Simple Loan Calculator
Estimate monthly payment, total interest, and total repayment for a basic loan.
Use this Simple Loan Calculator to estimate the monthly payment, total interest, total repayment, and payoff time for a basic fixed-rate installment loan. You can also include fees added to the loan and an optional extra monthly payment.
Important: This calculator estimates a standard amortizing loan. Actual lender payments and borrowing costs can differ because of fees, payment timing, interest methods, and specific loan terms.
Simple Loan Calculation Method
If fees are financed as part of the loan:
Amount financed = loan amount + financed fees
The annual interest rate is converted to a monthly rate:
Monthly rate = annual interest rate ÷ 12 ÷ 100
For a fixed-rate amortizing loan:
M = P × [r(1 + r)n] ÷ [(1 + r)n − 1]
Where:
- M = monthly payment
- P = amount financed
- r = monthly interest rate
- n = total number of monthly payments
If the interest rate is 0%:
Monthly payment = amount financed ÷ number of months
Total Interest and Repayment
Without extra payments:
Total repayment = monthly payment × number of payments
Total interest = total repayment − amount financed
When an extra monthly payment is entered, the calculator estimates the loan month by month because the additional principal payment can shorten the payoff period.
Worked Example
Suppose you borrow $10,000 at a fixed annual interest rate of 7.5% for 5 years, with no financed fees.
Loan term:
5 × 12 = 60 months
Monthly interest rate:
7.5% ÷ 12 = 0.625% per month
Using the amortization formula:
Estimated monthly payment ≈ $200.38
Estimated total repayment:
≈ $12,022.77
Estimated total interest:
$12,022.77 − $10,000 ≈ $2,022.77
So, under these assumptions, the $10,000 loan costs approximately $2,022.77 in interest over five years.
Financed Fees
If a lender adds an origination or processing fee to the loan balance, that fee increases the amount being financed.
For example, a $10,000 loan with a $250 financed fee uses:
Amount financed = $10,000 + $250 = $10,250
Because interest is then calculated on the larger financed balance, both the monthly payment and total interest can increase.
Important Notes
- This calculator is intended for fixed-rate loans with regular monthly payments.
- The interest-rate field should use the loan interest rate rather than treating lender APR as automatically equivalent.
- APR can include certain fees and other finance charges and is useful when comparing official loan offers.
- Fees entered in the calculator are assumed to be financed into the loan. Fees paid separately should not be added to the financed balance.
- A longer loan term generally reduces the monthly payment but can increase total interest.
- Extra-payment estimates assume the additional amount is applied toward principal. Confirm how your lender applies payments above the required amount.
- Prepayment penalties or other restrictions can reduce the benefit of paying a loan off early.
- Variable-rate loans, balloon payments, interest-only periods, deferments, skipped payments, taxes, insurance, and late fees are not modeled.
- The currency selector changes the displayed symbol only and does not convert exchange rates.
- Use the lender’s official disclosures when comparing actual loan offers.
How to Use the Simple Loan Calculator
Start with one clearly defined scenario and collect the values the calculator requests: principal, simple annual rate, time, and payment frequency. Use figures from current statements, quotes, pay records, contracts, or official documents whenever possible. Keep every rate and time period on the same basis before calculating. If one value is uncertain, enter a realistic estimate and then test a lower and higher alternative instead of treating a single forecast as certain.
Enter the values carefully, check the units, and calculate. The main results are simple interest, total repayment, and periodic payment. Save the assumptions alongside the result so you can reproduce the calculation later. For comparisons, change only one major input at a time. That makes it easier to see which variable is responsible for the difference and reduces the chance of comparing scenarios built on inconsistent assumptions.
How to Interpret the Results
This calculator is designed to calculate interest only on the original principal for the stated time. The result is an estimate based on the values supplied, not a quote, approval, tax ruling, investment recommendation, or contractual promise. Read the output together with its assumptions and compare the total cost or benefit—not only the most attractive headline number. A result that looks better in the short term may be less suitable when fees, timing, risk, or long-term obligations are included.
For a useful sensitivity check, recalculate with a less favorable rate, a different term, a larger cost, or a smaller income or return. Note the point at which the decision changes. This break point often provides more practical insight than a single best-case result because it shows how much uncertainty the plan can absorb.
Scenario Checklist
Before acting, confirm the source and date of every input; distinguish percentages from decimal values; include relevant fees and recurring costs; align monthly and annual figures; and verify whether values are before or after tax. Also consider inflation, opportunity cost, liquidity, and risk where relevant. Document the scenario name and calculation date so later comparisons use the same basis.
Important limitation: many consumer loans amortize or compound instead, and fees or irregular payments may change the true cost. Rules, market conditions, provider terms, and personal circumstances can change. Verify material decisions with the appropriate lender, employer, tax authority, regulator, financial professional, or contract documentation.
Related Finance Calculators
Continue your comparison with the Car Finance Calculator and Sales Tax Calculator. Using related calculators can reveal costs or assumptions that a single result does not capture.
Frequently Asked Questions
What does the Simple Loan Calculator calculate?
It uses principal, simple annual rate, time, and payment frequency to estimate simple interest, total repayment, and periodic payment. The exact fields and displayed results depend on the values entered and the calculator formula.
Which inputs have the biggest effect on the result?
The inputs with the greatest effect are usually the largest balances, prices, rates, time periods, payments, or recurring amounts. Change one of these at a time and compare the results to identify the most sensitive variable.
How accurate is the Simple Loan Calculator?
It is mathematically accurate for the supplied inputs and stated assumptions. Real-world accuracy depends on the quality of those inputs and whether all relevant fees, taxes, timing rules, rate changes, and personal circumstances are represented.
How should I compare different scenarios?
Create a realistic base case, then a conservative case and an optimistic case. Keep units and timing consistent, alter one important assumption at a time, and compare total outcomes as well as periodic amounts.
Does the calculator include every tax, fee, and rule?
No general calculator can capture every jurisdiction, provider term, exemption, fee, or future change. Include additional costs where fields allow and confirm the final figures with current official documents or the relevant provider.
Can I use this result for an official financial decision?
Use it for education, planning, and initial comparison. Before signing, filing, investing, borrowing, or making another material commitment, confirm the assumptions and final numbers with authoritative documents and an appropriately qualified professional.