What is the formula use for Celsius?

There isn't a single formula "for Celsius." Celsius is a temperature scale, not a formula.

However, you might be asking about formulas involving Celsius:

* Converting Celsius to Fahrenheit:

* °F = (°C × 9/5) + 32

* Converting Celsius to Kelvin:

* K = °C + 273.15

* Converting Fahrenheit to Celsius:

* °C = (°F - 32) × 5/9

* Converting Kelvin to Celsius:

* °C = K - 273.15

Let me know if you had something else in mind!