v3.25.4
Document and Entity Information
 12 Months Ended
Dec. 31, 2025
shares
Document and Entity Information  
Document Type 20-F
Document Registration Statement false
Document Annual Report true
Document Period End Date Dec. 31, 2025
Current Fiscal Year End Date --12-31
Document Transition Report false
Document Shell Company Report false
Securities Act File Number 1-14878
Entity Registrant Name GERDAU S.A.
Entity Incorporation, State or Country Code D5
Entity Address, Address Line One Av. Dra. Ruth Cardoso
Entity Address, Address Line Two 8,501 – 8th floor
Entity Address, City or Town São Paulo
Entity Address, Country BR
Entity Address, Postal Zip Code 05425-070
Title of 12(b) Security Preferred Shares, no par value per share, each represented by American Depositary Shares
Trading Symbol GGB
Security Exchange Name NYSE
Entity Common Stock, Shares Outstanding 717,782,619
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 Emerging Growth Company false
ICFR Auditor Attestation Flag true
Document Financial Statement Error Correction [Flag] false
Document Accounting Standard International Financial Reporting Standards
Entity Shell Company false
Auditor Name PricewaterhouseCoopers Auditores Independentes Ltda.
Auditor Firm ID 1351
Auditor Location Porto Alegre, Brazil
Document Fiscal Year Focus 2025
Document Fiscal Period Focus FY
Entity Central Index Key 0001073404
Amendment Flag false