Through vs. Thru: What's the Difference?
Learn when through is the standard spelling and when the informal variant thru is acceptable, with examples, style rules, a quiz, and FAQs.
Through is the standard spelling in formal and general writing. Thru is an informal shortened spelling used mainly in signs, brand names, messaging, and fixed expressions such as drive-thru. Unless space or an official name requires thru, choose through.
Working with a longer passage? Use our free AI text summarizer to turn it into a focused overview, then return here to check the wording.
A proposal promises support “thru every stage of implementation.” Because the document is formal and has no space constraint, the editor changes thru to through while leaving a quoted product name unchanged.
Through vs. Thru at a glance
| Word | Typical role | Meaning | Example |
|---|---|---|---|
| through | Preposition, adverb, or adjective | from one side or stage to another; during; completed | The team worked through the checklist before launch. |
| thru | Informal variant | a shortened spelling of through | The café has a drive-thru window. |
How to use through
Through is the conventional spelling across formal, academic, professional, and everyday prose. It can describe movement, duration, completion, connection, or a finished state.
The team worked through the checklist before launch.
How to use thru
Thru is widely recognized but stylistically limited. It is common where brevity matters, including signs, casual messages, commercial labels, and established compounds such as drive-thru.
The café has a drive-thru window.
Rules that make the choice easier
Default to through in edited prose
Reports, essays, instructions, and business communication normally use the full standard spelling through.
Use thru for space-limited or fixed wording
A road sign, interface label, or established expression may use thru for compactness. Preserve official names exactly.
Keep the style consistent
Do not alternate between through and thru in the same kind of sentence unless one occurrence belongs to a quoted or branded name.
Common mistakes to avoid
- Do not use thru merely because through looks long.
- Do not silently respell an official name such as a branded drive-thru service.
- Avoid mixing the two spellings in one document without a clear stylistic reason.
Quick practice
1. Which spelling belongs in a formal research report?
Answer: through
2. Which spelling is conventional in drive-___?
Answer: thru
3. Should an official product name be respelled?
Answer: No
Frequently asked questions
Is thru a correct spelling?
Thru is an accepted informal variant, but through is the standard spelling for edited prose.
Is it drive-through or drive-thru?
Both occur, though drive-thru is especially common in commercial names and signage.
Can I use thru in an email?
It may suit a very casual message, but through is clearer and more professional by default.
Is thru acceptable in academic writing?
Usually no. Academic writing normally requires the standard spelling through.