Loan Calculator
Calculate your loan payment amount, total interest, and generate a full amortization schedule. Supports monthly, bi-weekly, and weekly payment frequencies.
12 payments per year
Monthly Payment
$1,026
60 payments · Payoff: June 2031
Loan Amount
$50,000
Total Interest
$11,550
Total Repayment
$61,550
Interest / Loan
23.1%
How the Loan Calculator Works
This calculator uses the standard fixed-rate amortization formula to determine your periodic payment amount. Each payment is split between principal (reducing your balance) and interest (the cost of borrowing). Over time, the interest portion decreases while the principal portion increases — this is called amortization.
Loan Payment Formula
PMT = P × [r(1+r)ⁿ] / [(1+r)ⁿ - 1] PMT = Payment per period
P = Principal (loan amount)
r = Interest rate per period (annual rate ÷ periods per year ÷ 100)
n = Total number of payment periods (years × periods per year)
Example: Personal Loan Calculation
For a $50,000 personal loan at 8.5% interest for 5 years with monthly payments:
- r = 8.5% ÷ 12 ÷ 100 = 0.007083 per month
- n = 5 × 12 = 60 monthly payments
- PMT = $50,000 × [0.007083 × 1.007083⁶⁰] / [1.007083⁶⁰ - 1]
- Monthly Payment = $1,024
- Total Interest = $11,449 · Total Repayment = $61,449
Payment Frequency Comparison
Choosing a more frequent payment schedule (bi-weekly or weekly) can save you money. Here's a comparison for the same $50,000 loan at 8.5% for 5 years:
| Frequency | Payment | Total Interest | Savings |
|---|---|---|---|
| Monthly (12/yr) | $1,024 | $11,449 | — |
| Bi-weekly (26/yr) | $472 | $11,349 | $100 |
| Weekly (52/yr) | $236 | $11,298 | $151 |
Tips to Reduce Your Loan Cost
- Compare offers from multiple lenders — rates can differ 1-3%
- Improve your credit score before applying (740+ gets best rates)
- Choose the shortest term you can comfortably afford
- Switch to bi-weekly payments for automatic interest savings
- Make extra principal payments when possible — even $50/month helps
- Avoid prepayment penalties — read the fine print
- Consider refinancing if rates drop 1% or more below your current rate
Assumptions
- Interest rate does not change during the repayment schedule (no variable-rate adjustments)
- Equal monthly installments (standard EMI/amortization)
- No prepayments or extra payments made during the term
- No fees, closing costs, or origination charges included
- Interest compounds monthly on the outstanding balance
- Payments begin one month after loan origination
Limitations
- Does not account for variable or adjustable rate loans
- Processing fees, origination fees, and insurance not included
- Late payment penalties and grace periods not modeled
- Does not factor in tax deductibility of interest (e.g., student loans, mortgages)
- Balloon payments and interest-only periods not supported
- Real-world amortization may differ by 1-2 days due to day-count conventions
Common Mistakes
- Confusing APR with interest rate (APR includes fees; this calculator uses nominal rate)
- Not accounting for loan origination fees which effectively raise the rate
- Comparing loans with different terms without looking at total interest paid
- Ignoring the impact of bi-weekly payments (saves years of interest)
- Forgetting that longer terms mean lower payments but significantly more total interest
- Not considering prepayment penalties before making extra payments
References
- What Is Amortization? — Consumer Financial Protection Bureau
- Understanding Loan Costs — Federal Reserve Education
- APR vs Interest Rate — Consumer Financial Protection Bureau
Frequently Asked Questions
How is a loan payment calculated?
Loan payments are calculated using the standard amortization formula: PMT = P × [r(1+r)^n] / [(1+r)^n - 1], where P is the principal, r is the periodic interest rate, and n is the total number of payments. This ensures each payment is equal throughout the loan term, with early payments weighted toward interest and later payments toward principal.
What is the difference between monthly and bi-weekly payments?
With monthly payments, you make 12 payments per year. With bi-weekly payments, you pay every two weeks (26 payments/year), which equals 13 monthly payments annually instead of 12. This extra payment reduces the principal faster, saving significant interest over the loan life and shortening the payoff time by several years.
How does interest rate affect total loan cost?
Interest rate has a dramatic effect on total cost. For example, a $50,000 loan over 5 years at 5% costs $6,614 in interest. At 10%, it costs $13,748 — more than double. Even a 0.5% rate reduction on a large loan can save thousands of dollars.
Should I choose a shorter or longer loan term?
Shorter terms have higher payments but much less total interest. A 3-year term on $50,000 at 8% costs $5,411 in interest; a 7-year term costs $13,192. Choose shorter if you can afford the payments; longer if you need lower monthly obligations. Use this calculator to compare.
What is an amortization schedule?
An amortization schedule is a table showing every payment broken into principal and interest components. In the early years, most of each payment goes to interest. Over time, the interest portion shrinks and the principal portion grows. This calculator generates a year-by-year summary of this breakdown.
Does this calculator work for all loan types?
Yes, this calculator works for any fixed-rate installment loan: personal loans, auto loans, student loans, business loans, and fixed-rate mortgages. It does not apply to variable-rate loans, credit card balances, or interest-only loans, which use different repayment structures.
What factors affect my interest rate?
Key factors include: credit score (higher = lower rate), loan amount, loan term, collateral (secured vs unsecured), debt-to-income ratio, employment stability, and market conditions. Improving your credit score by even 50 points can reduce rates by 1-2%.