Personal Loan Calculator — Monthly Payment & Total Interest Before You Sign
Compare loan offers side by side and see which rate and term saves the most money
Reviewed for accuracy June 21, 2026 by Gary S.
22% of loan amount paid in interest — $3,248.75 over 5 years
At 8% APR, your $15,000.00 loan costs $3,248.75 in total interest. Extra payments compound in your favor — each dollar reduces balance and all future interest that balance would generate.
- ›Pay $100/month extra → 17 fewer months and $870.48 less interest
- ›Total interest ($3,248.75) is 22% of the original loan amount
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How to use Loan Calculator
Free loan calculator. Enter loan amount, annual interest rate, and term to instantly see your monthly payment, total interest paid, and total loan cost. Works for personal loans, home equity loans, and any fixed-rate loan.
A loan calculator lets you see your monthly payment, total interest, and total repayment cost before you accept a loan offer. Enter the loan amount, annual interest rate, and repayment term — the calculator applies the standard amortisation formula and shows your results instantly. Use it to compare loan offers side by side, test how a shorter term reduces total interest, or figure out the maximum loan amount your budget can support.
How to use this Loan Calculator
- 1Enter the loan amount — the total principal you plan to borrow, not including any origination fees.
- 2Enter the annual interest rate as a percentage. Find this in the loan offer under "APR" or "interest rate" — use the interest rate (not APR) for the formula.
- 3Enter the loan term in years. Common personal loan terms are 2, 3, 5, or 7 years.
- 4Read your monthly payment, total interest paid, and total amount repaid across the full term.
- 5Try multiple scenarios: shorten the term to see how much interest you save, or increase the amount to check if the payment stays affordable.
Monthly loan payment formula explained
All fixed-rate loans — personal, auto, student, home equity — use the same amortisation formula. Each payment covers the month's interest first; the remainder reduces the principal. Early payments are mostly interest; later payments are mostly principal.
| Variable | Meaning |
|---|---|
| M | Monthly payment |
| P | Principal (loan amount) |
| r | Monthly interest rate (annual rate ÷ 12) |
| n | Total number of payments (years × 12) |
Personal loan example: $15,000 at 9% over 5 years
- 01Loan amount: $15,000. Annual rate: 9% → monthly rate r = 0.09 ÷ 12 = 0.0075.
- 02Loan term: 5 years → n = 5 × 12 = 60 payments.
- 03Monthly payment = $15,000 × [0.0075 × (1.0075)^60] / [(1.0075)^60 − 1]
- 04(1.0075)^60 = 1.5657. Monthly payment = $15,000 × [0.0075 × 1.5657] / [1.5657 − 1]
- 05Monthly payment = $15,000 × 0.011743 / 0.5657 = $311.38
Result
Monthly payment: $311.38. Total paid over 5 years: $18,682.80. Total interest: $3,682.80.
What affects your monthly loan payment?
Interest rate
The rate determines how much of each payment goes to interest vs principal. A 12% personal loan vs 9% costs $24 more per month on a $15,000 loan — $1,440 more over 5 years. Always shop rates from banks, credit unions, and online lenders.
Loan term
Longer terms lower your monthly payment but dramatically increase total interest. A $15,000 loan at 9% costs $3,683 in interest over 5 years but $7,357 over 10 years — double the interest for half the payment reduction.
Loan amount
Only borrow what you need. Every extra $1,000 on a 5-year 9% loan adds $20.76/month and $245 in total interest. Origination fees (typically 1–8% of the loan amount) are usually deducted from the disbursement — factor these into your actual needs.
Credit score
Your credit score is the primary determinant of your interest rate offer. A 760+ score typically gets the best personal loan rates. Scores below 640 may face rates of 20–36% or outright denials. Check your score before applying.
Fixed vs variable rate
This calculator assumes a fixed rate — the rate and payment never change. Variable-rate loans start lower but can increase over time. Fixed rates are preferable for loans over 3 years where payment certainty matters.
Origination fees
Many personal loans charge origination fees of 1–8% of the loan amount, deducted from the disbursement. A $15,000 loan with a 3% fee disburses $14,550 but you repay $15,000. The APR captures this true cost — compare APRs, not just interest rates, when evaluating offers.
Tips and things to know
- ✓Compare APRs across lenders, not just interest rates. APR includes origination fees and gives the true cost of the loan.
- ✓Pre-qualifying with multiple lenders (typically a soft credit pull) lets you compare real rate offers without hurting your credit score.
- ✓Paying bi-weekly instead of monthly (26 half-payments vs 12 full payments per year) adds one full extra payment annually and saves meaningful interest on multi-year loans.
- ✓If you have high-interest credit card debt (20%+), a personal loan at 9–12% to consolidate it is almost always worth the origination fee.
- ✓Always check for prepayment penalties before taking a loan — some lenders charge a fee if you pay off early. Avoid these unless the rate is significantly lower.
Loan Calculator — bottom line
The most effective way to use this loan calculator is not to check whether you can afford a payment — it is to set a payment ceiling first and work backward to find the maximum loan amount and term that fit it. Decide what monthly payment your budget can absorb, enter it as your constraint, and then test how much principal that buys you at different terms and rates. This reverses the typical borrower's mistake of starting with "how much do I want to borrow" and hoping the payment is acceptable. The most common trap is extending the term to make a high loan amount feel affordable. Yes, a 7-year personal loan on $25,000 looks cheaper per month than a 3-year loan — but the total interest cost is often more than double. Run both term lengths here and look at the total interest column, not just the monthly payment. The difference is frequently $3,000–$5,000 or more. The second mistake is shopping rates only after you have already decided on a loan amount. Different lenders price the same loan amount and credit score very differently. A difference of 3 percentage points on a $20,000 loan over 5 years is roughly $1,600 in total interest. Pre-qualify with at least three lenders before committing. Practical action steps: (1) use this calculator to confirm that your target loan amount fits comfortably inside 10–15% of your gross annual income in total debt payments; (2) compare the total interest at your target term vs two years shorter; (3) if the loan is for debt consolidation, verify the total interest cost is less than continuing current minimum payments on the accounts you are consolidating — the Debt Payoff Calculator will show you those current payoff costs.
Official resources and further reading
Consumer Financial Protection Bureau — Personal Loans
The CFPB's official guide to personal loans — what to look for in loan terms, how APR works, and your rights as a borrower.
Federal Reserve — Consumer Credit Rates
The Federal Reserve's G.19 Consumer Credit report — benchmark interest rate data for personal and consumer loans updated monthly.
AnnualCreditReport.com — Free Credit Report
The only federally authorised source for free annual credit reports from all three major bureaus — check your score before applying for any loan.
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Frequently asked questions
The standard amortisation formula is: M = P × [r(1+r)^n] / [(1+r)^n − 1], where P is the principal, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments (years × 12). This formula ensures equal payments every month that fully repay the loan — plus all interest — by the final payment.
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