Thursdays or Thursday's: Which One Is Correct?

Unlike a right-versus-wrong spelling, Thursdays and Thursday's are both correct forms, they simply signal different things, and picking the wrong one changes the meaning. Thursdays, with no apostrophe, is the plural of Thursday and also the word for something that happens habitually: "we meet on Thursdays," "the last two Thursdays were quiet." Thursday's, with an apostrophe before the s, is either the possessive, "Thursday's schedule" (the schedule belonging to Thursday), or a contraction of Thursday is, "Thursday's going to rain." So the choice is not about spelling a word right, but about whether you mean more than one Thursday (no apostrophe) or possession / Thursday is (apostrophe). This places Thursdays vs Thursday's among the commonly confused words where an apostrophe gets added, or dropped, in the wrong place. This guide explains when each form is right, why the apostrophe causes trouble, and a simple test to choose correctly every time.

Which One Do You Mean?

Because both forms are valid, the question is not "which is correct?" but "which job do you need the word to do?" There are three possibilities, and the apostrophe (or its absence) tells them apart.

If you mean more than one Thursday, or something that happens regularly on that day, use Thursdays, with no apostrophe. "The class runs on Thursdays," "there are five Thursdays this month." This is the plain plural, and days of the week form their plurals exactly like ordinary nouns, by adding s.

If you mean something belonging to Thursday, use Thursday's, with the apostrophe before the s. "Thursday's game was postponed," "I read Thursday's paper." Here the apostrophe marks possession, the game or paper of Thursday.

If you are writing a contraction of Thursday is, also use Thursday's. "Thursday's my day off" means "Thursday is my day off." The apostrophe stands in for the missing letter i in is.

The practical rule of thumb: an apostrophe signals possession or a missing letter, never a plural. If all you are doing is counting days, more than one Thursday, drop the apostrophe and write Thursdays. Reach for Thursday's only when Thursday owns something or when you could expand it to Thursday is.

Why the Apostrophe Causes Trouble

If the rule is that simple, why do Thursday's and Thursdays get mixed up so often? The confusion comes from a few predictable habits.

The biggest is the urge to add an apostrophe before any final s. Many writers feel that a lone s looks "bare," so they insert an apostrophe out of caution, producing Thursday's when they only mean the plural Thursdays. This is so common in shop signs ("open Sunday's") that it has a nickname: the greengrocer's apostrophe. It is still an error.

A second cause is that the possessive and the plural sound identical. Spoken aloud, Thursdays and Thursday's are the same, so the ear gives no clue about whether an apostrophe belongs. The decision has to be made on meaning, not sound.

A third factor is the contraction overlap. Because Thursday's can legitimately mean Thursday is, writers see the apostrophe-s form often and start using it everywhere, including where a plain plural is needed. The cure is not a better ear but a quick meaning test: is Thursday owning something, or standing for Thursday is? If neither, it is just Thursdays.

Examples in Sentences

Seeing each form in its own role, with the error corrected, makes the difference clear.

Correct uses of Thursdays (plural / habitual):

• The market is held on Thursdays.
• We had three rainy Thursdays in a row.
• She teaches on Tuesdays and Thursdays.

Correct uses of Thursday's (possessive):

• Thursday's meeting has been moved to noon.
• Did you see Thursday's headline?
• Thursday's weather looks perfect.

Correct uses of Thursday's (contraction of Thursday is):

• Thursday's going to be a long day.
• I think Thursday's the best option.

Wrong → right corrections:

• The gym is open on Thursday's. → The gym is open on Thursdays.
• We skipped the last two Thursday's. → We skipped the last two Thursdays.
• Thursdays forecast is grim. → Thursday's forecast is grim.

In each correction, the apostrophe is added only where there is possession or a contraction, and dropped where the word is a plain plural.

Thursdays vs Thursday's: Side by Side

The table sets the forms against each other.

Form	Job	Apostrophe?	Example
Thursdays	plural / habitual	no	open on Thursdays
Thursday's	possessive	yes, before s	Thursday's plan
Thursday's	contraction (Thursday is)	yes, before s	Thursday's here
Thursdays'	plural possessive	yes, after s	three Thursdays' totals

The key column is "job": if you only mean more than one day, you want Thursdays with no apostrophe. Every apostrophe form is doing something extra, owning or shortening, not just counting.

How to Remember

The cleanest trick is a single question: what is the apostrophe for? An apostrophe only ever marks possession (Thursday's plan) or a missing letter (Thursday's here = Thursday is). If neither applies, and you just mean several Thursdays, there is nothing for an apostrophe to do, so leave it out: Thursdays.

A second cue: try to expand it to Thursday is. "Thursday's my day off" expands cleanly to "Thursday is my day off," so the apostrophe is right. "Open on Thursday's" cannot expand to "open on Thursday is," so the apostrophe is wrong, it should be Thursdays. The same logic sorts out any day of the week, and it lines up with other apostrophe puzzles like don'ts or dont's, where the apostrophe again has to earn its place, and with number-and-date forms such as 13rd vs 13th. Ask what the mark is doing, and you will place it correctly.

Conclusion

Thursdays and Thursday's are both correct, but they are not interchangeable. Thursdays, with no apostrophe, is the plural and the habitual form, "open on Thursdays," "three Thursdays in a row." Thursday's, with an apostrophe before the s, marks possession, "Thursday's meeting," or stands in for Thursday is, "Thursday's a holiday." The rare Thursdays', apostrophe after the s, is the plural possessive. The forms get muddled because writers add an apostrophe before any s out of habit (the greengrocer's apostrophe), because plural and possessive sound identical, and because the Thursday is contraction makes the apostrophe-s form feel normal everywhere. The fix is one question: is the apostrophe marking ownership or a missing letter? If not, you just mean Thursdays. Apply that test and you will choose correctly every time. For more pairs where an apostrophe lands in the wrong place, browse the full collection of commonly confused words.