Loan Calculator
Use this Loan Calculator to estimate your payment, total interest, and total loan cost for a standard installment loan (personal loan, consolidation, home improvement, and more). Enter your loan amount, APR, term, and payment frequency to see an amortization-based estimate of how your balance declines over time. If you plan to pay extra, toggle an extra payment amount to preview how that can shorten your payoff date and reduce interest. For vehicle-specific comparisons, you can also try our Car Loan Calculator. Explore more tools in our Finance Calculators hub.
Enter your loan details
Tip: Press Enter to calculate. All fields are optional except loan amount, APR, and term.
Results
Run the calculator to reveal a premium, loan-specific breakdown with visuals and copy/share tools.
How this Loan Calculator works (amortization formulas)
Most installment loans use an amortization schedule: each payment covers interest due for the period, then the remaining amount reduces principal. Over time, interest shrinks because it’s calculated on a smaller balance. This calculator uses the standard payment formula for a fixed-rate loan and then simulates payments in a safe amortization loop when extra payments and fees are included.
Base payment formula: Let P be the financed principal, APR the annual percentage rate, r the periodic interest rate, and N the total number of payments. The regular periodic payment (excluding recurring fees) is:
Payment = P × r / (1 − (1 + r)^(-N)). If APR = 0, we use Payment = P / N.
Frequency adjustments: We set r by dividing APR by the number of payments per year: monthly r = APR/12, bi-weekly r = APR/26, weekly r = APR/52.
We also estimate N from your term: monthly uses total months; bi-weekly uses round(years×26) (or round(months/12×26)); weekly uses round(years×52) (or round(months/12×52)).
This is a practical approximation for planning; your lender’s exact calendar may differ slightly.
Extra payments: When you add extra, we apply it according to your chosen frequency and run an amortization loop that reduces the principal faster. Because interest each period is based on the remaining balance, paying down principal earlier typically reduces total interest. If you want a retirement-plan-specific version, our 401k loan calculator uses similar ideas but with plan-focused assumptions.
Fees: An upfront fee can be counted in total cost and can optionally be rolled into principal (increasing P). A recurring monthly fee is added to totals; for weekly/bi-weekly schedules, we spread it across payments proportionally as monthlyFee × 12 / paymentsPerYear.
This keeps totals consistent while still showing an intuitive “payment including fees.”
Use cases for a Loan Calculator
A loan payment estimate is most useful when you’re comparing options or stress-testing your budget before you sign. Here are common ways people use a Loan Calculator:
- Personal loan planning: check whether a monthly payment fits comfortably with your current bills.
- Debt consolidation comparison: compare one new payment vs multiple existing balances and see total interest over the full term.
- Home improvement loan: estimate the payment for a remodel, roof repair, or renovation financed over several years.
- Medical expense financing: model a realistic payment frequency and see how extra payments may reduce interest.
- Small business equipment loan: compare weekly vs monthly payments to match cash flow and invoice cycles.
- Fee-sensitive offers: test the same APR with and without origination or monthly service fees to see the true cost difference.
Worked examples (loan payment + interest + payoff)
These examples show how the periodic rate (r), number of payments (N), and payment formula combine to produce a practical estimate.
Your lender may round differently or use exact calendar dates, but the logic here is the standard amortization approach.
Example 1: 0% APR promotional financing
Simple division because interest is zero.
Inputs: Loan amount $2,400; APR 0%; Term 12 months; Frequency Monthly; Extras $0; Fees $0.
Steps: N = 12. APR = 0 ⇒ Payment = P / N = 2400 / 12 = $200.
Results: Payment ≈ $200/month, total interest ≈ $0, total cost ≈ $2,400, payoff ≈ 12 payments from the start date.
Example 2: Standard personal loan (no extras)
Classic amortization: same payment each period, interest declines over time.
Inputs: Loan amount $15,000; APR 9.50%; Term 5 years; Frequency Monthly; Extras $0; Upfront fee $0; Monthly fee $0.
Steps: months = 5×12 = 60 so N = 60. r = 0.095/12 ≈ 0.0079167. Payment:
P × r / (1 − (1+r)^(-N)).
Results (approx.): Monthly payment around the low-to-mid $300s, total interest in the low-to-mid $4,000s, total cost around $19k+ over the term, payoff around 60 payments from the start date.
Example 3: Extra payments + fee rolled into the loan
Extra reduces principal faster; rolling in a fee increases the financed amount.
Inputs: Loan amount $20,000; Upfront payment $1,000; APR 11.25%; Term 48 months; Frequency Monthly; Extra $75 each payment; Upfront fee $250 (rolled in); Monthly fee $6.
Steps: Financed principal starts near P = 20,000 − 1,000 + 250 = 19,250.
N = 48. r = 0.1125/12. We compute the base payment with the formula, then run the amortization loop applying extra = $75 each payment (plus the fee allocation) until the balance reaches zero.
Results (approx.): Payment is higher due to extra and fees, but total interest is typically lower than the no-extra scenario, and payoff can be months earlier depending on the balance trajectory and rate.
