Document And Entity Information - shares	9 Months Ended
	May 28, 2016	Jul. 01, 2016
Common Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding (in shares)		15,406,532
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding (in shares)		4,849,519
Entity Registrant Name	Unifirst Corp
Entity Central Index Key	0000717954
Trading Symbol	unf
Current Fiscal Year End Date	--08-27
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Document Type	10-Q
Document Period End Date	May 28, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q3
Amendment Flag	false