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avec graphiques et tableaux d'amortissement en temps réel.

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Comprehensive Mortgage Guide & Calculator Reference

How Mortgage Payments Work: The PITI Breakdown

When you take out a mortgage, your monthly payment is made up of four components — collectively known as PITI. Understanding each piece helps you see exactly where your money goes every month:

Principal: This is the portion that reduces the actual balance you owe. In the first years of a 30-year loan, only a small fraction of each payment touches principal. For example, on a $280,000 loan at 6.5%, your first monthly payment of $1,770 puts just $253 toward principal — the rest goes to interest.

Interest: The cost the lender charges for letting you use their money. Interest is calculated on the remaining balance, so it starts high and decreases over time as you pay down the loan. This is why making extra payments early can save you tens of thousands in interest.

Taxes municipaleses: Annual taxes set by your local government, usually between 0.5% and 2.5% of your home's assessed value. Most lenders collect 1/12th of the annual tax bill each month and hold it in an escrow account, then pay the tax authority directly when it's due.

Assurance habitation: Homeowners insurance protects your property against fire, storms, theft, and liability. Lenders require it because your home is their collateral. Like taxes, insurance premiums are typically escrowed — collected monthly and paid by the lender when the policy renews.

In the early years of a mortgage, the vast majority of each payment goes toward interest. Over time, as the principal balance decreases, a larger share of each payment goes toward paying down what you owe. This gradual shift is called amortization — and it's exactly what the chart above illustrates.

Amortization Formula
M = P × [ r(1+r)n ] / [ (1+r)n - 1 ]
Where:
• M = Total monthly principal & interest payment
• P = Principal loan amount (Home price minus down payment)
• r = Monthly interest rate (Annual rate / 12 months)
• n = Total number of payments (e.g., 360 payments for a 30-year loan)
💡 Pro Tip

Making just one extra payment per year on a 30-year mortgage can shave 4–5 years off your loan term and save you thousands in interest. Even rounding your payment up to the nearest $100 makes a meaningful difference over time.

The True Cost of a 30-Year Mortgage — A Worked Example

Mortgage math can be eye-opening. Let's walk through a realistic scenario to see how much a home actually costs over 30 years:

Scenario: You buy a $350,000 home with a 20% down payment ($70,000), borrowing $280,000 at 6.5% fixed for 30 years.

• Monthly P&I payment: $1,770

• Total of 360 payments: $637,200

• Total interest paid: $357,200 — that's more than the original loan amount!

• Add property tax ($375/mo) and insurance ($100/mo), and your actual monthly outlay is around $2,245.

This is why even small rate differences matter. Dropping from 6.5% to 6.0% on this same loan saves roughly $34,000 in total interest and lowers your monthly payment by about $95.

Taux fixe vs Taux variable

Choosing between a fixed-rate mortgage and an ARM depends on your plans, risk tolerance, and how long you expect to stay in the home. Here's how they compare:

FeatureFixed-Rate MortgageAdjustable-Rate (5/1 ARM)
Taux d'intérêt annuelLocked for the entire termFixed for 5 years, then adjusts annually
Typical Starting Rate6.5% (higher)5.75% (lower intro rate)
Payment PredictabilityFully predictableUncertain after intro period
Best ForLong-term homeowners (10+ years)Short-term stays or expected rate drops
Risk LevelLowModerate to High
Rate CapsN/ATypically 2% per adjustment, 5% lifetime cap

If you plan to sell or refinance within 5–7 years, an ARM's lower introductory rate could save you money. But if you're putting down roots, a fixed-rate mortgage provides peace of mind — your principal and interest payment never changes.

Mise de fonds Strategies & Private Mortgage Insurance (PMI)

Your down payment is the single biggest lever you control when purchasing a home. Here's what you need to know:

The 20% threshold: If you put down less than 20%, most conventional lenders will require Private Mortgage Insurance (PMI). PMI protects the lender (not you) if you default, and it typically costs between 0.5% and 1.5% of your loan amount per year. On a $280,000 loan, that's $1,400 to $4,200 per year — or $117 to $350 added to your monthly payment.

When does PMI go away? Under the Homeowners Protection Act, your lender must automatically cancel PMI once your loan-to-value ratio reaches 78%, and you can request cancellation at 80%. This gives you a strong incentive to build equity quickly through extra payments.

Low-down-payment options: FHA loans allow as little as 3.5% down. Some conventional programs allow 3%. VA loans and USDA loans offer 0% down for qualifying buyers. Each program has its own mortgage insurance rules, so compare total costs carefully. Visit HUD.gov for official guidance on government-backed loan programs.

15-Year vs. 30-Year Mortgage: Side-by-Side Comparison

Using our example of a $280,000 loan at 6.5% (30-year) vs. 6.0% (15-year — shorter terms typically earn lower rates):

Metric30-Year at 6.5%15-Year at 6.0%
Monthly P&I Payment$1,770$2,363
Total Payments (P&I)$637,200$425,340
Intérêts totaux Paid$357,200$145,340
Interest Savings—$211,860
Payoff Date (from 2025)20552040

The 15-year mortgage costs $593 more per month but saves you $211,860 in interest and has you mortgage-free 15 years sooner. If you can comfortably manage the higher payment, the 15-year term is financially superior.

