The mortgage side is the rate you already have
A dollar of principal you do not borrow anymore does not accrue interest at the note rate. That savings is contractual if the rate is fixed. It is not a market forecast.
Our payoff calculator shows the interest dollars saved. It does not convert them into an investment account.
The investment side is an assumption
The rent-versus-buy tool grows cash at a return you type. That same honesty applies here: a 7% stock assumption is not a promise, and it is not comparable to a mortgage rate until you decide how much risk and tax you are ignoring.
This site excludes the mortgage-interest deduction on purpose. Many households take the standard deduction, and the deduction is not a full refund of the interest.
| Choice | What you can know today |
|---|---|
| Extra principal | The note rate, if it is fixed |
| Investing | Only the assumption you type |
Calculators
Related guides
Sources
Common questions
Does the site recommend investing?
No. It shows mortgage interest under your inputs and labels market returns as assumptions.
What about the tax deduction?
It is omitted. If you itemize and know the marginal effect, you can think of the mortgage rate as slightly lower. We will not invent that rate for you.