Common mistakes to avoid
- Mixing APR with periodic rate: APR is annual; monthly loans use
APR/12(or/26,/52) for period interest. - Wrong term units: entering “60” but leaving the unit as years can wildly inflate
Nand distort payment estimates. - Ignoring fees: origination and monthly service fees can materially change total cost even if the APR looks attractive.
- Assuming extra payments don’t change payoff date: extra reduces the balance sooner, which usually shortens the schedule.
- Comparing different frequencies incorrectly: weekly vs monthly changes both
randN; you should compare total cost and payoff time, not just “payment size.” - Overlooking prepayment rules: some loans have prepayment penalties or minimum interest; use extras as a planning estimate, then verify the loan terms.
Quick tips for better loan decisions
- Compare APR + fees together: the “cheapest” APR isn’t always the lowest total cost once fees are included.
- Test a shorter term vs extra payment: sometimes a shorter term is similar to paying extra, but it commits you to a higher required payment.
- Keep a buffer in your budget: choose a payment that still works if other expenses rise.
- Use frequency intentionally: weekly/bi-weekly can align with paychecks, while monthly can match bill cycles.
- Use extras for flexibility: if your loan allows it, voluntary extra payments can reduce interest while letting you pause extras if needed.
- Double-check lender rounding: small differences can happen from rounding and exact calendar conventions—focus on big-picture affordability and total cost.
Loan Calculator FAQs
+What is a loan calculator and what does it estimate?
A loan calculator estimates how a fixed-rate installment loan behaves over time. Based on your loan amount (principal), APR, term, and payment frequency, it calculates a regular payment using amortization math and then estimates total interest and total cost. This page also models extra payments and common fees so you can see how paying more toward principal can reduce interest and shorten the payoff timeline. It’s best used for budgeting and comparing offers, not as a binding lender quote.
+How do you calculate the monthly (or periodic) payment?
We use the standard amortization formula: Payment = P × r / (1 − (1 + r)^(-N)), where P is financed principal, r is the periodic interest rate, and N is the number of payments. For monthly payments, r = APR/12 and N = total months. For bi-weekly and weekly, we use r = APR/26 or APR/52 and estimate N from your term. If APR is 0%, payment becomes P/N. This gives a consistent planning estimate across frequencies.
+What’s the difference between APR and interest per payment?
APR is an annualized rate, which means it describes interest over a full year. Your loan accrues interest per payment period, so we convert APR into a periodic rate by dividing by the number of payments per year (12 for monthly, 26 for bi-weekly, 52 for weekly). If you compare loans, always compare APR plus fees and the total cost over the term. For refinance-style comparisons, our auto loan refinance calculator approach can be a helpful cross-check.
+How do extra payments change the payoff date and total interest?
Extra payments reduce your principal faster. Because interest is calculated on the remaining balance each period, a smaller balance generally produces less interest over time. In this calculator, extras trigger an amortization loop that applies your extra amount on the schedule you selected (each payment, roughly monthly, or annually) and stops when the balance reaches zero. We then compare your “with extra” scenario to a no-extra baseline to show interest savings and time saved.
+How are fees handled in the results?
Upfront fees are added to total cost (if you keep fees included) and can optionally be rolled into the financed principal, which increases the balance and therefore interest. Recurring monthly fees are added as costs across the schedule; for monthly payments we add them each payment, and for weekly/bi-weekly we spread the monthly fee across payments proportionally so totals stay consistent. This makes it easier to compare offers where the APR is similar but fee structures differ.
+Why does weekly or bi-weekly payment math look different from monthly?
Payment frequency changes both the periodic rate and the number of payments. With weekly or bi-weekly, interest is applied more often at a smaller periodic rate (APR/52 or APR/26), and the term becomes more payments overall. The calculator uses a practical estimate of N based on your term length (years or months). That means your results are great for planning and comparisons, but lenders may compute exact payment dates using specific calendar conventions. Focus on total cost and payoff time, not only the payment size.
+What if my APR is 0% or my interest rate is very low?
If APR is 0%, the amortization formula would divide by zero, so we handle this safely by using simple division: Payment = Principal / Number of Payments. Total interest becomes $0, and the total cost is principal plus any fees you include. If APR is very small but not zero, the standard formula still works, but results can be sensitive to rounding. That’s why this tool keeps higher precision internally and then rounds display values using a consistent policy so you don’t see confusing “NaN” or unstable outputs.
+How accurate is the payoff date estimate?
The payoff date is an estimate based on your start date and the number of payments needed to reach a zero balance under your chosen payment frequency and extra payment plan. Monthly schedules add months; bi-weekly adds 14-day steps; weekly adds 7-day steps. Real loans may shift dates for weekends, holidays, or lender conventions, and some lenders apply extra payments in specific ways. Use the date as a planning reference, and if exact timing matters, confirm the lender’s payment calendar and rules.
+Can I use this for different loan types (personal, consolidation, etc.)?
Yes—this Loan Calculator is designed for general installment loans with a fixed interest rate and a regular payment structure. That includes many personal loans, debt consolidation loans, small business term loans, and common financing arrangements. If a loan has unusual rules (balloon payments, interest-only periods, variable rates, or prepayment penalties), your actual results can differ. In those cases, treat the output as a baseline estimate and consider specialized tools or the lender’s detailed disclosure to confirm exact costs.