Is there any ratio of letters and images for the logo?

Question

Design

For example, 2/3, 1/3 caps, caps to the image?
Or some other proportion?

Answer 1

Take, for example, a portfolio of Lebedev Studio logos , find a logo with a similar shape (round, horizontally / vertically elongated, etc.) and a name similar in number of characters. Make your sign and your name in the same proportions. This is if you need it once and for yourself.

Answer 2

design is never made according to patterns
beauty cannot be described by formulas
to make a good design - you need a real good designer
everyone should do their own thing - otherwise it will be a mess and a madhouse