| Cover | Mar. 22, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 22, 2022 |
| Entity File Number | 000-50099 |
| Entity Registrant Name | Grapefruit USA, Inc. |
| Entity Central Index Key | 0001205181 |
| Entity Tax Identification Number | 95-4451059 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1000 Northwest Street |
| Entity Address, Address Line Two | Mid-Town Brandy Wine |
| Entity Address, Address Line Three | Suite 1200-3094 |
| Entity Address, City or Town | Wilmington |
| Entity Address, State or Province | DE |
| Entity Address, Postal Zip Code | 19801 |
| City Area Code | (310) |
| Local Phone Number | 575-1175 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
