| Document and Entity Information | Dec. 10, 2024 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001661998 |
| Document Type | 8-K |
| Document Period End Date | Dec. 10, 2024 |
| Entity Registrant Name | Q32 Bio Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-38433 |
| Entity Tax Identification Number | 47-3468154 |
| Entity Address, Address Line One | 830 Winter Street |
| Entity Address, City or Town | Waltham |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02451 |
| City Area Code | 781 |
| Local Phone Number | 999-0232 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common stock, par value $0.0001 per share |
| Trading Symbol | QTTB |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
