Document and Entity Information - shares
6 Months Ended
Jun. 30, 2019
Jul. 28, 2019
Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Trading Symbol PBPB  
Entity Registrant Name Potbelly Corporation  
Entity Central Index Key 0001195734  
Entity Current Reporting Status Yes  
Current Fiscal Year End Date --12-29  
Entity Filer Category Accelerated Filer  
Entity Shell Company false  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Common Stock, Shares Outstanding   23,768,375
Entity File Number 001-36104  
Entity Tax Identification Number 364466837  
Entity Address, Address Line One 111 N. Canal Street  
Entity Address, Address Line Two Suite 850  
Entity Address, City or Town Chicago  
Entity Address, State or Province Illinois  
Entity Address, Postal Zip Code 60606  
City Area Code 312  
Local Phone Number 951-0600