v3.26.1
Cover - shares
 6 Months Ended
Jun. 30, 2026
Aug. 07, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Entity File Number 001-42629  
Entity Registrant Name Factorial Energy Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 42-2967285  
Entity Address, Address Line One 805 Middlesex Turnpike  
Entity Address, City or Town Billerica  
Entity Address, State or Province MA  
Entity Address, Postal Zip Code 01821  
City Area Code 617  
Local Phone Number 315-9733  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Amendment Flag false  
Entity Central Index Key 0002049662  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Series A Common Stock, par value $0.00001 per share    
Document Information [Line Items]    
Title of 12(b) Security Series A Common Stock, par value $0.00001 per share  
Trading Symbol FAC  
Security Exchange Name NASDAQ  
Entity Common Stock, Shares Outstanding   91,510,501
Warrants, each whole warrant exercisable for one share of Series A Common Stock at an exercise price of $11.50    
Document Information [Line Items]    
Title of 12(b) Security Warrants, each whole warrant exercisable for one share of Series A Common Stock at an exercise price of $11.50  
Trading Symbol FACWW  
Security Exchange Name NASDAQ  
Series B Common stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   15,512,744