One of the assumptions of ordinal utility theory is that

Ordinal utility theory is a theory used in microeconomics to explain how individuals make choices when faced with different options. One of the main assumptions of this theory is that utility can be ranked. This means that individuals can express a preference for one option over another based on the satisfaction they derive from each option. However, ordinal utility theory does not assume that utility can be measured in a precise or quantitative way, only that individuals can express a relative ranking of preferences.