Document and Entity Information - shares	6 Months Ended
	Jul. 31, 2019	Aug. 30, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jul. 31, 2019
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Trading Symbol	BOX
Entity Registrant Name	BOX INC
Entity Central Index Key	0001372612
Current Fiscal Year End Date	--01-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Class A Common Stock, $0.0001 par value per share
Security Exchange Name	NYSE
Entity File Number	001-36805
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-2714444
Entity Address, Address Line One	900 Jefferson Ave
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94063
City Area Code	877
Local Phone Number	729-4269
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		147,780,283