Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Jul. 27, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-39655
Entity Registrant Name	GALECTO, INC.
Entity Central Index Key	0001800315
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	37-1957007
Entity Address, Address Line One	75 State Street
Entity Address, Address Line Two	Suite 100
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02109
City Area Code	+45
Local Phone Number	70 70 52 10
Title of 12(b) Security	Common Stock, par value $0.00001 per share
Trading Symbol	GLTO
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		25,395,697