I’m building a house and the builder has a number of incentives you can choose between. It led to me making my own (semi-vibe-coded) web app to compare different options and try out different combos (“What if I applied this ‘flex’ money to the house price or if used it to buy down the rate”). It was even easy to wire up Firebase for saving the data so it would sync between my phone and laptop.

One thing missing from this calculator (which doesn’t technically matter for calculating how much faster you’d pay down the mortgage) are HOA, taxes, and insurance. Again, that only matters if you want to calculate the total out of pocket monthly.

Update: A new version is out.

- Meihus now supports translations in 27 languages

- Auto-translation feature based on IP if the language is supported

- Manual language selector

The translations mechanism just looks for the IP country using ipapi, not storing any data about the user IP

Overall, love it. From the US perspective, property value and then down payment is an extra step when you could just start with total mortgage.

For user experience, the grey fields made me think they weren't editable or clickable until I got to the point of adding early payments.

my spouse and I used a spreadsheet for this purpose when we were house shopping. it also included local income and property taxes for all of the localities we'd choose to live in so we knew the full financial pros and cons of buying a specific house

because of it, we actually went with an area that had higher property taxes because the lower income taxes made up for it

lovely tool. Would be nice if there is an option to add repayment/reinvestment fee which my bank charges every time I do an early payment.

Thanks!