Calpine
 | |
 | |
| Type | Private |
|---|---|
| Industry | Energy |
| Founded | 1984 |
| Founder | Peter Cartwright |
| Headquarters | , |
| Key people | |
| Revenue |  US$10.072 billion (2019) |
| US$770 million (2019) | |
| Total assets | US$16.062 billion (2018) |
| Owner | Constellation Energy |
Number of employees | 2,256 (2019) |
| Website | www |
Calpine Corporation was a Fortune 500 company based in Houston, Texas. It was the largest generator of electricity from natural gas and geothermal energy in the United States, with operations in competitive power markets.
In January 2026, Constellation Energy announced it had completed its acquisition of Calpine for $16.4 billion and that Calpine would become a business unit of Constellation.