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Mortgage Calculator

Estimate your monthly home loan payment

See your monthly principal + interest payment on a fixed-rate mortgage. Adjust the loan amount, rate, and term to compare scenarios — 15, 20, or 30 years.

$
$100,000$100,000,000
%
1%20%
Yr
1 Yr30 Yr
Monthly EMI$2,528
Total Interest$510,178
Total Payment$910,178

How Mortgage Payments Work

A fixed-rate mortgage spreads your loan into equal monthly payments over the term. Each payment has two parts: interest on the outstanding balance, and principal that reduces what you owe. Early on, most of each payment is interest. In the final years, most is principal.

This calculator shows the principal + interest portion only (P&I). Your full monthly housing cost — sometimes called PITI — also includes property taxes, homeowners insurance, and PMI if your down payment is under 20%. A rough rule of thumb: add 1-2% of the home value per year to your P&I budget to cover the rest.

15-Year vs 30-Year — Which Is Cheaper?

The 30-year is cheaper per month. The 15-year is dramatically cheaper overall. On a $400,000 loan at 6.5%:

  • 30-year: $2,528/month, $510,000 total interest
  • 20-year: $2,983/month, $315,000 total interest
  • 15-year: $3,484/month, $227,000 total interest

The 15-year saves you $283,000 in interest vs the 30-year. The catch: $956 more per month. If you can afford the higher payment without sacrificing retirement contributions or emergency savings, the 15-year is the better deal. If not, the 30-year with extra principal payments when you can captures most of the benefit while preserving cash flow flexibility.

The Mortgage Formula

M = P × r × (1 + r)n / ((1 + r)n - 1)

Where:

  • M = Monthly payment (principal + interest)
  • P = Loan amount (principal)
  • r = Monthly interest rate (annual rate ÷ 12 ÷ 100)
  • n = Total number of payments (years × 12)

Example: $400,000 at 6.5% for 30 years: P = 400000, r = 0.005417, n = 360. M = approximately $2,528/month. Over 30 years you pay $910,162 total — $510,162 of which is interest.

Frequently Asked Questions

How is a mortgage payment calculated?
Mortgage payments use the amortization formula: M = P × r × (1+r)^n / ((1+r)^n - 1), where P is the loan amount, r is the monthly rate, and n is the total number of payments. The same payment is made every month, but the split between principal and interest changes over time.
What's the difference between a 15-year and 30-year mortgage?
A 15-year mortgage has roughly 38% higher monthly payments but cuts total interest by ~55% vs a 30-year. On a $400k loan at 6.5%, a 30-year costs $2,528/mo with $510k interest; a 15-year costs $3,484/mo with $227k interest. Total savings: ~$283,000.
Does this calculator include taxes and insurance?
No — this shows principal + interest (P&I) only. Property taxes typically add 1-2.5% of home value per year. Homeowners insurance adds $1,200-$2,500 annually. If your down payment is under 20%, PMI adds another 0.5-1.5%. Budget for the full PITI to avoid surprises.
How much does my credit score affect the rate?
Significantly. The gap between a 760+ credit score and a 620 score is often 0.75-1.5% in mortgage rate. On a $400k loan at 6.5% vs 7.5%, that's about $260 more per month and $94,000 more in total interest. Boosting your score by even 20-40 points before applying can pay off massively.
Should I pay points to lower the rate?
Each point costs 1% of the loan amount and typically lowers the rate by 0.25%. Break-even is usually 4-7 years. If you'll stay in the home longer than that, points save money. If you might refinance or sell sooner, skip them.

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