WiFi (Wi-Fi)

Short answer: Use Wi-Fi (capital W and F, with a hyphen) in formal, published, or shared writing. WiFi or wifi is common in casual messages, but be consistent.

Quick answer

Default to Wi-Fi for professional, academic, and public-facing text. Reserve WiFi or wifi for quick, informal chat.

Official: Wi-Fi - mirrors the Wi-Fi Alliance trademark and reads polished in documents.
Informal: WiFi or wifi - fine for texts, threads, and casual social posts.
If unsure for work or school, choose Wi-Fi and apply it consistently across the file.

Core explanation

Wi-Fi is a brand name from the Wi-Fi Alliance; the hyphen and capitals are part of that styling. The term's meaning doesn't change with spelling, but inconsistent forms look unedited in reports, proposals, and papers.

Treat Wi-Fi like a proper noun: use the official form in formal contexts.
In casual channels you can drop the hyphen, but pick one variant per document.

Hyphenation and spelling

Preferred (formal): Wi-Fi. Common informal: WiFi or wifi. Avoid mixed or spaced variants.

Good: Wi-Fi
Casual acceptable: WiFi, wifi
Bad: Wi-fi, wi-fi, Wi Fi, Wi- Fi

Wrong → Right: Wrong: Our office upgraded the WiFi last month. -
Right: Our office upgraded the Wi-Fi last month.
Wrong → Right: Wrong: Free wifi is available in the lobby. -
Right: Free Wi-Fi is available in the lobby.

Spacing and capitalization

Treat Wi-Fi like a proper noun: capitalize W and F when it stands alone and do not add spaces. Use it adjectivally as in "Wi-Fi network" without re-hyphenating.

Plural: Wi-Fi networks
Possessive: Wi-Fi's uptime
Adjective: the Wi-Fi network (not Wi-Fi-network)

Wrong → Right: Wrong: Connect to the Wi Fi network. -
Right: Connect to the Wi-Fi network.
Wrong → Right: Wrong: The wifi's signal is weak. -
Right: The Wi-Fi's signal is weak.

Keep terminology consistent

Small spelling differences make documents look unedited. Add a one-line style rule for Wi-Fi in team guidance and use a find-and-replace or style tool to enforce it.

Set a document rule: "Use Wi-Fi (capital W and F, hyphen) in all public and formal documents."
Run a global search for wifi, WiFi, Wi-Fi, Wi Fi and unify to the chosen form.

Real usage and tone

Relax the formal rule for casual chat, but stick to Wi-Fi in client emails, syllabi, manuals, and published content. Follow a client or publisher style guide if one exists.

Work (formal): Please connect to the Wi-Fi before the demo so we can share the screen.
Work (ticket): User reports intermittent Wi-Fi drops on the third floor; please investigate.
Work (spec): Access points must support dual-band Wi-Fi and WPA3.
School (syllabus): Students must use the campus Wi-Fi to download the datasets.
School (lab): Connect to the lab's Wi-Fi and open the VM image.
School (email): Contact IT if you need temporary Wi-Fi access during exams.
Casual (text): Can you send the cafe wifi password?
Casual (social): Hotel wifi is so slow tonight.
Casual (forum): My router drops Wi-Fi every 10 minutes; any firmware tips?

Examples: wrong/right pairs and rewrites

Copy-ready corrections and alternative rewrites that avoid the term or read more formally.

Wrong → Right: Wrong: I need to connect to the WiFi network before the demo. -
Right: I need to connect to the Wi-Fi network before the demo.
Wrong → Right: Wrong: The WiFi password is posted on the bulletin board. -
Right: The Wi-Fi password is posted on the bulletin board.
Wrong → Right: Wrong: If the WiFi drops, restart the router. -
Right: If the Wi-Fi drops, restart the router.
Wrong → Right: Wrong: Free wifi is available in the lobby. -
Right: Free Wi-Fi is available in the lobby.
Wrong → Right: Wrong: The new phones don't connect to the wifi properly. -
Right: The new phones don't connect to the Wi-Fi properly.
Wrong → Right: Wrong: WiFi speeds were slower after the update. -
Right: Wi-Fi speeds were slower after the update.
Rewrite (formal): Please connect to the wireless network before the presentation.
Rewrite (concise): Join the office Wi-Fi using the "CompanyGuest" credentials.
Rewrite (student): Use campus Wi-Fi to access course materials instead of mobile data.
Copy-paste (work): Please ensure presenters are connected to the Wi-Fi by 9:00 AM.
Copy-paste (school): The library Wi-Fi will be offline for maintenance Saturday evening.
Copy-paste (casual): Anyone else having hotel wifi issues?

How to fix sentences quickly

Four quick steps: identify every variant, choose the target (formal → Wi-Fi), replace consistently, then proofread possessives and adjectival phrases.

Find: wifi, WiFi, Wi-Fi, Wi Fi, wi-fi
Replace with your chosen form (recommendation: Wi-Fi for formal docs)
Check: "Wi-Fi network" and "Wi-Fi's" for correct punctuation and capitalization

Wrong: original draft: john mentioned on slack that the wifi in the conference room is unreliable.
Right: corrected: John mentioned on Slack that the Wi-Fi in the conference room is unreliable.
Rewrite:
Alternative: John reported intermittent access to the conference-room wireless network.

Grammar note

Plural, possessive, and adjectival uses follow normal English rules once you choose the form.

Plural: Wi-Fi → Wi-Fi networks
Possessive: Wi-Fi → Wi-Fi's uptime
Adjective: use "Wi-Fi" before a noun (the Wi-Fi network); don't re-hyphenate.

Correct: The Wi-Fi network's password expires monthly.
Correct: We need more Wi-Fi access points.

Similar mistakes to watch for

Standardize other tech terms while you fix Wi-Fi: email/e-mail, online/on-line, Bluetooth capitalization, and brand casing like iPhone.

Email: modern style prefers email (no hyphen).
Online: one word.
Bluetooth: capitalize B. iPhone: lowercase i, capital P (follow the brand).
Decide once for your document and apply a global replace to keep consistency.

Usage: Incorrect: Send an e-mail. -
Correct: Send an email.
Usage: Incorrect: bluetooth. -
Correct: Bluetooth.

FAQ

Is it WiFi or Wi-Fi?

The official, trademarked form is Wi-Fi (capital W and F, hyphen). WiFi and wifi are common informal alternatives; use Wi-Fi in formal contexts.

Can I use wifi in a student paper?

When in doubt, use Wi-Fi for papers and formal submissions. If an instructor allows informal style, wifi is acceptable-consistency matters most.

Should I change WiFi to Wi-Fi across a whole document?

Yes. Pick one form (preferably Wi-Fi for formal work) and replace all variants to present a polished document.

How do I type the hyphenated Wi-Fi quickly?

Type "Wi-Fi" with capitals and a hyphen. Set a text expansion or editor replace rule to auto-correct wifi or WiFi to Wi-Fi.

Why do some sites drop the hyphen?

Dropping the hyphen is a stylistic shortcut common in informal writing. The hyphenated form follows the Wi-Fi Alliance trademark and is safer for formal contexts.

Try your own sentence

Paste a sentence or paragraph into a checker and search for wifi, WiFi, and Wi-Fi. Context often shows the best form.

Want a fast consistency check?

Run a document-wide find for wifi, WiFi, Wi-Fi and unify to your chosen form. For teams, add a one-line style note: "Use Wi-Fi (capital W and F, hyphen) in all public and formal documents."