| Cover Page | Nov. 02, 2021 | Jan. 28, 2021 |
| Cover [Abstract] | ||
| Document Type | 8-K | |
| Document Period End Date | Nov. 2, 2021 | |
| Entity Registrant Name | 8X8 INC /DE/ | |
| Entity Incorporation, State or Country Code | DE | |
| Entity File Number | 001-38312 | |
| Entity Tax Identification Number | 77-0142404 | |
| Entity Address, Address Line One | 675 Creekside Way | |
| Entity Address, City or Town | Campbell | |
| Entity Address, State or Province | CA | |
| Entity Address, Postal Zip Code | 95008 | |
| City Area Code | 408 | |
| Local Phone Number | 727-1885 | |
| Title of 12(b) Security | COMMON STOCK, PAR VALUE $.001 PER SHARE | |
| Trading Symbol | EGHT | |
| Security Exchange Name | NYSE | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Entity Emerging Growth Company | false | |
| Entity Central Index Key | 0001023731 | |
| Amendment Flag | false |
