Cover - shares	3 Months Ended
	Feb. 29, 2024	Apr. 11, 2024
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Feb. 29, 2024
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2024
Current Fiscal Year End Date	--11-30
Entity File Number	001-41945
Entity Registrant Name	LEGATO MERGER CORP. III
Entity Central Index Key	0002002038
Entity Tax Identification Number	98-1761148
Entity Incorporation, State or Country Code	E9
Entity Address, Address Line One	777 Third Avenue
Entity Address, Address Line Two	37th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10017
City Area Code	(212)
Local Phone Number	319-7676
Entity Current Reporting Status	No
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Elected Not To Use the Extended Transition Period	false
Entity Shell Company	true
Entity Common Stock, Shares Outstanding		25,799,375
Units, each consisting of one ordinary share and one-half of one redeemable warrant
Title of 12(b) Security	Units, each consisting of one ordinary share and one-half of one redeemable warrant
Trading Symbol	LEGT U
Security Exchange Name	NYSEAMER
Ordinary shares, par value $0.0001 per share
Title of 12(b) Security	Ordinary shares, par value $0.0001 per share
Trading Symbol	LEGT
Security Exchange Name	NYSEAMER
Redeemable warrants, exercisable for ordinary shares at an exercise price of $11.50 per share
Title of 12(b) Security	Redeemable warrants, exercisable for ordinary shares at an exercise price of $11.50 per share
Trading Symbol	LEGT WS
Security Exchange Name	NYSEAMER