Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

Document and Entity Information - shares
9 Months Ended
Sep. 26, 2020
Nov. 05, 2020
Cover [Abstract]    
Document Type 10-Q  
Document Period End Date Sep. 26, 2020  
Entity Registrant Name CARPARTS.COM, INC.  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Entity Interactive Data Current Yes  
Smaller Reporting Company true  
Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   47,926,738
Current Fiscal Year End Date --01-02  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q3  
Entity Central Index Key 0001378950  
Amendment Flag false  
Title of 12(g) Security Common Stock, $0.001 par value per share  
Trading Symbol PRTS  
Security Exchange Name NASDAQ