v3.26.1
Document and Entity Information - shares
3 Months Ended
Jun. 30, 2026
Aug. 05, 2026
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2026  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Entity Registrant Name INTERNATIONAL BATTERY METALS LTD.  
Entity Central Index Key 0001786318  
Current Fiscal Year End Date --06-30  
Entity Current Reporting Status Yes  
Entity Interactive Data Current No  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Shell Company false  
Entity Ex Transition Period false  
Entity File Number 333-286616  
Entity Incorporation, State or Country Code Z4  
Entity Tax Identification Number 00-0000000  
Entity Address, Address Line One 12 Greenway Plaza  
Entity Address, Address Line Two Suite 1100  
Entity Address, City or Town Houston  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 77046  
City Area Code 832  
Local Phone Number 683-8839  
Document Quarterly Report true  
Document Transition Report false  
Entity Common Stock, Shares Outstanding   379,001,682