Document and Entity Information	6 Months Ended
	Jul. 02, 2011	Aug. 03, 2011
Entity Information
Entity Registrant Name	NANOMETRICS INC
Entity Central Index Key	0000704532
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Jul. 02, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		22,860,628