| Cover | Oct. 28, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | AEMETIS, INC. |
| Entity Central Index Key | 0000738214 |
| Document Type | 8-K |
| Amendment Flag | false |
| Current Fiscal Year End Date | --12-31 |
| Entity Emerging Growth Company | false |
| Document Period End Date | Oct. 28, 2021 |
| Entity File Number | 001-36475 |
| Entity Incorporation State Country Code | DE |
| Entity Tax Identification Number | 26-1407544 |
| Entity Address Address Line 1 | 20400 Stevens Creek Blvd. |
| Entity Address Address Line 2 | Suite 700 |
| Entity Address City Or Town | Cupertino |
| Entity Address State Or Province | CA |
| Entity Address Postal Zip Code | 95014 |
| City Area Code | 408 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Local Phone Number | 213-0940 |
| Security 12b Title | Common Stock, par value $0.001 per share |
| Trading Symbol | AMTX |
| Security Exchange Name | NASDAQ |
