| Document and Entity Information | Mar. 15, 2022 |
| Cover [Abstract] | |
| Entity Incorporation State Country Code | DE |
| Entity Address, State or Province | TX |
| Amendment Flag | false |
| Entity Central Index Key | 0001888654 |
| Document Type | 8-K |
| Document Period End Date | Mar. 15, 2022 |
| Entity Registrant Name | 5E ADVANCED MATERIALS, INC. |
| Entity File Number | 001-41279 |
| Entity Tax Identification Number | 87-3426517 |
| Entity Address, Address Line One | 19500 STATE HIGHWAY 249 |
| Entity Address, Address Line Two | SUITE 125 |
| Entity Address, City or Town | HOUSTON |
| Entity Address, Postal Zip Code | 77070 |
| City Area Code | (346) |
| Local Phone Number | 439-9656 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock |
| Trading Symbol | FEAM |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
