| Cover | Feb. 05, 2024 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 05, 2024 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
| Units, each consisting of one ordinary share, $0.0001 par value, and one-half of one redeemable warrant | |
| Title of 12(b) Security | Units, each consisting of one ordinary share, $0.0001 par value, 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 |
