Hi,

What on average is a monitors SVL to TL.

According to resources online the tail lenght of a monitor is 2/3
Of its total lenght.

Then other websites have the tail lenght half of the monitors total lenght.

Also is it different between species I.e between Bosc, water, komodo etc.

Thanks,

Yes, every species of monitor has a different SVL to TL ratio.
Every individual within each species has a slightly different SVL to TL ratio, within the limits for its species.