What is the ratio of the distance to Andromeda to the size of the observable universe?
36 thousand times.
The distance between us and Andromeda (I suppose you mean the galaxy) is 2.537 million of light years.
The distance between us and the most remote object observed is The diameter of the observable universe is 91 billion of light years. Then the ratio is
About 11 K.
Using radial expansion from BB event, through 13.6 billion light years
(bly), the size of the observable universe is 2 X 13.8 = 27.6 bly.
The distance of Andromeda is about 2.5 million light years.
So, the ratio is 27.6 B/2.5 M = 27600/2.5 = 11 K, nearly.