How to Read Your Tableau d'amortissement

An amortization schedule is a month-by-month table that shows exactly how each payment is split between principal and interest, plus your remaining balance. Here's how to use it:

Early payments are interest-heavy. In month 1 of our $280,000 loan at 6.5%, $1,517 of the $1,770 payment goes to interest and only $253 to principal. By month 180 (halfway), the split is roughly 50/50. By the final year, nearly the entire payment goes to principal.

The "crossover point" is when your principal payment exceeds your interest payment for the first time. On a 30-year loan, this doesn't happen until roughly year 19–21, depending on your rate. Click "Afficher tous les paiements" above the calculator to see yours.

Use it for planning: Your amortization schedule shows how much equity you'll have at any point in the future — useful for refinancing decisions, PMI removal timing, or understanding your net worth.

5 Essential 5 conseils pour les premiers acheteurs

1. Get pre-approved before you shop

A pre-approval letter from a lender tells sellers you're serious and tells you exactly how much you can afford. It also locks in a rate for 60–90 days.

2. Budget for closing costs (2%–5% of the loan)

Beyond the down payment, expect to pay for appraisals, title insurance, origination fees, and prepaid taxes/insurance at closing. On a $280,000 loan, that's $5,600 to $14,000.

3. Compare at least 3 lenders

Rates and fees vary significantly between lenders. The CFPB's home-buying tools can help you compare Loan Estimates side by side.

4. Don't forget the hidden costs of ownership

Maintenance typically runs 1%–2% of your home's value per year. A $350,000 home may need $3,500–$7,000 annually for upkeep, repairs, and replacements.

5. Keep an emergency fund — don't drain savings for the down payment

Financial experts recommend keeping 3–6 months of expenses in reserve after closing. A broken furnace or job loss shouldn't put your new home at risk.

Foire aux questions (FAQ)

What is the 28/36 debt rule?
The 28/36 rule is a guideline lenders use to assess affordability. Your total housing expenses (PITI) should not exceed 28% of your gross monthly income, and your total debt payments — housing plus car loans, credit cards, and student loans — should not exceed 36%. For example, if you earn $7,000/month gross, your max PITI is $1,960 and your max total debt is $2,520.
How does my down payment affect my mortgage?
A larger down payment reduces your loan amount, which lowers both your monthly payment and total interest paid. On a $350,000 home, putting 20% down ($70,000) versus 10% ($35,000) saves roughly $320/month and over $80,000 in total interest on a 30-year loan at 6.5% — plus you avoid PMI entirely.
Should I choose a 15-year or 30-year term?
A 30-year term offers lower monthly payments, while a 15-year term saves enormous amounts on interest (see the comparison table above). Choose the 30-year if cash flow flexibility is important to you, but consider making extra payments to pay it off faster. Choose the 15-year if you can comfortably afford the higher payment.
What is Private Mortgage Insurance (PMI)?
PMI protects the lender — not you — if you default on a conventional loan with less than 20% down. It typically costs 0.5%–1.5% of the loan amount per year, added to your monthly payment. Once you reach 20% equity (80% loan-to-value), you can request its removal. At 78% LTV, the lender must remove it automatically.
What is an escrow account?
An escrow account is a neutral holding account managed by your mortgage servicer. Each month, a portion of your payment covers property taxes and homeowners insurance. The servicer holds these funds and pays the bills on your behalf when they're due — ensuring you never miss a tax or insurance payment.
Fixed-rate vs. adjustable-rate — which is better?
If you plan to stay in your home for 10+ years, a fixed-rate mortgage provides predictable payments and protection against rising rates. If you expect to move or refinance within 5–7 years, an ARM's lower introductory rate could save you money. Always consider the worst-case scenario: what happens when the ARM adjusts upward?
How do extra payments save me money?
Extra payments go directly toward reducing your principal. Since interest is charged on the remaining balance, every dollar of extra principal cuts future interest. Adding just $200/month to our $280,000 example saves over $98,000 in interest and pays off the loan almost 8 years early.
How do I read an amortization schedule?
Each row shows a single payment broken into principal, interest, and remaining balance. Early payments are interest-heavy; later payments are principal-heavy. The "crossover point" — where principal exceeds interest — typically occurs around year 19–21 on a 30-year loan. Use it to plan for PMI removal, refinancing, or tracking home equity growth.

Sources & Methodology

Data and calculations on this page are based on standard amortization formulas used by financial institutions. For current mortgage rates, visit the Federal Reserve. For guidance on mortgage shopping, see the CFPB's home-buying resources. For information on government-backed loan programs (FHA, VA, USDA), visit HUD.gov. This calculator is for educational purposes only — consult a licensed mortgage professional before making financial decisions.