also: エンゼルけいすう
proportion of income spent on children; angel coefficient
Jocular term, a pun on エンゲル係数 (Engel coefficient). Used humorously to describe how much of a household's income goes toward child-related expenses.
See also: エンゲル係数
Our angel coefficient is high; the children's education costs are straining the household budget.
As the angel coefficient keeps rising, I can no longer spend money on my own hobbies.