| Document and Entity Information | May 14, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Entity Registrant Name | CANDEL THERAPEUTICS, INC. |
| Amendment Flag | false |
| Entity Central Index Key | 0001841387 |
| Document Period End Date | May 14, 2024 |
| Entity Incorporation State Country Code | DE |
| Securities Act File Number | 001-40629 |
| Entity Tax Identification Number | 52-2214851 |
| Entity Address, Address Line One | 117 Kendrick St |
| Entity Address, Address Line Two | Suite 450 |
| Entity Address, City or Town | Needham |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02494 |
| City Area Code | (617) |
| Local Phone Number | 916-5445 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.01 par value per share |
| Trading Symbol | CADL |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
