Amortization
Calculator.

1. Two views, one story.

The calculator gives you two ways to visualize the same loan. Payment over time (the default) plots every month of your loan as a smooth line graph — it's the best view to see how interest and principal trade places over the life of the loan. Year-by-year shows the same data as a stacked bar for each year — great for quickly comparing individual years.

Both views show the same three colors and tell the same underlying story — pick whichever feels easier to read.

2. Orange = interest. Green = principal. Blue = balance.

The orange line is the interest portion of each monthly payment — money gone to the bank forever. The green line is the principal portion — money that reduces your balance and becomes your equity. The blue line is the running loan balance — it starts at your full loan amount and drops to zero on the payoff date.

In month one, orange dominates — roughly 79% of your payment on a typical 5%+ loan goes to interest. By the final month, the split is flipped and almost every dollar is principal.

3. Drag the circle to explore any month.

On the Payment over time graph, the three dots sit on a draggable vertical line. Click anywhere on the graph — or grab and slide the line — to see the exact values for that specific month.

The summary card above the graph updates live as you drag: the calendar date, the interest paid that month, the principal paid that month, and the remaining loan balance. This is the fastest way to answer "how much equity will I actually have in year 5?" or "when do I finally owe less than $200,000?"

4. Watch for the crossover month.

The "crossover" is the month where the green line finally rises above the orange line — when more of your payment starts going to principal than to interest. On a 30-year loan at today's rates, it typically lands around year 16 to 17. On a 15-year loan at the same rate, it happens in year 7 or 8.

Before the crossover, most of your payment is rent for the money you borrowed. After it, you're finally building more wealth than you're paying the bank. This is one of the biggest arguments for either making extra principal payments early — or choosing a shorter loan term from the start.

5. Refinancing resets the schedule.

One sneaky thing most buyers don't realize: when you refinance into a new 30-year loan five years in, you start the schedule over from month one — back in the interest-heavy early months. Unless the rate drop is significant (usually 1% or more) and you plan to stay long enough to recoup closing costs, refinancing can quietly undo years of equity-building.

Before refinancing, model your break-even point with our home profit calculator — it factors in the refi reset.

Same payment every month, different breakdown.

When you take out a mortgage, you don't just pay back what you borrowed — you also pay interest. Amortization is the process of spreading those payments out evenly over time, so you pay the same amount every month for the life of the loan.

In month one, your $400,000 loan is huge, so the bank charges a lot of interest. Most of your payment goes to them. But as you slowly pay down the balance, the interest charge shrinks — and more of that same payment chips away at what you actually owe. By the end, almost your entire payment is pure principal.

The math behind every calculator.

Monthly payment uses the standard amortization formula:

M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]

Where P is loan amount, r is monthly rate (annual ÷ 12), and n is total months. This is the industry-standard formula used by every mortgage calculator. Our chart runs it year by year using the prospective method for remaining balance.

What affects your amortization the most.

Interest rate is the single biggest lever. A 1% lower rate can save you tens of thousands over the life of your loan. Even a small difference compounds fast over 30 years.

Loan term matters too. A 15-year mortgage builds equity twice as fast as a 30-year but the monthly payment is higher. A 30-year keeps payments lower but you pay far more interest overall.

Down payment changes everything. The more you put down, the smaller your loan, the less interest you pay every single month. A bigger down payment also means no PMI above 20% LTV.

Extra payments are your secret weapon. Even $100 a month extra goes 100% to principal — it can shave years off your loan and save thousands in interest. Your bank probably won't tell you this.

Why it matters when you sell.

If you sell early — say year 3 — most of your payments went to interest and you built very little equity. The longer you hold, the more of each payment goes to you instead of the bank. That's why the home profit calculator pairs so well with this one: together, they tell you whether selling makes financial sense.