loan calculator

Payment Calculator

The Payment Calculator has two fixed-rate modes. Calculate Monthly Payment solves the equal monthly payment from loan amount, term years and months, and annual interest rate. Calculate Loan Term keeps the entered monthly payment and simulates how many whole months it takes to repay the balance, including total payments, total interest, payoff years, and a payment note.

Result

Solved value: Monthly payment = $1,687.71
Monthly payment: $1,687.71
Payoff months: 180
Payoff years: 15
Total payments: $303,788.46
Total interest: $103,788.46
What this means: Fixed-term estimate using equal monthly payments.

Scenario nameNotes

Save this result, then use saved scenarios to switch between assumptions.

How the Payment Calculator works

Use this calculator when you want to compare a fixed-term payment estimate with a fixed-payment payoff-time estimate using the same loan amount and entered rate. Use Loan Payment for the simpler amount-rate-years view, Amortization when you need a payment schedule, Interest Rate when the payment is known and the rate is unknown, APR when fees need a cash-flow-rate estimate, Credit Card Payoff for revolving-card payoff assumptions, and CFPB, Regulation Z, lender disclosures, or relevant local sources for real APR, Truth in Lending, approval, product, fee, tax, legal, or jurisdiction-specific questions.

The app rounds the payment count with termYears * 12 + termMonths and converts the entered Annual interest rate to a monthly decimal rate with annualRate / 100 / 12. In monthlyPayment mode, it solves PMT = P * m / (1 - (1 + m)^-n), where P is loan amount, m is monthly rate, and n is payment count; at 0 percent, PMT = P / n. Total payments equal the solved monthly payment times payment count, and total interest equals total payments minus loan amount. In loanTerm mode, the app first checks whether monthlyPayment is greater than first-month interest. If it is not, payoff fields return 0 with a warning note. Otherwise the helper simulates each month, adds interest, pays min(monthlyPayment, balance + interest), allows a reduced final payment, counts payoff months, sums total payments and total interest, and stops at a 12000-month safety cap.

Payment Calculator formula

This formula page covers the app's Payment Calculator: a two-mode fixed-rate payment solver. Fixed-term mode solves the monthly payment from loan amount, annual rate, and term years plus months. Fixed-payment mode keeps the entered monthly payment and simulates payoff time, total payments, and total interest. It does not calculate statutory APR, lender disclosures, product approval, amortization schedules, credit-card statement rules, annuity income, taxes, fees, escrow, variable rates, or personalised borrowing advice.

N = round(12Y + M); m = R / 100 / 12; fixed term: PMT = P * m / (1 - (1 + m)^-N); zero rate: PMT = P / N; fixed payment: I_t = B_(t-1) * m; Pay_t = min(PMT, B_(t-1) + I_t); B_t = B_(t-1) + I_t - Pay_t; TP = sum(Pay_t); TI = sum(I_t)

The calculator either solves a level monthly payment for a selected number of months or keeps the monthly payment entered by the user and runs a month-by-month payoff simulation with a reduced final payment when needed.

Symbol	Meaning	How this page uses it
P	Loan amount	The starting balance entered as Loan amount. The calculator treats it as the principal balance before fees, taxes, insurance, or lender-specific adjustments.
R	Annual rate percent	The Interest rate field. The formula converts it into a monthly note-rate assumption; it is not automatically an APR.
Y	Term years	The Loan term years input used when fixed-term mode solves the payment.
M	Term months	The Loan term months input. The app supports extra months even though independent comparator fixtures use whole-year terms.
N	Payment count	The rounded number of monthly payments: term years times 12 plus term months.
m	Monthly rate	The entered annual rate divided by 100 and then by 12.
PMT	Monthly payment	The solved monthly payment in fixed-term mode, or the entered monthly payment in fixed-payment mode.
B_t	Balance after month t	The remaining balance after adding that month's interest and subtracting that month's capped payment.
I_t	Monthly interest	The previous balance multiplied by the monthly rate.
Pay_t	Actual payment in month t	The smaller of the regular monthly payment and the balance plus current-month interest, so the final payment can be reduced.
TP	Total payments	The sum of monthly payments made by the selected solve mode.
TI	Total interest	The sum of monthly interest added during the calculation.

Step by step

Read the selected mode. In fixed-term mode, the unknown is the monthly payment. In fixed-payment mode, the unknown is payoff time.
Convert term years and term months into a rounded monthly payment count with N = round(12Y + M).
Convert the entered annual interest-rate percent into the app's monthly rate assumption with m = R / 100 / 12.
For fixed-term mode, use the standard fixed-payment formula PMT = P times m divided by 1 minus (1 + m) raised to negative N.
If the monthly rate is 0 in fixed-term mode, divide loan amount by payment count instead of using the interest formula.
Calculate fixed-term total payments as the solved monthly payment times N, then subtract loan amount to estimate total interest.
For fixed-payment mode, first compare the entered monthly payment with first-month interest. If the payment is not greater than first-month interest, the app reports zero payoff fields and a warning note instead of projecting an endless balance.
If the fixed payment can reduce principal, simulate one month at a time: add monthly interest, cap the payment at balance plus interest, subtract the payment, and continue until the balance is effectively zero.
In fixed-payment mode, count whole payoff months and use a reduced final payment when the remaining balance plus final interest is smaller than the regular monthly payment.
The payoff loop has a 12000-month safety cap. Treat any result near that boundary as an input problem rather than a practical payoff plan.
Use CFPB, Regulation Z, lender disclosures, or local regulator sources before turning this generic math into APR, Truth in Lending, payment-schedule, total-of-payments, product, legal, or jurisdiction-specific claims.

Worked example

Default examples: fixed term and fixed payment

The default inputs use a $200,000 loan amount, a 6 percent annual rate, a 15-year fixed term, and a $2,000 monthly payment for fixed-payment mode.

