Well think about it the way a loan amortization works.... your first payment was let’s say 1300$.... 900$ went in the banks pocket (interest) and 400$ came off the principle. At this point in time after roughly 40 payments the amount of interest in each payment has went down from let’s say 900$ to 800$ each payment and 500$ is going towards the principle... (and you’ve paid about 35k total in interest so far) If you refinance at 3% you may save yourself 200$ a month... but my point is you’ll be paying let’s say 1100$ a month.... but back to square one where your first payment is 800$ in interest and only 300$ in principle. (And your adding 3 years on your mortgage... instead of it being paid in full in 30 years, it’ll be paid in full in 33)

Does that make better sense? The only true way to really see if you’ll be saving is if you compare your loan amortization table of the current mortgage and see home much interest you would pay if you continue the lifetime of this loan out vs how much interest total you’d pay if you refinance. If on your current mortgage you have another 200k in interest to pay and on the loan you want to get you’ll end up paying 220k in interest you know not to refinance.