| Document and Entity Information | Aug. 16, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 16, 2021 |
| Entity Registrant Name | BIOCEPT, INC. |
| Entity Central Index Key | 0001044378 |
| Entity Emerging Growth Company | 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 |
| 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 | BIOC |
| Security Exchange Name | NASDAQ |
