| Document And Entity Information | Dec. 09, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Dec. 9, 2021 |
| Entity Registrant Name | Leslie's, Inc. |
| Entity Central Index Key | 0001821806 |
| Entity Emerging Growth Company | false |
| Entity File Number | 001-39667 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 20-8397425 |
| Entity Address, Address Line One | 2005 East Indian School Road |
| Entity Address, City or Town | Phoenix |
| Entity Address, State or Province | AZ |
| Entity Address, Postal Zip Code | 85016 |
| City Area Code | (602) |
| Local Phone Number | 366-3999 |
| 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 $0.001 per share |
| Trading Symbol | LESL |
| Security Exchange Name | NASDAQ |
