| Document and Entity Information | Aug. 09, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 9, 2021 |
| Entity Registrant Name | Design Therapeutics, Inc. |
| Entity Central Index Key | 0001807120 |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-40288 |
| Entity Tax Identification Number | 82-3929248 |
| Entity Address, Address Line One | 6005 Hidden Valley Road |
| Entity Address, Address Line Two | Suite 110 |
| Entity Address, City or Town | Carlsbad |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92011 |
| City Area Code | 858 |
| Local Phone Number | 293-4900 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.0001 par value per share |
| Trading Symbol | DSGN |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | true |
