Letâs look at a hypothetical spontaneous chemical reaction: The quantity of usable energy (chemical potential) in a reaction is called the Gibbs Free Energy (DG). DG is the difference between the energy contained in the products of a reaction and the reactants: DG = (energy of products) - (energy of reactants)
That's why some financial experts feel it's more realistic to think in terms of your net income, aka take-home pay, and that you shouldn't use any more than 25% of your take-home on your mortgage payment.
Household Debt to Income. The Federal Reserve Bank tracks how much of a U.S. household's income goes to pay its mortgage and other debts. In the first quarter of 2013, the average U.S. home-owning household paid 8.67 percent of its income in mortgage payments.