What inputs do I need to use the mortgage calculator?

You need four main inputs: home price, down payment percentage, interest rate, and loan term. Optionally, select your state for accurate property tax and insurance estimates.

How does the down payment affect my monthly payment?

A larger down payment reduces your loan amount and monthly payment. Putting down 20% or more eliminates PMI, saving $100-$400/month. On a $400,000 home, going from 10% to 20% down saves about $133/month in PMI alone.

GuidesMay 10, 2026·8 min read

How to Use Our Mortgage Calculator to Plan Your Monthly Payment

Q: What is the amortization schedule in the calculator?

The amortization schedule shows every year of your loan broken down into principal paid, interest paid, and remaining balance. In year 1 of a 30-year mortgage, about 85% of your payment goes to interest.

A complete step-by-step guide to understanding every input, reading your results, and making smarter home-buying decisions with our interactive calculator.

Disclosure: This article contains affiliate links. If you click one and take action, we may earn a commission at no extra cost to you. Learn more

1. Getting Started: What You'll Need

Before you open the Mortgage Calculator, take a moment to gather a few key numbers. You don't need to be pre-approved for a loan — estimates are perfectly fine. Here's what you'll want to have handy:

Target home price

What price range are you looking at? Start with what you think you can afford.

Down payment %

How much cash can you put down? 20% is the magic number (no PMI).

Current interest rate

Check Bankrate or Mortgage News Daily for today's 30-year fixed rates.

Your state

Property tax rates vary wildly — from 0.3% in Hawaii to 2.5% in New Jersey.

💡 Pro Tip

Don't stress about getting exact numbers. The beauty of an interactive calculator is that you can adjust and experiment freely. Start with rough estimates and refine as you go.

2. Home Price & Down Payment

These two inputs work together to determine your loan amount — the actual sum you'll be borrowing from the bank. Let's walk through each.

Home Price

This is the purchase price of the home. Drag the slider or type directly into the input field — you'll see your monthly payment update instantly. Try dragging from $400,000up to $500,000 and watch how much your monthly payment jumps.

Try it yourself:

In the calculator, set Home Price = $400,000 and note the monthly payment. Then drag up to $500,000. On a 30-year loan at 6.5% with 20% down, that extra $100,000 adds roughly $630/month to your payment!

Down Payment

You can enter your down payment as either a percentage or a dollar amount — both fields are synchronized. The calculator automatically adjusts one when you change the other.

A 20% down payment is the traditional benchmark because it lets you avoid Private Mortgage Insurance (PMI). PMI typically costs 0.3%–1.5% of your loan amount per year. On a $320,000 loan, that's an extra $80–$400/monthyou're paying for nothing but the bank's protection.

Try this scenario:

Set Home Price = $400,000. Drag Down Payment from 20% → 10%. Notice PMI appears in red in the payment breakdown! That's $133/month extra. Over 5 years, that's nearly $8,000 you could have saved by waiting for 20% down.

3. Interest Rate & Loan Term

These two inputs have the most dramatic impact on your long-term costs. Small changes here can save — or cost — you tens of thousands of dollars over the life of your loan.

Interest Rate

The interest rate is the cost of borrowing money, expressed as an annual percentage. As of mid-2026, 30-year fixed rates are hovering around 6.5%–7%. Your actual rate depends on your credit score, loan type, and down payment size.

The slider lets you adjust in 0.125% increments(⅛ of a percentage point). Even this seemingly tiny change matters. On a $320,000 loan:

Interest Rate	Monthly Payment	Total Interest	Monthly Difference
6.00%	$1,919	$370,683	—
6.50%	$2,023	$408,142	+$104
7.00%	$2,129	$446,428	+$210

See it live:

Drag the Interest Rate slider from 6% → 7%. Watch the monthly payment number flash red as it increases. The total interest paid jumps by over $75,000 — that's a nice car, or a year of college tuition.

Loan Term (Years)

Most home buyers choose between a 30-year or15-year mortgage. Our calculator supports any term from 1 to 40 years, so you can experiment freely.

30-Year Mortgage

$2,023/mo

Total interest: $408,142

✓ Lower monthly payment

✗ Much more interest paid

15-Year MortgageSave big!

$2,789/mo

Total interest: $181,989

✓ Save $226,153 in interest

✗ $766/month higher payment

💡 Key Insight

A 15-year mortgage saves you over $226,000 in interest on a $400k home at 6.5%, but requires $766 more per month. If you can afford the higher payment, it's one of the best financial moves you can make. Use our calculator to compare both side by side.

