Document and Entity Information - shares	6 Months Ended
	Jun. 28, 2019	Jul. 31, 2019
Document And Entity Information [Abstract]
Trading Symbol	HCKT
Entity Registrant Name	HACKETT GROUP, INC.
Entity Central Index Key	0001057379
Document Type	10-Q
Document Period End Date	Jun. 28, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-27
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		29,856,247
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity File Number	333-48123
Entity Tax Identification Number	650750100
Entity Address, Address Line One	1001 Brickell Bay Drive
Entity Address, Address Line Two	Suite 3000
Entity Address, City or Town	Miami
Entity Address, State or Province	Florida
Entity Address, Postal Zip Code	33131
City Area Code	305
Local Phone Number	375-8005