Mortgage Rate Calculator
Find your monthly mortgage payment for any interest rate, or solve in reverse to find the exact rate you need to hit a target payment.
🏠 What is a Mortgage Rate Calculator?
A mortgage rate calculator answers the two most common questions home buyers ask: given a specific interest rate, what will my monthly payment be? And, given a monthly budget, what interest rate do I need to qualify for? Both questions are answered by the same underlying formula, the standard amortising loan payment equation, but solving for different variables. This calculator handles both directions in one tool.
The most practical use for the payment direction (Mode 1) is rate comparison shopping. Before committing to a lender, you can plug in the rates offered by multiple lenders and see the exact dollar difference in monthly payment and total interest cost. A 0.5% rate difference on a $350,000 loan over 30 years changes the monthly payment by roughly $115 and the lifetime interest cost by over $41,000. Seeing this in concrete numbers makes the value of negotiating or shopping multiple lenders immediately clear. The calculator also works for assessing how rate changes affect affordability: if rates rise from 6.5% to 7.5% while you are shopping for a home, you can instantly see how much your purchasing power decreases at your maximum monthly payment.
The rate-finder direction (Mode 2) is the less obvious but often more useful calculation. A buyer who knows they can afford exactly $1,800 per month on a $280,000 loan can use Mode 2 to find that they need a rate at or below approximately 6.8% for a 30-year term. That becomes a concrete target for negotiations. Without this calculation, most buyers either accept whatever rate they are offered or use rough rules of thumb that miss the actual constraint.
A common misconception is that the interest rate and APR are the same number. The interest rate is what this calculator uses: the base cost of borrowing before fees. APR is higher and includes lender fees in addition to the base rate. Always ask lenders for both figures when comparing offers. Another common error is ignoring the term selection: switching from 30 to 15 years at the same rate dramatically increases the monthly payment but cuts total interest paid roughly in half. This calculator includes 15-year, 20-year, and 30-year term options to make those comparisons straightforward.
📐 Formula
The formula is the standard fixed-rate amortisation equation used by all US lenders for conforming mortgages. Each monthly payment covers interest on the outstanding balance first, with the remainder reducing principal. Early payments are mostly interest; late payments are mostly principal. The total interest paid equals (monthly payment × number of payments) minus the original loan amount. Lenders are required to disclose the total interest cost in the Loan Estimate form under TILA-RESPA Integrated Disclosure rules.
📖 How to Use This Calculator
Steps
💡 Example Calculations
Example 1 - Standard 30-Year Purchase Mortgage
$350,000 loan at 7.25% for 30 years
Example 2 - Higher Rate, Shorter Term Comparison
$400,000 loan at 6.75% for 30 years vs 15 years
Example 3 - Jumbo Mortgage at Competitive Rate
$750,000 loan at 7.0% for 30 years
❓ Frequently Asked Questions
🔗 Related Calculators
What interest rate should I expect on a mortgage in 2025?
As of 2025, 30-year fixed mortgage rates in the US are in the 6 to 7.5 percent range depending on credit score, loan size, down payment, and lender. Borrowers with credit scores above 760 and at least 20% down typically qualify for the best available rates. Rates change weekly. Use this calculator to model any rate scenario before locking in.
How does mortgage interest rate affect monthly payment?
The monthly payment formula is M = P times r times (1+r) to the n, divided by (1+r) to the n minus 1. A higher rate increases both the numerator and denominator but the numerator grows faster, resulting in a higher payment. On a $300,000 loan at 30 years, each 1% increase in rate adds approximately $165 to $175 to the monthly payment and $59,000 to $63,000 in total interest.
What mortgage rate do I need to keep my payment under $2,000?
It depends on the loan amount and term. For a $300,000 loan at 30 years, you need a rate of approximately 7.6% or lower to stay at or under $2,000 per month. For $250,000 at 30 years, a rate of up to about 9.4% keeps the payment under $2,000. Use the Rate Finder mode (Mode 2) to find the exact rate for your specific loan amount, payment target, and term.
Is a 15-year or 30-year mortgage better?
A 15-year mortgage has a higher monthly payment (roughly 30 to 40% more) but saves substantial interest. On a $350,000 loan at 7%, the 30-year payment is about $2,329 and total interest is $488,000. The 15-year payment is about $3,146 and total interest is $216,000, a saving of $272,000. The 30-year is better if cash flow flexibility is critical; the 15-year wins on lifetime cost if you can afford the higher payment.
How do I calculate my mortgage payment manually?
Use the formula M = P times r times (1+r) to the n divided by (1+r) to the n minus 1. Where P = loan principal, r = monthly rate (annual rate divided by 12 divided by 100), n = total months (years times 12). For $300,000 at 7% for 30 years: r = 0.07/12 = 0.005833, n = 360, factor = (1.005833)^360 = 8.1164. M = 300,000 times 0.005833 times 8.1164 divided by 7.1164 = $1,995.91 per month.
What is the difference between interest rate and APR on a mortgage?
The interest rate is the cost of borrowing the principal, expressed as an annual percentage. APR (Annual Percentage Rate) includes the interest rate plus fees such as origination charges, discount points, mortgage broker fees, and certain closing costs. APR is always equal to or higher than the interest rate. Use APR when comparing loan offers from different lenders, as it reflects the true all-in cost. This calculator uses the stated interest rate, not APR.
How much does one discount point reduce my mortgage rate?
One discount point costs 1% of the loan amount and typically reduces the interest rate by 0.125% to 0.25%, though the exact reduction varies by lender and market conditions. On a $350,000 loan, one point costs $3,500 and at 0.25% reduction saves approximately $52 per month. The break-even period is roughly $3,500 divided by $52 = 67 months, just over 5.5 years. Points make sense if you plan to stay in the home beyond the break-even period.
Does my credit score affect the mortgage interest rate I get?
Yes, significantly. Lenders use risk-based pricing: borrowers with higher credit scores receive lower rates. The difference between a 620 FICO score and a 760 FICO score can be 0.5 to 1.5 percentage points on a mortgage rate. On a $350,000 loan at 30 years, a 1% rate difference means approximately $200 more per month and $72,000 more in total interest. Improving your credit score before applying can be one of the highest-return financial moves available.
How do I find the best mortgage rate?
Shop at least three to five lenders: major banks, regional banks, credit unions, and online lenders. All applications within a 45-day window count as a single credit inquiry for scoring purposes, so rate shopping does not hurt your credit score. Compare APR, not just the interest rate. Check for points, origination fees, and prepayment penalties. Get pre-approval in writing from each lender. The rate difference between the first quote and the best quote is often 0.25 to 0.5 percent or more.
What loan amount can I afford for a given monthly budget?
Use Mode 2 (Rate Finder) in reverse: enter a known rate and monthly budget to find the implied maximum loan. Alternatively, use the Home Affordability Calculator to factor in income, debt-to-income ratio, property tax, and insurance. A common rule of thumb is that your total housing payment (PITI) should not exceed 28 percent of gross monthly income. At $7,000 per month gross income, the 28% rule caps PITI at $1,960.
What is a fixed-rate vs. adjustable-rate mortgage?
A fixed-rate mortgage (FRM) keeps the same interest rate for the entire loan term, making monthly payments predictable. An adjustable-rate mortgage (ARM) starts at a lower introductory rate for an initial period (commonly 5, 7, or 10 years) then adjusts annually based on a market index plus a margin. ARMs carry rate risk after the initial period but may save money if you sell or refinance before the adjustment begins. This calculator models fixed-rate mortgages. For ARMs, use the initial rate to estimate early payments and a higher rate to stress-test future payments.