4. Location & Local Costs

Your monthly payment isn't just about the loan — property taxes, insurance, and HOA fees can add hundreds of dollars per month. Our calculator includes all of these, with state-specific defaults.

State Selector

Pick your state from the dropdown, and the calculator automatically fills in:

0.40%

Alabama property tax

$133/mo on $400k home

1.80%

Texas property tax

$600/mo on $400k home

2.40%

New Jersey property tax

$800/mo on $400k home

Try this comparison:

Select Alabama → monthly payment is about $2,490.
Switch to New Jersey → it jumps to $3,157.
That's a $667/month difference — just because of location!

Fine-Tuning: Insurance, HOA & PMI

Below the state selector, you can manually adjust property tax rate, insurance, and HOA fees. You'll also see PMI appear automatically when your down payment is below 20%. All of these feed into the Payment Breakdown donut chart, so you can see exactly where every dollar goes.

5. Reading Your Monthly Breakdown

Once you've dialed in your inputs, the right panel shows your Estimated Monthly Paymentin large type. Here's what each component means:

Principal & Interest

The core of your payment. Principal pays down what you borrowed; interest is the bank's fee. In the first year of a 30-year loan, roughly 75% of this portion goes to interest alone.

Property Tax

Paid to your local government, usually held in an escrow account by your lender. Varies dramatically by state and county.

Home Insurance

Required by your lender. Covers damage to your home from fire, storms, theft, etc. Typically $100–$300/month depending on location.

HOA Fees

Homeowners Association fees for shared amenities and maintenance. Can range from$0 to $500+/month. Leave at $0 if you're buying a single-family home.

PMI (if applicable)

Private Mortgage Insurance — shown in redwhen your down payment is under 20%. This is pure cost with no benefit to you. Try to avoid it if possible!

Visualize with the Donut Chart

The Payment Breakdown donut chart shows each component as a proportional slice. Hover over any slice to see its dollar value. It's a powerful way to quickly understand where your money is really going each month.

6. Understanding the Amortization Schedule

The amortization chart is one of the most eye-opening features of our calculator. It shows you the entire life of your loan — every year's principal paid, interest paid, and remaining balance.

The Stacked Area Chart

The blue gradient areas show two things layered together:

Dark blue (bottom layer): Cumulative principal paid — how much of the actual home you've earned ownership of.
Light blue (top layer): Cumulative interest paid — the total cost of borrowing.

The shocking truth about year 1

On a $400,000 home with 20% down at 6.5% over 30 years: In year one, you'll pay about$20,700 in interest but only $3,600 toward principal. That's nearly 85% pure interest. Click "View Details" under the chart to see this year-by-year breakdown in the amortization table.

The Amortization Table

Click "View Details" below the chart to expand the full amortization table. Every row shows a year of your loan:

Year	Principal Paid	Interest Paid	% to Interest	Remaining Balance
1	$3,567	$20,708	85%	$316,433
5	$22,041	$101,049	82%	$297,959
10	$48,853	$196,724	80%	$271,147
15	$80,311	$283,148	78%	$239,689
20	$117,767	$354,751	75%	$202,233
25	$163,699	$404,733	71%	$156,301
30	$320,000	$408,142	56%	$0

Notice how the % to Interest column starts at 85% in year 1 and gradually declines. By year 30, you've paid $408,142 in intereston top of your $320,000 loan — that's more in interest than the original loan amount!

7. Putting It All Together: Real-World Scenario

Let's walk through a complete example so you can follow along in the calculator:

🏠 Sarah's First Home — A Step-by-Step Walkthrough

Set Home Price to $350,000

Sarah is looking at a 3-bedroom home in Texas. She types 350,000 into the input field.

Set Down Payment to $70,000 (20%)

She's saved $70k. Notice PMI stays at $0 — that's the 20% benefit!

Set Interest Rate to 6.75%

Based on today's rates for her credit profile. She drags the slider to 6.75.

Set Loan Term to 30 years

She wants the lowest monthly payment initially—drag to 30.

Select Texas from the state dropdown

Property tax rate auto-fills to ~1.8%, insurance to $2,500/yr.

📊 Read the Results

Monthly payment: $2,603(Principal & Interest: $1,816 + Property Tax: $525 + Insurance: $208 + HOA: $53)

Sarah's alternative: What if she chooses 15 years?

If Sarah changes the loan term from 30→15 years, her payment jumps to $2,571/mo(just $235 more for P&I), but her total interest plummets from $353,625 to $166,220 — saving $187,405. That's the power of understanding your amortization!