“The car, that is red, is mine.”
Commas signal a non-essential clause; ‘that’ introduces an essential one. They don’t belong together.
Usage Entry 09 / 1605 60-second read Everyday
That vs. Which
Essential versus extra — a comma decides.
The comparisoni
“The car that is red is mine.”
No commas, because the clause tells us which car. Essential info.
More examplesii
01
The proposal which she drafted last week was approved.
The proposal that she drafted last week was approved.
No commas = essential clause — it identifies WHICH proposal. Use ‘that.’
02
The proposal that was drafted last week, and which ran to 40 pages, was approved.
The proposal, which was drafted last week and ran to 40 pages, was approved.
With commas = extra info — the clause is background. Use ‘which.’
The ruleiii
¶
THAT: essential. WHICH: extra.
If the clause is required to identify the noun, use THAT (no commas). If it’s just extra info, use WHICH (with commas).
Notesiv
Regional
Strict in American editing — Chicago, AP, and most US house styles enforce that/which for restrictive vs non-restrictive clauses. British and Indian English are more relaxed; ‘which’ commonly does both jobs there.
Register
Formal — academic, legal, and journalistic writing follow the rule most closely. Conversation and informal prose drop it routinely.
Watch for
If the clause could be deleted without changing what the sentence refers to, it’s non-essential — set it off with commas and use WHICH.
Memory aidv
Remember it like this
Which can be whisked away (with the commas). That can’t.
A bit of historyvi
Fowler's 1926 proposal codified what was already a tendency in English prose. Earlier writers — Austen, Dickens, Eliot — used both freely. The American adoption hardened in mid-20th-century editorial culture (Strunk and White in 1959 echoed Fowler), and the rule has been carried forward by every major American style guide since. British usage has remained more relaxed; Indian English follows the British pattern in most newspapers.
In the wildvii
Real-world-style usage — how this looks in a sentence people would actually write.
- The book that won the Booker Prize was her second novel, which drew on her childhood.
- Any idea that survives the first draft is worth keeping — the rest, which usually lands in the bin, is noise.
Spottedviii
Specimens from the editorial inbox — lines that did, in fact, get published.
“The policy which applies to all employees has been updated.”
— A global HR memo, 2022 — in U.S. style, essential clause wants ‘that’ and no comma
“Features that you may not need, can be disabled.”
— A software onboarding tooltip, 2020 — the comma without parenthetical matches neither variant cleanly
Test yourselfix
Which is right (American English)?
Quick duel 4 questions · ~30 seconds
Which is right?