| Document and Entity Information | Dec. 01, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | Twist Bioscience Corp |
| Amendment Flag | false |
| Entity Central Index Key | 0001581280 |
| Document Type | 8-K |
| Document Period End Date | Dec. 1, 2021 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-38720 |
| Entity Tax Identification Number | 46-2058888 |
| Entity Address, Address Line One | 681 Gateway Boulevard |
| Entity Address, City or Town | South San Francisco |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94080 |
| City Area Code | (800) |
| Local Phone Number | 719-0671 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock |
| Trading Symbol | TWST |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
