| Cover | Aug. 23, 2024 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 23, 2024 |
| Entity File Number | 001-40677 |
| Entity Registrant Name | PLUM ACQUISITION CORP. III |
| Entity Central Index Key | 0001845550 |
| Entity Tax Identification Number | 98-1581691 |
| Entity Incorporation, State or Country Code | E9 |
| Entity Address, Address Line One | 2021 Fillmore St. #2089 |
| Entity Address, City or Town | San Francisco |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94115 |
| City Area Code | 929 |
| Local Phone Number | 529-7125 |
| 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 |
| Class A ordinary shares included as part of the Units, par value $0.0001 per share | |
| Title of 12(b) Security | Class A ordinary shares included as part of the Units, par value $0.0001 per share |
| Trading Symbol | PLMJ |
| Security Exchange Name | NASDAQ |
| Redeemable warrants, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50 per share | |
| Title of 12(b) Security | Redeemable warrants, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50 per share |
| Trading Symbol | PLMJW |
| Security Exchange Name | NASDAQ |
| Units, each consisting of one Class A ordinary share and one-third of one redeemable warrant to acquire one Class A ordinary share | |
| Title of 12(b) Security | Units, each consisting of one Class A ordinary share and one-third of one redeemable warrant to acquire one Class A ordinary share |
| Trading Symbol | PLMJU |
| Security Exchange Name | NASDAQ |
