How many bytes for a publish string

Cloud
1

My data usage seems higher than expected. How many bytes are used to publish a string like this which publishes max temperature and a time stamp?
{“ts”:1526862295,“tx”:77,“fx”:1526849909}

I think this would take 19 bytes for the text characters and 12 bytes for the numbers (assuming all integers are 4 bytes).

2

I had this saved from awhile back about data usage:

image
image1416×652 65.5 KB

3

Thanks. that extra overhead for pings adds up to 230k/month.