Most writers, at some point or another, wonder whether to use that or which.
You might try it one way and then another to see what sounds better, then you change it back, but something’s still wrong. So you add a comma or two, but that doesn’t sound right either. It’s enough to drive you batty!
Knowing when to use that or which is pretty simple, believe it or not. All you have to do is take a few minutes to learn the rules.
The short version of the rules for that or which
The long version means getting into pronouns and commas and all sorts of stuff to turn you into a grammar expert. But that’s probably not what you need right now, so here you go.
- Use that when referring to necessary (restrictive) information. Do not use commas.
- Use which when referring to unnecessary (non-restrictive) information. Use commas to set off that word or group of words.
“Restrictive” means the information limits (restricts) the meaning of the word or phrase it refers to.
“Non-restrictive” means the information doesn’t limit (does not restrict) the meaning of the word or phrase.
A few examples of that or which in sentences.
Imagine giving a friend directions to your home.
- The street that has bright red sidewalks is my street.
Bright red sidewalks identify the street, and it’s the only street that has them. This information restricts the meaning of “the street,” and it’s a feature your friend will rely upon.
- River Street, which has bright red sidewalks, is my street.
Here, the street name—River Street—is the identifying information about this particular street. “Bright red sidewalks” is extra or non-restrictive information. It’s kind of like saying, “By the way, River Street has bright red sidewalks.”
See how easy that is? I don’t know about you, but I like to stick with the rules because it keeps things simple.
The rules have an exception.
Some writers, especially British writers, tend to use which in the restrictive sense. That’s not usually a problem if the information is not set off with commas.
Clear: The street which has bright red sidewalks is my street.
The lack of commas helps clarify that it’s restrictive information, even though “that” is preferred over “which” in a case like this. Your friend, however, will know to look for bright red sidewalks, assuming he or she is close by.
Unclear: The street, which has bright red sidewalks, is my street.
As a test, remove the extra information (indicated by commas) “which has bright red sidewalks.” Without it, you’re left with “The street is my street.” Which street are you talking about and do other streets have bright red sidewalks? Is this the only one? This is how you can tell information is restrictive and that it shouldn’t have commas.
Remember how to use that or which with these mnemonics.
Mnemonics—memory aids—help you remember complex information. (Does anyone know a mnemonic for how to spell mnemonic?) Back in college, the first one below was a big help.
- That is important, but we can do without a “witch.”
- That comes before which in the alphabet, so it’s more important.
- Which is wishy-washy, and that’s that.
A few more examples of that or which.
Which ones are restrictive, and which are non-restrictive? (Answers are below.)
- I’d like to have the pie that has cherries on top. (That pie is the one I want—the pie with cherries—not any of the ones with blueberries or strawberries on top.)
- The pie my aunt baked, which had cherries on top, attracted some birds while we were away from our picnic table. (My aunt baked one pie, and it happened to have cherries on top.)
- The house that burned down last fall is finally getting cleared away. (The house that’s getting cleared is the one that burned down last fall.)
- The house, which had lovely flowers, burned down last fall. (The house that burned down just happened to have lovely flowers.)
- The flowers that grew near the house died from the heat of the fire. (Only the flowers near the house died.)
- The flowers, which grew near the house, died from the heat of the fire. (All the flowers died from the fire.)
And here’s a quick review.
Use “that” when the information it introduces is essential to the meaning. This is the restrictive sense and should not have commas.
On the other hand, use “which” when the information is non-essential to meaning. This is the non-restrictive sense, and you should set this information apart with commas to show it’s extra or “parenthetical” information (as if it’s in parentheses).
The difference in meaning between that and which and the words that come afterward can be obvious or subtle. But using that and which correctly—and commas as well—can make a big difference in your confidence and writing.
Information is based on The Chicago Manual of Style, 6.22, and the entry for “that; which” in the “Glossary of Problematic Words and Phrases.”
Answers to example sentences: 1. Restrictive 2. Non-restrictive 3. Restrictive 4. Non-restrictive 5. Restrictive 6. Non-restrictive.