Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 04, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Interactive Data Current	Yes
Trading Symbol	FBRX
Entity Current Reporting Status	Yes
Entity Registrant Name	FORTE BIOSCIENCES, INC.
Entity Central Index Key	0001419041
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity File Number	001-38052
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-1243872
Entity Address, Address Line One	1124 W Carson Street
Entity Address, Address Line Two	MRL Building 3-320
Entity Address, City or Town	Torrance
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90502
City Area Code	310
Local Phone Number	618-6994
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		14,754,557