| Document and Entity Information | Jan. 29, 2025 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001871638 |
| Document Type | 8-K |
| Document Period End Date | Jan. 29, 2025 |
| Entity Registrant Name | Blaize Holdings, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-41139 |
| Entity Tax Identification Number | 86-2708752 |
| Entity Address, Address Line One | 4659 Golden Foothill Parkway |
| Entity Address, Address Line Two | Suite 206 |
| Entity Address, City or Town | El Dorado Hills |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 95762 |
| City Area Code | (916) |
| Local Phone Number | 347-0050 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Common Stock Par Value 0.0001 Per Share [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common stock, par value $0.0001 per share |
| Trading Symbol | BZAI |
| Security Exchange Name | NASDAQ |
| Warrants Each Whole Warrant Exercisable For One Share Of Common Stock At An Exercise Price Of 11.50 Per Share [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Warrants, each whole warrant exercisable for one share of Common stock at an exercise price of $11.50 per share |
| Trading Symbol | BZAIW |
| Security Exchange Name | NASDAQ |
