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.
When you take out your mortgage, 30 years might seem like a long time away. Depending on how you treat your mortgage, you could pay it off in less time or, if you are like many people, you will take more than 30 years to pay off the mortgage. The amount of time it takes you to pay off your mortgage doesn't really depend on the term of the mortgage.