Document And Entity Information (USD $)
12 Months Ended
Aug. 31, 2012
Nov. 19, 2012
Feb. 29, 2012
Document and Entity Information [Abstract]      
Entity Registrant Name Northern Technologies International Corporation    
Document Type 10-K    
Current Fiscal Year End Date --08-31    
Entity Common Stock, Shares Outstanding   4,418,487  
Entity Public Float     $ 57,000,000
Amendment Flag false    
Entity Central Index Key 0000875582    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Smaller Reporting Company    
Entity Well-known Seasoned Issuer No    
Document Period End Date Aug. 31, 2012    
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus FY