By poring it in a cup and the longer it fisses the more carbonation there is .
How Do I Test Soda For Carbonation?
I was told to just drink it and you can tell that way
Read the answers and try them all
If you have a can of soda I would shake the can at a temperature around 70 Fahrenheit and then open the can, if gas and liquid spew from the can it was carbonated.