| Cover | Apr. 21, 2023 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Apr. 21, 2023 |
| Entity File Number | 001-40706 |
| Entity Registrant Name | Blue Whale Acquisition Corp I |
| Entity Central Index Key | 0001854863 |
| Entity Tax Identification Number | 98-1590107 |
| Entity Incorporation, State or Country Code | E9 |
| Entity Address, Address Line One | PO Box 1093 |
| Entity Address, Address Line Two | Boundary Hall |
| Entity Address, City or Town | Cricket Square |
| Entity Address, Country | KY |
| Entity Address, Postal Zip Code | KY1-1102 |
| City Area Code | (345) |
| Local Phone Number | 949-8066 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
| Entity Address, Region | Grand Cayman |
| Units, each consisting of one share of Class A common stock and one-fourth of one redeemable warrant | |
| Title of 12(b) Security | Units, each consisting of one share of Class A common stock and one-fourth of one redeemable warrant |
| Trading Symbol | BWCAU |
| Security Exchange Name | NASDAQ |
| Class A common stock, par value $0.0001 per share | |
| Title of 12(b) Security | Class A common stock, par value $0.0001 per share |
| Trading Symbol | BWC |
| Security Exchange Name | NASDAQ |
| Redeemable warrants, each whole warrant exercisable for one share of Class A common stock at an exercise price of $11.50 | |
| Title of 12(b) Security | Redeemable warrants, each whole warrant exercisable for one share of Class A common stock at an exercise price of $11.50 |
| Trading Symbol | BWCAW |
| Security Exchange Name | NASDAQ |
