Cover Page - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Nov. 18, 2022	Mar. 31, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Sep. 30, 2022
Current Fiscal Year End Date	--09-30
Document Transition Report	false
Entity File Number	001-38720
Entity Registrant Name	Twist Bioscience Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-2058888
Entity Address, Address Line One	681 Gateway Blvd
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
Title of 12(b) Security	Common Stock
Trading Symbol	TWST
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 2,390
Entity Common Stock, Shares Outstanding		56,568,420
Documents Incorporated by Reference	Portions of the Registrant’s definitive proxy statement to be filed in connection with its 2023 Annual Meeting of Stockholders are incorporated by reference into Part III of this Form 10-K.
Amendment Flag	false
Entity Central Index Key	0001581280
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY