Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2024	Mar. 10, 2025	Jun. 28, 2024
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2024
Document Transition Report	false
Entity File Number	001-04321
Entity Registrant Name	CASTELLUM, INC.
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	27-4079982
Entity Address, Address Line One	1934 Old Gallows Road
Entity Address, Address Line Two	Suite 350
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	752-6157
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	CTM
Security Exchange Name	NYSEAMER
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 11,601,967
Entity Common Stock, Shares Outstanding		80,391,874
Documents Incorporated by Reference	The information required by Part III (Items 10, 11, 12, 13 and 14) of this Annual Report on Form 10-K, to the extent not set forth herein, is incorporated herein by reference from the registrant's definitive proxy statement relating to the Annual Meeting of Shareholders to be held in 2025, which definitive proxy statement shall be filed with the Securities and Exchange Commission within 120 days after the end of the fiscal year to which this Annual Report on Form 10-K relates
Entity Central Index Key	0001877939
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false