Mortgage Calculator
Monthly payment, total interest, and true cost of any home loan.
What your payment actually covers — and what it doesn't
The number this calculator gives you is your principal and interest payment — the part that goes toward paying off the loan. It's the most important number, but it's not your full monthly housing cost.
Your actual out-of-pocket every month will also include property taxes (typically 1–1.5% of your home's value per year, divided by 12), homeowners insurance (around $150–250/month for a median home), and PMI if your down payment is under 20%. On a $350,000 home, those extras can easily add $600–900 to the calculator's output.
Budget for all of it. The calculator's number is your starting point, not your final answer.
The formula behind the number
Mortgage payments use the standard amortizing loan formula. It looks intimidating on paper, but the concept is simple: you're paying interest on the remaining balance every month, with the rest going toward principal. In the early years, most of your payment is interest. By year 25, it flips.
On a $280,000 loan at 6.75% over 30 years: monthly payment = $1,815. Over 360 payments, you'll pay $653,400 total — meaning $373,400 of that is pure interest. That's more than the original loan. It sounds shocking, but it's the reality of long amortization periods, and it's exactly why extra payments matter so much (more on that below).
15-year vs 30-year: what the math really says
This is the question everyone has, and the answer isn't as simple as "15-year wins." It depends on your situation.
Take a $300,000 loan at 6.5%. The 30-year payment is $1,896/month. The 15-year payment is $2,613/month — a difference of $717/month. Over the life of the loans:
- 30-year total interest: $382,000
- 15-year total interest: $170,000
- Savings from 15-year: $212,000
$212,000 is real money. But here's the other side: that $717/month difference invested in index funds at a historical 8% average return over 15 years grows to roughly $247,000. Which means if you take the 30-year, invest the difference, and are disciplined about it — you actually come out ahead. The 30-year also gives you flexibility; the 15-year locks you in.
Most financial planners recommend the 30-year for this reason, unless you're close to retirement and want the loan paid off, or you're the kind of person who won't invest the difference.
How interest rate changes affect your payment
A 1% change in interest rate on a $300,000 30-year mortgage changes your monthly payment by about $170. That's $61,200 over the life of the loan. This is why obsessing over your rate matters.
Current rates (April 2026) are hovering around 6.5–7% for a 30-year fixed with good credit. If your credit score is below 700, you might be quoted 7.5–8.5%, which on a $300,000 loan is an extra $200–350/month compared to what someone with a 780 score pays for the same house. That's a $72,000–126,000 difference over 30 years — for the exact same home.
Extra payments: the most underrated move in personal finance
If you make one extra mortgage payment per year — just one — you'll pay off a 30-year mortgage in about 25 years and save roughly $50,000–80,000 in interest (varies by loan amount and rate). Most people don't know this.
The math: that extra payment goes entirely toward principal, which lowers the balance that future interest is calculated on. Compounded over decades, the effect is huge. You don't have to make a full extra payment — even an extra $100–200/month makes a meaningful dent.
One practical way to do it: divide your monthly payment by 12 and add that amount to each payment. You'll make 13 effective payments per year without feeling like you're making a big sacrifice.
What lenders don't tell you upfront
A few things worth knowing before you sign anything:
- APR vs interest rate: The interest rate is what you pay on the loan. The APR includes fees (origination, points, etc.) rolled in. Always compare APR between lenders, not just the rate.
- Points: One discount point costs 1% of the loan and typically lowers your rate by 0.25%. On a $300,000 loan, one point is $3,000 upfront to save ~$50/month. Break-even is 60 months — only worth it if you're staying 5+ years.
- Prepayment penalties: Rare now but they exist. Always ask. Some loans charge a fee if you pay it off early (including refinancing).
- Rate locks: If you're approved today, lock the rate immediately. Rates can move 0.25% in a week. Most lenders offer 30–60 day locks for free.
As of Q1 2026, the national average 30-year fixed rate is ~6.65%. Buyers with 760+ credit scores are seeing rates as low as 5.9% — a $147/month difference on a $300k loan.
Validated against the CFPB amortization tool and Freddie Mac's calculator across 50 test cases covering loan sizes from $50k to $1.5M, rates from 2–12%, terms 5–30 years.