Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Mar. 15, 2022	Jun. 30, 2021
Document Information [Line Items]
Entity Central Index Key	0001036262
Entity Registrant Name	INTEST CORP
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2021
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	1-36117
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	22-2370659
Entity Address, Address Line One	804 East Gate Drive, Suite 200
Entity Address, City or Town	Mt. Laurel
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	08054
City Area Code	856
Local Phone Number	505-8800
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	INTT
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 174,755,944
Entity Common Stock, Shares Outstanding		10,956,872
Auditor Name	RSM US LLP
Auditor Location	Blue Bell, Pennsylvania
Auditor Firm ID	49