Mortgage Calculator
Understanding what a home loan actually costs before you sign
A mortgage payment is made of two very different things bundled into one number: principal (paying down what you actually borrowed) and interest (the cost of borrowing it). Amortization is the schedule that determines how much of each monthly payment goes to each — and it isn't a flat split. Early in a loan's life, the vast majority of each payment goes toward interest, because interest is calculated on the outstanding balance, which starts at its highest point. As the balance shrinks over the years, the interest portion shrinks with it and more of each payment goes toward principal.
This structure is why the total interest paid over a 30-year loan can be startlingly close to — or even exceed — the amount originally borrowed, and why making extra principal payments early in a loan's term has an outsized effect on total interest compared to the same extra payment made later. It's also why two loans with the same monthly payment can have very different total costs depending on the rate and term.
Amortiq exists to make that math visible instantly — type in the loan amount, rate, and term, and see the monthly payment, total interest, and true total cost update as you type, entirely offline.
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Frequently asked questions
Why does so much of an early mortgage payment go to interest?
Because interest for a given month is calculated on the remaining loan balance, and early in a mortgage that balance is at its highest. As you pay down principal over time, the balance — and therefore the interest charged each month — shrinks, so a larger share of each fixed payment goes toward principal in later years. This is a structural feature of standard amortization, not specific to any lender.
Does paying extra toward principal actually save meaningful interest?
Yes, structurally — an extra principal payment reduces the balance that all future interest is calculated on, so it has a compounding effect over the remaining term. The earlier in the loan the extra payment is made, the more total interest it eliminates, since it removes that principal from a longer stretch of interest calculations. The exact savings depend on your specific rate, term, and remaining balance, which is why running the numbers for your own loan matters more than a general rule of thumb.
What's the difference between a mortgage calculator and a general loan calculator?
The underlying amortization math is the same, but mortgage-specific calculators often account for the much longer typical terms (15–30 years) and larger principal amounts involved in home loans, where the interest/principal split and the effect of extra payments are more dramatic than on a shorter auto or personal loan.