The Complete Guide to Mortgages
Everything you need to understand before taking out a mortgage: how much to put down, fixed vs variable rates, how amortization really works, the power of extra payments, PMI, closing costs, and when refinancing makes sense. A practical, numbers-first walkthrough for first-time and repeat home buyers alike.
Down payments: how much should you put down?
Your down payment is the cash you pay upfront toward the home price; the mortgage covers the rest. The traditional benchmark is 20% — on a $400,000 home, that means $80,000 down and a $320,000 loan. Putting 20% down usually gets you a lower interest rate, avoids mortgage insurance, and starts you off with meaningful equity.
But 20% is a guideline, not a law. Many buyers put down 5–10% (or as little as 3–3.5% with certain programs) and still come out fine. The trade-off is a bigger loan, a higher monthly payment, more total interest, and typically a mortgage insurance premium until you reach roughly 20% equity.
The real question is not "how much can I put down?" but "how much can I put down while keeping an emergency fund intact?" Draining every dollar of savings into a down payment leaves you exposed the first time the furnace dies or a job wobbles. A slightly smaller down payment with 3–6 months of expenses in reserve is usually the safer position.
Try the Mortgage Calculator →Fixed vs variable rates: which is right for you?
A fixed-rate mortgage locks your interest rate — and therefore your principal-and-interest payment — for the entire term. In the US, 30-year and 15-year fixed loans dominate. Fixed rates cost a bit more upfront than variable rates, but you are buying certainty: no matter what central banks do, your payment does not move.
A variable (adjustable) rate starts lower but resets periodically with market rates. In the US these are ARMs (e.g., a 5/1 ARM is fixed for five years, then adjusts annually). In Canada and the UK, shorter fixed terms of 2–5 years followed by renewal at prevailing rates are the norm, so most borrowers face rate resets even on "fixed" products.
Rule of thumb: choose fixed if a payment increase would strain your budget or you plan to stay long-term; consider variable only if you can comfortably absorb a payment that rises 20–30%, or you expect to sell or pay off the loan before the first reset. Never take a variable rate just to qualify for a bigger house — that is how borrowers get squeezed when rates climb.
Amortization explained: where your payment actually goes
Every mortgage payment is split between interest (the lender’s charge for that month) and principal (the part that reduces your balance). Early on, the split is heavily tilted toward interest because interest is calculated on the full outstanding balance. On a $320,000 loan at 6.5% over 30 years, roughly $1,733 of your first ~$2,023 payment is interest — only about $290 reduces the loan.
As the balance shrinks, less of each payment goes to interest and more to principal, and the shift accelerates over time. This schedule of payments is the amortization schedule, and reading yours is eye-opening: it shows the total interest over the life of the loan, which on a 30-year mortgage can approach or exceed the amount you borrowed.
Amortization is also why loan term matters so much. A 15-year loan carries a higher monthly payment but dramatically less total interest, because you spend fewer years paying interest on a large balance. Comparing a 15-, 20-, and 30-year schedule side by side is one of the most valuable exercises a borrower can do.
Try the Mortgage Calculator →Extra payments: the cheapest way to save tens of thousands
Because early payments are mostly interest, extra principal payments made early in the loan have an outsized effect. Every extra dollar goes 100% to principal, which means every future month’s interest is calculated on a smaller balance. The savings compound silently for decades.
A concrete example: on a $320,000, 30-year loan at 6.5%, adding just $200 per month cuts roughly five to six years off the loan and saves on the order of $70,000–$80,000 in interest. Even one extra full payment per year (easily done by paying half your payment every two weeks) shortens a 30-year loan by several years.
Before overpaying the mortgage, check two things: that your lender applies extra payments to principal (not to prepaying next month), and that there is no prepayment penalty. Also weigh the alternative — if your mortgage rate is 4% and you have not maxed tax-advantaged retirement accounts, investing the extra cash may beat prepaying. At 7%+, prepaying is a strong guaranteed return.
