| Cover | Feb. 24, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 24, 2022 |
| Entity Registrant Name | COMPASS PATHWAYS PLC |
| Entity Incorporation, State or Country Code | X0 |
| Entity File Number | 001-39522 |
| Entity Address, Address Line One | 33 Broadwick Street |
| Entity Address, City or Town | London |
| Entity Address, Postal Zip Code | W1F 0DQ |
| Entity Address, Country | GB |
| Country Region | 1 |
| City Area Code | 646 |
| Local Phone Number | 905-3974 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | American Depositary Shares, each representing one ordinary share, nominal value £0.008 per share |
| Trading Symbol | CMPS |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001816590 |
