Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 13, 2019
Document And Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Quarterly Report	true
Document Transition Report	false
Document Fiscal Period Focus	Q3
Entity Registrant Name	OPGEN INC
Entity Central Index Key	0001293818
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		5,582,268
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-37367
Entity Tax Identification Number	06-1614015
Entity Address, Address Line One	708 Quince Orchard Road
Entity Address, Address Line Two	Suite 205
Entity Address, City or Town	Gaithersburg
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20878
City Area Code	240
Local Phone Number	813-1260
Common Stock [Member]
Document And Entity Information [Line Items]
Trading Symbol	OPGN
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Common Warrants [Member]
Document And Entity Information [Line Items]
Trading Symbol	OPGNW
Title of 12(b) Security	Common Warrants
Security Exchange Name	NASDAQ