Mortgage Calculator

A mortgage calculator turns three loan figures — the amount borrowed, the annual interest rate, and the term in years — into the payment a home loan will actually demand each month. This calculator implements both repayment schemes that banks commonly offer. In the equal-installment method every monthly payment stays identical across the whole term, while in the equal-principal method the payment starts higher and declines month by month as the balance shrinks. Alongside the monthly payment it reports total interest, total repayment, and a complete month-by-month amortization schedule showing exactly what portion of each payment covers interest and what portion pays down the principal.

What this tool can do

• 🏦 Both repayment methods, equal installment and equal principal, in one view.
• 💰 The fixed monthly payment for either method.
• 📉 The total interest the loan will cost over its full term.
• 🧾 The total repayment sum, principal plus interest combined.
• 📅 A month-by-month schedule: payment, principal portion, interest portion, and remaining balance for every month.
• ⚖️ Direct comparison of the two methods, showing the trade-off between a lower monthly payment and lower total interest.

When would you use it

• 🏠 Comparing mortgage offers from two different banks before signing anything.
• 📈 Deciding whether a slightly higher monthly payment now is worth the interest saved over decades.
• 🧮 Estimating, before house-hunting, what monthly payment a given price will require.
• 💡 Choosing between the two repayment methods when applying.

The math runs entirely in your browser; loan figures never leave your device and nothing is saved. Keep in mind what this model does not include: the rate is assumed fixed for the whole term, so variable-rate or balloon structures are not represented, and property taxes, insurance, and lender fees are outside the calculation. Treat the result as a planning figure, and verify the actual figures with your lender.

The standard amortisation formula behind every bank quote:

M = P · r(1+r)^n / ((1+r)^n − 1)

• M monthly payment, P principal, n number of months.
• r is the MONTHLY rate: annual % divided by 12, then by 100 — quoting 6% as r=0.06 instead of 0.005 is the classic mistake that inflates payments twelvefold.
• Total interest = M × n − P; the schedule below splits every payment into interest and principal parts.