| Document and Entity Information | Oct. 28, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | SANFILIPPO JOHN B & SON INC |
| Amendment Flag | false |
| Entity Central Index Key | 0000880117 |
| Document Type | 8-K |
| Document Period End Date | Oct. 28, 2020 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 0-19681 |
| Entity Tax Identification Number | 36-2419677 |
| Entity Address, Address Line One | 1703 North Randall Road |
| Entity Address, City or Town | Elgin |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60123-7820 |
| City Area Code | (847) |
| Local Phone Number | 289-1800 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $.01 par value per share |
| Trading Symbol | JBSS |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
