Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

No definition available.

Name:	dei_AmendmentFlag
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

PCAOB issued Audit Firm Identifier

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 10-K
-Number 249
-Section 310

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 20-F
-Number 249
-Section 220
-Subsection f

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form 40-F
-Number 249
-Section 240
-Subsection f

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Aug. 30, 2025	Oct. 22, 2025	Feb. 28, 2025
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Aug. 30, 2025
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Entity Registrant Name	UNIFIRST CORPORATION
Entity Central Index Key	0000717954
Current Fiscal Year End Date	--08-30
Entity Filer Category	Large Accelerated Filer
Title of 12(b) Security	Common Stock, $0.10 par value per share
Trading Symbol	UNF
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Entity Interactive Data Current	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity File Number	001-08504
Entity Tax Identification Number	04-2103460
Entity Address, Address Line One	68 Jonspin Road
Entity Address, City or Town	Wilmington
Entity Address, State or Province	MA
Entity Incorporation, State or Country Code	MA
Entity Address, Postal Zip Code	01887
City Area Code	(978)
Local Phone Number	658-8888
ICFR Auditor Attestation Flag	true
Document Annual Report	true
Document Transition Report	false
Entity Public Float			$ 3,167,000,083
Documents Incorporated by Reference	Documents Incorporated By Reference The Registrant intends to file a Definitive Proxy Statement pursuant to Regulation 14A promulgated under the Securities Exchange Act of 1934, as amended, for its 2026 Annual Meeting of Shareholders within 120 days of the end of the fiscal year ended August 30, 2025. Portions of such Proxy Statement are incorporated by reference in Part III of this Annual Report on Form 10-K.
Auditor Name	Ernst & Young LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	42
Document Financial Statement Error Correction [Flag]	false
Auditor Opinion [Text Block]	Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of UniFirst Corporation and subsidiaries (the “Company”) as of August 30, 2025 and August 31, 2024, the related consolidated statements of income, comprehensive income, shareholders’ equity, and cash flows for each of the three years in the period ended August 30, 2025, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at August 30, 2025 and August 31, 2024, and the results of its operations and its cash flows for each of the three years in the period ended August 30, 2025, in conformity with U.S. generally accepted accounting principles. We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company’s internal control over financial reporting as of August 30, 2025, based on criteria established in Internal Control-Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework), and our report dated October 29, 2025 expressed an adverse opinion thereon.
Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		14,565,659
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		3,551,265