binlog sizing (no replies)

Hello,

I am using NDB 7.1.22 and binlog format is mixed.

I wonder how to calculate the binlog writing speed (Mbytes/s) at a specific traffic.

Now I have two formula as below,
1) writing speed = row-data-size * throughput * ratio
ratio may be 1.2, 1.3, or 1.5
2) writing speed = (row-data-size + binlog-overhead) * throughput

which one is better?
do you know how to calculate RATIO or binlog-overhead?

Thanks

Alex