| Document And Entity Information | Mar. 28, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 28, 2024 |
| Entity Registrant Name | 5E ADVANCED MATERIALS, INC. |
| Entity Central Index Key | 0001888654 |
| Entity Emerging Growth Company | true |
| Entity File Number | 001-41279 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 87-3426517 |
| Entity Address, Address Line One | 9329 Mariposa Road, Suite 210 |
| Entity Address, City or Town | Hesperia |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92344 |
| City Area Code | (442) |
| Local Phone Number | 221-0225 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Ex Transition Period | true |
| Title of 12(b) Security | Common stock, $0.01 par value per share |
| Trading Symbol | FEAM |
| Security Exchange Name | NASDAQ |
