Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2022	May 16, 2022
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Trading Symbol	BIOC
Entity Registrant Name	Biocept, Inc.
Entity Central Index Key	0001044378
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Interactive Data Current	Yes
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		16,922,868
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-36284
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	80-0943522
Entity Address, Address Line One	9955 Mesa Rim Road
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	320-8200
Title of 12(b) Security	Common Stock, par value $.0001 per share
Entity Shell Company	false
Entity Current Reporting Status	Yes
Security Exchange Name	NASDAQ