| Document And Entity Information | Oct. 12, 2023 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Oct. 12, 2023 |
| Entity Registrant Name | RELAY THERAPEUTICS, INC. |
| Entity Central Index Key | 0001812364 |
| Entity Emerging Growth Company | false |
| Securities Act File Number | 001-39385 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 47-3923475 |
| Entity Address, Address Line One | 399 Binney Street |
| Entity Address, City or Town | Cambridge |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02139 |
| City Area Code | (617) |
| Local Phone Number | 370-8837 |
| 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 | RLAY |
| Security Exchange Name | NASDAQ |
