Buying a home is likely the biggest financial decision you'll make. Yet most people spend more time researching their next phone than comparing mortgage options. The difference between a good and bad mortgage choice can cost you tens of thousands of dollars over the life of the loan — sometimes more than six figures.
The mortgage market offers dozens of loan types, each with trade-offs that depend on your income, savings, credit score, and how long you plan to stay in the home. Choosing blindly, or just going with whatever your real estate agent suggests, is a recipe for overpaying.
Here's a practical guide to picking the right mortgage.
How Mortgage Payments Actually Work
Before comparing loan types, you need to understand what you're paying for. A monthly mortgage payment has four components, commonly called PITI:
| Component | What It Covers | Typical % of Payment |
|---|---|---|
| Principal | Pays down your loan balance | 20-30% (early years) |
| Interest | Cost of borrowing the money | 50-70% (early years) |
| Taxes | Property taxes (escrowed) | 10-15% |
| Insurance | Homeowner's insurance (escrowed) | 3-5% |
The surprise for most first-time buyers: in the early years, most of your payment goes to interest, not principal. On a 30-year $400,000 loan at 7%, your first payment of $2,661 puts only $328 toward principal. The other $2,333 is pure interest. That ratio gradually flips over the life of the loan — a process called amortization.
This is why making extra principal payments early can save you enormous amounts of interest. Even an extra $200/month toward principal on that same loan would save you over $100,000 in total interest and shave nearly 7 years off the loan.
Use a Mortgage Calculator to see exactly how your payments break down between principal and interest at any point in the loan.
Fixed-Rate vs Adjustable-Rate Mortgages
This is the first and most important decision. Every other choice flows from it.
Fixed-rate mortgages
Your interest rate stays the same for the entire loan. If you lock in 6.5%, you pay 6.5% whether rates go to 4% or 10% next year.
Best for: - People planning to stay 7+ years - Anyone who values payment predictability - Buyers in low-rate environments (lock in before rates rise)
The trade-off: Fixed rates are typically 0.5-1% higher than the initial rate on adjustable mortgages. You pay a premium for certainty.
Adjustable-rate mortgages (ARMs)
The rate is fixed for an initial period (usually 5, 7, or 10 years), then adjusts periodically based on a market index. A "5/1 ARM" means fixed for 5 years, then adjusting once per year.
Best for: - People who plan to sell or refinance within 5-7 years - Buyers in high-rate environments expecting rates to drop - Those who need lower initial payments to qualify
The trade-off: After the fixed period, your rate (and payment) can increase significantly. Most ARMs have caps — for example, 2% per adjustment and 5% lifetime — but a 5% increase on a $400,000 loan adds over $1,000/month to your payment.
Which to choose?
Ask yourself one question: How long will I keep this loan? If the answer is less than the ARM's fixed period, the ARM usually wins. If longer, the fixed rate is safer.
| Scenario | Recommended | Why |
|---|---|---|
| First home, plan to upgrade in 5 years | 5/1 ARM | Lower rate during your ownership period |
| Forever home, staying 15+ years | 30-year fixed | Payment predictability for decades |
| High rates now, expect to refinance in 2-3 years | 7/1 ARM | Lower initial cost, refinance when rates drop |
| Conservative, hate financial surprises | 30-year fixed | Peace of mind is worth the premium |
15-Year vs 30-Year: The Term Decision
After choosing between fixed and adjustable, you pick your loan term. The two most common are 15 and 30 years.
30-year mortgage
Lower monthly payments, but you pay significantly more total interest. This is the most popular choice in the US — roughly 90% of purchase mortgages.
15-year mortgage
Higher monthly payments, but you build equity faster and pay far less total interest. Rates on 15-year loans are typically 0.5-0.75% lower than 30-year loans.
The math tells the real story
Let's compare a $350,000 loan:
| 30-Year at 7.0% | 15-Year at 6.5% | |
|---|---|---|
| Monthly payment (P&I) | $2,329 | $3,049 |
| Total interest paid | $488,281 | $198,858 |
| Interest savings | — | $289,423 |
| Monthly difference | — | +$720 |
The 15-year option saves you nearly $290,000 in interest. But it requires $720 more per month. Can you afford that? And should you?
Here's the nuanced take: if you'd invest that $720 difference and earn 8-10% in the stock market, you might come out ahead with the 30-year loan. But that requires discipline — you actually have to invest the difference, not spend it. For most people, the forced savings of a 15-year mortgage is more effective than the theoretical advantage of investing the difference.
Run your own numbers with a Mortgage Calculator to see the exact trade-off for your loan amount and rates.
How Much House Can You Actually Afford?
Lenders will approve you for more than you should spend. Their limits are based on what you can technically pay, not what leaves you financially comfortable.
The 28/36 rule
Most financial advisors recommend:
- 28% rule: Your total housing costs (PITI) should not exceed 28% of your gross monthly income.
- 36% rule: Your total debt payments (housing + car loans + student loans + credit cards) should not exceed 36% of gross monthly income.
Example: Gross income of $8,000/month. - Max housing payment: $8,000 x 0.28 = $2,240 - Max total debt payments: $8,000 x 0.36 = $2,880
If you have $400/month in other debt, your max housing payment drops to $2,480 under the 36% rule — but the 28% rule ($2,240) is more restrictive, so that's your real ceiling.
