Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information - USD ($)
$ in Millions
12 Months Ended
Jan. 02, 2021
Mar. 09, 2021
Jun. 26, 2020
Cover [Abstract]      
Document Type 10-K    
Document Period End Date Jan. 02, 2021    
Entity Registrant Name CARPARTS.COM, INC.    
Title of 12(g) Security Common Stock, $0.001 par value per share    
Trading Symbol PRTS    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Accelerated Filer    
Entity Interactive Data Current Yes    
Smaller Reporting Company true    
Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Entity Shell Company false    
Entity Common Stock, Shares Outstanding   48,092,549  
Entity Public Float     $ 229.9
Current Fiscal Year End Date --01-02    
Document Fiscal Year Focus 2020    
Document Fiscal Period Focus FY    
Entity Central Index Key 0001378950    
Amendment Flag false