| Document And Entity Information | Nov. 10, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 10, 2021 |
| Entity Registrant Name | TSCAN THERAPEUTICS, INC. |
| Entity Central Index Key | 0001783328 |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Entity File Number | 001-40603 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 82-5282075 |
| 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 | 857 |
| Local Phone Number | 399-9500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Voting Common Stock, par value $0.0001 per share |
| Trading Symbol | TCRX |
| Security Exchange Name | NASDAQ |
