Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2020
Mar. 23, 2021
Mar. 22, 2021
Cover [Abstract]      
Entity Registrant Name FOCUS UNIVERSAL INC.    
Entity Central Index Key 0001590418    
Document Type 10-K    
Document Period End Date Dec. 31, 2020    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Is Entity a Well-known Seasoned Issuer? No    
Is Entity a Voluntary Filer? No    
Is Entity's Reporting Status Current? Yes    
Entity Filer Category Non-accelerated Filer    
Entity Emerging Growth Company true    
Entity Small Business true    
Entity Ex Transition Period false    
Entity Shell Company false    
Entity Public Float     $ 174,078,899
Entity Common Stock, Shares Outstanding   40,959,741  
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2020    
Entity Interactive Data Yes    
Entity Incorporation State NV    
Entity File Number 333-193087    
ICFR Auditor Attestation Flag false