The phrase "vary based on" is commonly used when describing how something is not uniform and can differ depending on certain factors. However, there are many alternative phrases and words that can also be used to convey this meaning. Some examples include "subject to change," "dependent on," "contingent upon," "influenced by," "hinged on," "determined by," and "affected by." Each of these synonyms can provide a different nuance to the sentence and help to better describe the specific factors that are impacting the variation. Choosing the right synonym can add depth and clarity to your writing, and allow you to more accurately convey your intended meaning.