Document And Entity Information
| Document And Entity Information | May 08, 2023 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | May 08, 2023 |
| Entity Registrant Name | Arcellx, Inc. |
| Entity Central Index Key | 0001786205 |
| Entity Emerging Growth Company | true |
| Securities Act File Number | 001-41259 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 47-2855917 |
| Entity Address, Address Line One | 25 West Watkins Mill Road |
| Entity Address, Address Line Two | Suite A |
| Entity Address, City or Town | Gaithersburg |
| Entity Address, State or Province | MD |
| Entity Address, Postal Zip Code | 20878 |
| City Area Code | 240 |
| Local Phone Number | 327-0603 |
| Entity Information, Former Legal or Registered Name | Not Applicable |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Ex Transition Period | false |
| Title of 12(b) Security | Common Stock, $0.001 par value per share |
| Trading Symbol | ACLX |
| Security Exchange Name | NASDAQ |