Use the 30 Year Fixed Mortgage Calculator below to estimate your monthly Principal and Interest (P&I) payments. This is the most common and stable form of home financing, providing a predictable payment schedule over three decades.
30 Year Fixed Mortgage Calculator
Estimated Monthly Payment (P&I)
$0.00Detailed Calculation Steps:
30 Year Fixed Mortgage Formula
The standard fixed-rate mortgage payment formula is:
$$M = P \frac{i(1 + i)^n}{(1 + i)^n – 1}$$Where:
- $M$ = Monthly payment (Principal and Interest)
- $P$ = Principal loan amount
- $i$ = Monthly interest rate (Annual Rate / 1200)
- $n$ = Total number of payments (Loan Term in Years × 12)
Formula Sources:
Wikipedia – Mortgage Calculator Investopedia – Mortgage Payment FormulaVariables Explained
The calculation relies on the following variables you input:
- Principal Loan Amount: The total amount of money borrowed from the lender.
- Annual Interest Rate (%): The yearly interest rate charged on the loan. This is divided by 12 to get the monthly rate used in the formula.
- Loan Term (30 Years): The fixed period over which the loan will be repaid, which is 360 monthly payments for this calculator.
What is a 30 Year Fixed Mortgage?
A 30-year fixed-rate mortgage is a home loan where the interest rate remains the same for the entire 30-year (360-month) term. This stability is the primary benefit, as the monthly Principal and Interest (P&I) payment will never change, regardless of economic fluctuations.
While the long term means you’ll pay more total interest compared to a 15-year loan, the lower monthly payments make homeownership more affordable and easier to budget for, especially for first-time buyers or those with other significant financial commitments.
How to Calculate a 30 Year Fixed Mortgage Payment (Example)
Let’s calculate the monthly payment for a $300,000 principal at a 6.0% annual interest rate:
- Convert the Annual Rate to Monthly Interest Rate ($i$): $i = 6.0\% / 1200 = 0.005$
- Determine the Total Number of Payments ($n$): $n = 30 \text{ years} \times 12 \text{ months/year} = 360$
- Calculate the Compounding Factor $((1 + i)^n)$ for 360 payments: $(1 + 0.005)^{360} \approx 6.022575$
- Apply the Monthly Payment Formula ($M$): $$M = \$300,000 \times \frac{0.005 \times 6.022575}{6.022575 – 1}$$
- Solve for $M$: $M \approx \$1,798.65$ (Monthly P&I Payment)
Related Calculators
- 15 Year Fixed Mortgage Calculator
- Loan Refinance Breakeven Calculator
- PITI Payment Estimator
- Amortization Schedule Generator
Frequently Asked Questions (FAQ)
What is the difference between P&I and PITI?
P&I stands for Principal and Interest—the core components of the loan. PITI stands for Principal, Interest, Taxes, and Insurance, which represents the full monthly housing cost, including escrowed property taxes and homeowners insurance. This calculator only estimates P&I.
Can I pay off a 30-year mortgage early?
Yes. Most 30-year fixed mortgages do not have prepayment penalties. Making extra principal payments can significantly reduce the total interest paid and shorten the loan term.
Is the interest rate truly fixed for 30 years?
Yes, for a fixed-rate mortgage, the interest rate you receive at closing is guaranteed and will not change for the entire 30-year duration of the loan.
What is the maximum debt-to-income (DTI) ratio for a mortgage?
While this varies by lender and loan type, most lenders prefer a maximum DTI ratio of 43% to 50% for qualified borrowers.