The ratio of these elements in carbohydrates is typically 1:2:1, meaning that for every carbon atom there are two hydrogen atoms and one oxygen atom. This is represented by the general formula (CH₂O)ₙ, where 'n' represents the number of repeating units.

This ratio is why the term "carbohydrate" was coined - "carbo" for carbon and "hydrate" for water (H₂O). While the 1:2:1 ratio is common, there are some exceptions, such as deoxyribose (C₅H₁₀O₄) which is found in DNA.