Cover Page - shares	9 Months Ended
	Sep. 30, 2022	Nov. 10, 2022
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Document Transition Report	false
Current Fiscal Year End Date	--12-31
Entity File Number	001-41526
Entity Registrant Name	CASTELLUM, INC.
Entity Central Index Key	0001877939
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	27-4079982
Entity Address, Address Line One	3 Bethesda Metro Center
Entity Address, Address Line Two	Suite 700
Entity Address, City or Town	Bethesda
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20814
City Area Code	301
Local Phone Number	961-4895
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	CTM
Security Exchange Name	NYSEAMER
Entity Current Reporting Status	No
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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		41,539,342