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.
Jun 18, '12. A good way to estimate take home pay is about 75% of gross, meaning plan on 25% of your salary going to payroll taxes. Maybe a little conservative for some but better safe than sorry. I do HR in Southern CA right now and this is what I usually advise my friends and family. Jul 18, '12.