Document and Entity Information - shares	3 Months Ended
	Apr. 30, 2017	May 31, 2017
Document And Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Apr. 30, 2017
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Trading Symbol	BOX
Entity Registrant Name	BOX INC
Entity Central Index Key	0001372612
Current Fiscal Year End Date	--01-31
Entity Filer Category	Large Accelerated Filer
Class A Common Stock
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		80,348,904
Class B Common Stock
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		52,449,596