How to calculate the number of years in a kalpa?
As far as I know, the words used in Buddhist Kalpa in a lot of cases, 

for example: Existence, life reduced (when life human destiny decreased from 84,000 years to 10 years),increased lifetime (as opposed to lifetime reduction),

Sub-Kalpa (approximately 16 million years),

Mid-Kalpa (20 sub-life),

Big-Kalpa (4 centered life = 1.3 billion years),

and countless Kalpa ..etc