PMI and mortgage insurance: what it is and how to get rid of it
If you put down less than 20% on a conventional US loan, lenders typically require Private Mortgage Insurance (PMI). PMI protects the lender — not you — against default, and usually costs about 0.3%–1.5% of the loan amount per year, added to your monthly payment. On a $350,000 loan, that can be $90–$400 a month.
The good news: PMI is temporary. You can request cancellation once your balance falls to 80% of the home’s original value, and lenders must automatically remove it at 78%. Rising home values can get you there faster — an appraisal showing 20%+ equity can justify early removal. FHA loans work differently: their mortgage insurance premium often lasts the life of the loan unless you refinance into a conventional loan.
Do not let PMI alone scare you out of buying. If waiting three more years to save 20% means paying rising rents and rising home prices, a smaller down payment with temporary PMI can be the cheaper path. Run both scenarios with real numbers instead of guessing.
Closing costs: the bill nobody budgets for
Closing costs are the fees due when the purchase completes, and they routinely surprise first-time buyers. Expect roughly 2%–5% of the purchase price: lender origination fees, appraisal, title insurance and search, legal/escrow fees, government recording taxes, and prepaid items like property tax and homeowners insurance escrows. On a $400,000 home, that is $8,000–$20,000 on top of your down payment.
You can reduce closing costs by shopping lenders (origination and processing fees vary widely), asking the seller for concessions in a soft market, and comparing title insurance providers where allowed. Some lenders offer "no-closing-cost" loans that roll the fees into a higher rate — fine if you will sell or refinance soon, expensive if you keep the loan for decades.
Budget for closing costs and moving costs from the start. A buyer with exactly $80,000 saved does not have a 20% down payment on a $400,000 house — they have roughly a 16–17% down payment plus closing costs. Knowing this early prevents scrambling or draining emergency funds at the finish line.
Refinancing: when it makes sense (and when it doesn’t)
Refinancing replaces your current mortgage with a new one — ideally at a lower rate, a different term, or to pull out equity. The classic trigger is a rate drop: the old rule said refinance when rates fall 1% below yours, but the real test is the break-even point. Divide the refinance closing costs by your monthly savings; if you will stay in the home longer than that number of months, refinancing wins.
Example: $6,000 in refinance costs and a $250/month payment reduction means a 24-month break-even. Stay five more years and you net roughly $9,000. Move in 18 months and you lose money. Also watch the term reset trap: refinancing 25 years remaining into a fresh 30-year loan lowers the payment but can increase total interest — consider matching the remaining term instead.
Cash-out refinancing (borrowing more than you owe and pocketing the difference) can be sensible for high-interest debt consolidation or renovations that add value, but it converts unsecured problems into debt secured by your home. Treat it as a serious decision, not an ATM.
Rent vs buy: the decision before the mortgage
Before optimizing a mortgage, confirm buying is the right move at all. Buying wins when you stay put long enough for equity growth and appreciation to overcome the heavy transaction costs (buying and selling a home can consume 8–10% of its value combined). Renting wins when you may move within a few years, when price-to-rent ratios in your city are extreme, or when investing the difference would earn more.
A fair comparison counts everything: ownership costs include mortgage interest, property tax, insurance, maintenance (budget ~1% of home value per year), and forgone investment returns on the down payment. Renting costs include rent and annual rent increases — but frees up capital to invest. The break-even horizon in many markets lands around 4–7 years, though it varies enormously by city.
Run your own numbers rather than relying on folk wisdom like "rent is throwing money away." Interest, tax, insurance, and maintenance are also money you never get back — the honest comparison is total unrecoverable costs on each side, over your realistic time horizon.
Try the Rent vs Buy Calculator →Tools used in this guide
A mortgage calculator computes your estimated monthly mortgage payment based on home price, down payment, interest rate, and loan term. It also generates a full amortization schedule showing how each payment splits between principal and interest over the life of the loan.
The rent vs buy calculator helps you decide whether renting or buying a home makes more financial sense in your situation. It accounts for mortgage payments, property taxes, maintenance, home appreciation, rent increases, and the opportunity cost of a down payment to find your break-even point.