatches
- Formal with your own team. Memo-style writing to people you work with every day comes across as cold or passive-aggressive, especially if it's a sudden change. People notice a sudden shift in tone and will ask what's wrong.
- Casual with someone's boss. Skipping levels because "they seem chill" is a risky bet. Let them go casual first.
- Casual bad news. "hey so small thing, we lost the Hendricks account lol." Bad news needs to be at least one level more formal than you'd normally be with that person.
- A formal apology for a casual mistake. A stiff corporate apology to a friend ("I regret any inconvenience caused") is worse than no apology. Match the apology to the relationship; see our guide to better ways of saying sorry.
Quick guide by channel
- Email to someone new: level 2. Full sentences, a greeting and a sign-off.
- Email to colleagues: level 2 to 3. Keep the structure but relax the wording.
- Slack or Teams: level 3 to 4. Sentence fragments are fine, and punctuation and emoji do a lot to set the tone.
- Text message: level 4 to 5, depending on the relationship more than the topic. Serious topics still deserve serious wording, even by text.
- Dating apps: level 4, with effort. Casual in tone, but use full words and ask specific questions. Low formality shouldn't look like low interest.
- Anything that could end up on record (HR matters, money, commitments): level 2 at least, whatever the channel.
The short version
If you remember nothing else: match their level, go one step more formal when the stakes rise, and don't surprise people with a sudden change in tone. If you've got the right sentence at the wrong level, you can type it into the BetterWayOfSaying tool and compare the Professional and Casual versions side by side.
Related guides
- How to Sound More Professional in Emails
- Better Way of Saying Thank You
- Better Way of Saying "Sounds Good" in Email
Not sure how your sentence comes across? Type it into BetterWayOfSaying.com and get three alternatives.