Cover
| Cover | Aug. 16, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 16, 2021 |
| Entity File Number | 1-14120 |
| Entity Registrant Name | Blonder Tongue Laboratories, Inc. |
| Entity Central Index Key | 0001000683 |
| Entity Tax Identification Number | 52-1611421 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | One Jake Brown Road |
| Entity Address, City or Town | Old Bridge |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 08857 |
| City Area Code | (732) |
| Local Phone Number | 679-4000 |
| 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 $.001 |
| Trading Symbol | BDR |
| Security Exchange Name | NYSEAMER |
| Entity Emerging Growth Company | false |