| Cover | Jan. 24, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | May 15, 2024 |
| Entity Registrant Name | CASTELLUM, INC. |
| Entity Incorporation, State or Country Code | NV |
| Entity File Number | 001-41526 |
| Entity Tax Identification Number | 27-4079982 |
| Entity Address, Address Line One | 1934 Old Gallows Road, Suite |
| Entity Address, City or Town | Vienna |
| Entity Address, State or Province | VA |
| Entity Address, Postal Zip Code | 22182 |
| City Area Code | 703 |
| Local Phone Number | -6157 |
| 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 $0.0001 per share |
| Trading Symbol | CTM |
| Security Exchange Name | NYSEAMER |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | true |
| Entity Central Index Key | 0001877939 |
| Amendment Flag | false |
