Calories (15 °C) to gallon-atmosphere (US) conversion calculator shown above calculates how many gallon-atmosphere (US) are in 'X' calories (15 °C) (where 'X' is the number of calories (15 °C) to convert to gallon-atmosphere (US)). In order to convert a value from calories (15 °C) to gallon-atmosphere (US) (from cal to gal atm) just type the number of cal to be converted to gal atm and then click on the 'convert' button.