The down payment question
Conventional wisdom says 20% down. That's $70,000 on a $350,000 home — a barrier for many buyers. But you don't need 20% to buy a home:
| Down Payment | PMI Required? | Typical PMI Cost | Total Added Cost |
|---|---|---|---|
| 20%+ | No | $0 | $0 |
| 10-19% | Yes | $80-150/month | $960-1,800/year |
| 3.5% (FHA) | Yes | ~0.85% of loan/year | ~$2,975/year on $350K |
| 0% (VA/USDA) | No (but funding fee) | $0 | One-time fee |
PMI (Private Mortgage Insurance) protects the lender if you default. It typically costs 0.3-1.5% of your loan amount per year and drops off automatically once you reach 20% equity.
Putting less down isn't necessarily bad — if it means buying sooner and building equity instead of paying rent, the math often works out. But it does increase your monthly payment and total interest paid.
Interest Rates: What Determines Yours
Your interest rate depends on factors you control and factors you don't.
Factors you control
- Credit score: The single biggest factor. A 760+ score gets you the best rates. Every 20-point drop can add 0.125-0.25% to your rate.
- Down payment: More money down = lower rate. Lenders see less risk.
- Debt-to-income ratio: Lower is better. Pay down existing debt before applying.
- Loan type: Conventional loans often have lower rates than FHA for strong borrowers.
Factors you don't control
- Federal Reserve policy: The Fed doesn't set mortgage rates directly, but its actions heavily influence them.
- Bond market: Mortgage rates closely track the 10-year Treasury yield.
- Economic conditions: Inflation, employment data, and GDP growth all move rates.
How to get the best rate
Shop around. Seriously. The difference between lenders on the same day can be 0.5% or more. On a $400,000 loan, 0.5% costs you roughly $120/month or $43,000 over 30 years.
Get quotes from at least three lenders: a big bank, a credit union, and an online lender. Compare the Annual Percentage Rate (APR), not just the interest rate — APR includes fees and gives you the true cost of borrowing.
Common Mortgage Mistakes to Avoid
Skipping the pre-approval
A pre-approval letter tells sellers you're serious and tells you exactly what you can borrow. Without it, you're guessing at your budget and losing competitive offers.
Ignoring closing costs
Closing costs typically run 2-5% of the loan amount. On a $400,000 loan, that's $8,000-$20,000 due at closing. Budget for this separately from your down payment.
Choosing based on monthly payment alone
A longer loan term or interest-only period can lower your monthly payment while dramatically increasing your total cost. Always look at the total interest paid over the life of the loan.
Not considering refinancing as a strategy
If rates are high when you buy, getting an ARM or planning to refinance later can be smart. But don't count on rates dropping — have a plan that works even if rates stay flat.
Making major purchases before closing
Buying a car, opening new credit cards, or changing jobs between pre-approval and closing can derail your mortgage. Lenders re-check your finances right before closing. Keep everything stable.
The Mortgage Decision Checklist
Before signing, verify these items:
- Total monthly payment (PITI) is under 28% of gross income
- Total debt-to-income stays under 36%
- Emergency fund covers 3-6 months of the new payment after closing costs
- Rate type (fixed vs ARM) matches your time horizon
- Loan term balances monthly affordability with total interest cost
- You've compared at least 3 lenders on APR, not just interest rate
- Closing costs are budgeted separately from down payment
- You can still save for retirement and other goals after the mortgage payment
If any of these don't check out, you're either looking at too much house or need to adjust the loan structure. Run different scenarios through a Mortgage Calculator — try different down payments, terms, and rates until you find the combination that fits.
Frequently Asked Questions
How much should I put down on a house?
As much as you can without depleting your emergency fund or retirement savings. The 20% target eliminates PMI and gives you a lower rate, but many buyers successfully purchase with 3.5-10% down. Calculate the total cost difference — sometimes paying PMI for a few years costs less than waiting years to save 20%, especially if home prices are rising.
Is it better to get a 15-year or 30-year mortgage?
A 15-year mortgage saves you significantly on total interest and builds equity faster, but requires higher monthly payments. If the 15-year payment fits comfortably in your budget while leaving room for retirement savings and emergencies, it's the better financial choice. If it would stretch your budget too thin, take the 30-year and make extra principal payments when you can.
Should I pay points to lower my interest rate?
Mortgage points (each point costs 1% of the loan and lowers your rate by ~0.25%) make sense if you'll keep the loan long enough to break even. Divide the point cost by your monthly savings to find the break-even month. If you'll stay beyond that point, buying points saves money. Typical break-even is 4-7 years.
What credit score do I need for a mortgage?
Minimum scores are 580 for FHA loans and 620 for most conventional loans, but you won't get competitive rates below 700. The sweet spot is 740+, where you qualify for the best rates available. If your score is below 700, spending 6-12 months improving it before applying can save you thousands per year.
How do I compare mortgage offers from different lenders?
Focus on the APR (Annual Percentage Rate), which includes the interest rate plus fees and points — it's the true cost of borrowing. Also compare closing cost estimates line by line. A lender offering a lower rate but higher fees might actually cost more. Request a Loan Estimate from each lender and compare them side by side.