| Document and Entity Information Document | Oct. 22, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 22, 2020 |
| Entity Registrant Name | UNITED NATURAL FOODS, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-15723 |
| Entity Tax Identification Number | 05-0376157 |
| Entity Address, Address Line One | 313 Iron Horse Way, |
| Entity Address, City or Town | Providence, |
| Entity Address, State or Province | RI |
| Entity Address, Postal Zip Code | 02908 |
| City Area Code | 401 |
| Local Phone Number | 528-8634 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, par value $0.01 |
| Trading Symbol | UNFI |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001020859 |
| Amendment Flag | false |
