Widget plugin that lets me build quick styled loan calculators

I need to create 3 separate loan calculators each of which are really simple.

1 - Loan amount £1-£25k, 5% interest and let the user enter their monthly repayment amount then the tool should show how long the loan will take to repay. Max at 7 years if this this or above show a specific error message.

2 - Same Logic but the interest rates change depending on the loan amount, 3 bandings each with a different interest rate. Again just let the user pick a monthly repayment amount and show the loan period based on that.

3 - Exact same as Loan 1 but with a higher interest rate.

Doc attached for VERY rough design layout to show concept. Would need branded and styled to match the main website they'll be placed on. Ideally want this as a custom plugin that lets me create any of these 3 calcs assign it a shortcode and stick that widget on a page so I can update if interest rates etc change over time.