v3.26.1
Document and Entity Information - shares
 3 Months Ended
Mar. 31, 2026
May 05, 2026
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2026  
Document Transition Report false  
Entity File Number 001-41949  
Entity Registrant Name Metagenomi Therapeutics, Inc.  
Entity Incorporation, State or Country Code DE  
Entity Address, Address Line One 5959 Horton Street  
Entity Address, Address Line Two 7th Floor  
Entity Address, City or Town Emeryville  
Entity Address, State or Province CA  
Entity Tax Identification Number 81-3909017  
Entity Address, Postal Zip Code 94608  
City Area Code 510  
Local Phone Number 871-4880  
Document Fiscal Year Focus 2026  
Title of 12(b) Security Common stock, par value $0.0001 per share  
Trading Symbol MGX  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period true  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   37,646,858
Entity Central Index Key 0001785279  
Current Fiscal Year End Date --12-31  
Amendment Flag false  
Document Fiscal Period Focus Q1