Where does the discount rate come from?

I don’t have a one-stop-shop calculator for you. But here’s how you can do it.

(1) Calculate the difference in monthly mortgage payments using a mortgage calculator like this one to estimate the future mortgage payment.
https://www.mortgagecalculator.org/
(2) use an NPV calculator to discount the difference to today’s $$. For example, 300 months with a $1,000/month difference translates to about $50k NPV assuming a 2% discount rate.

https://www.calculator.net/present-value-calculator.html

Good luck!

Does anyone have a resource on how to calculate relocation expenses that would include the interest rates rather than just the moving and closing costs?

I have a job offer in Ohio that would require us to relocate from Bethesda. While the cost of living is generally lower, that difference is less in the neighborhoods with the better school system similar to Bethesda. We currently have a 2.4% interest rate which will shoot up if we buy a new house. Is there a resource I can use to compare the numbers? I would be able to offset some of the rate by putting the gain from my house sale into the purchase of a new house.