For fixed-term mode, convert 6 percent to a decimal annual rate of 0.06.
Divide 0.06 by 12 to get a monthly rate of 0.005.
Convert 15 years and 0 months into 180 monthly payments.
Apply PMT = P * m / (1 - (1 + m)^-N) with P = $200,000, m = 0.005, and N = 180.
The calculator reports a fixed-term monthly payment of $1,687.71.
Total payments are reported as $303,788.46, and total interest is $103,788.46.
For fixed-payment mode, keep the $2,000 monthly payment and simulate month by month at the same 0.005 monthly rate.
The $2,000 payment is larger than the first month's $1,000 interest, so the balance can amortize under this model.
The app reports a 139-month payoff, or 11.58 years after rounding the displayed payoff years.
Because the final payment can be reduced, total payments are reported as $277,951.56 and total interest as $77,951.56.

Fixed-term mode answers what payment fits a chosen term. Fixed-payment mode answers how long a chosen payment may take. Both are mechanical estimates from entered assumptions, not lender quotes or regulated disclosures.

Assumptions and what this calculator ignores

Geographic scope: works globally. The math is currency-agnostic, so enter amounts in your own currency; local taxes, fees, and product rules are not included.

The calculator models one fixed-rate monthly-payment scenario. It does not model variable rates, daily interest accrual, non-monthly schedules, skipped payments, extra payments, payment holidays, refinancing, late fees, balloon payments, escrow, taxes, insurance, lender credits, or product-specific contract rules.
The entered annual rate is the rate assumption used in the payment formula. It is not automatically a lender APR, legal disclosure rate, finance-charge classification, amount-financed disclosure, total-of-payments disclosure, or product comparison. A positive term is needed for fixed-term mode to be meaningful, and the fixed-payment mode reports whole payoff months with a smaller final payment when needed.
Scoped independent comparator checks pass 4 of 4 scoped fixtures for overlapping fixed-term payment, zero-rate payment, fixed-payment payoff time, total payments, and total interest outputs. CFPB APR guidance is needed before explaining entered rate versus lender APR; Regulation Z sections 1026.18 and 1026.22 plus APR table materials are needed before legal payment-schedule, total-of-payments, finance-charge, APR-determination, disclosure-accuracy, or Truth in Lending claims; and lender, FTC, state, local, Investor.gov, IRS, SEC, FCA, MoneyHelper, or product sources are needed before mortgage, auto-loan, student-loan, credit-card, annuity, pension, tax, legal, jurisdiction-specific, approval, underwriting, or regulated-product claims. Results are educational estimates, not financial, tax, legal, lending, credit, retirement-income, consumer-rights, regulatory, or personalised advice.

What this formula does not include

The calculator assumes a fixed annual rate converted to a simple monthly rate. It does not expose daily, weekly, annual, or custom compounding frequencies.
Fixed-term mode uses term years plus term months, rounded into a monthly payment count. A zero-month term is not a meaningful planning result.
Fixed-payment mode simulates whole months and allows a reduced final payment. Comparator tools can show fractional payment counts or fractional final-period totals.
If the entered fixed payment is less than or equal to first-month interest, the app reports zero payoff fields with a warning note. That branch means the inputs do not amortize under this simple model.
The payoff simulation stops at 12000 months as a safety cap. Extremely long results should be treated as a signal to recheck the inputs.
No fees, broker charges, discount points, closing costs, origination charges, insurance, escrow, taxes, late fees, prepayment penalties, payment holidays, credit insurance, statement allocation rules, or lender servicing rules are included.
The annual rate input is not automatically an APR. APR, finance charge, amount financed, payment schedule, total of payments, Truth in Lending, and jurisdiction-specific disclosure claims need CFPB, Regulation Z, lender, or local regulatory source checks.
The page is not an amortization schedule. Use the amortization calculator when month-by-month principal, interest, balance, and extra-payment assumptions matter.
The page is not an annuity, pension, retirement-income, credit-card minimum-payment, mortgage escrow, auto-loan, or personal-loan product calculator.
Scoped independent comparator checks currently pass 4 of 4 scoped fixtures for whole-year fixed-term payment solves plus one fixed-payment payoff-time scenario.
In fixed-payment validation, the independent comparator can report fractional payment counts and totals; this app rounds payoff to a whole month and models a reduced final monthly payment, so validation compares payoff years rather than fixed-payment total paid and interest.
The result is an educational estimate from the entered assumptions, not financial, tax, legal, lending, credit, mortgage, consumer-rights, retirement-income, or personalised advice.

Common mistakes to avoid

Using the monthlyPayment field in the fixed-term mode as if it controls the result. In Calculate Monthly Payment mode, that field can be present in the form but the solved payment is driven by loan amount, term, and annual rate.
Setting a fixed monthly payment too low to reduce the balance. If the entered payment does not exceed first-month interest, the calculator returns zero payoff fields and a warning note instead of pretending the loan amortizes.
Reading this page as a lender quote, legal APR, full amortization schedule, mortgage payment, credit-card statement calculation, annuity-income result, tax answer, product approval, or borrowing recommendation. Those questions need product documents, official sources, or qualified advice outside this calculator.

Key terms

Calculate mode: The selector that chooses whether the app solves the monthly payment or the payoff term. Monthly-payment mode uses the entered term; loan-term mode uses the entered monthly payment.
First-month interest: The starting balance multiplied by the monthly rate. In fixed-payment mode, the payment must exceed this amount before the balance can shrink.
Reduced final payment: The smaller last payment used when the remaining balance plus interest is below the regular payment. This is why total payments can be lower than monthly payment times payoff months in fixed-payment mode.

Frequently asked questions

What can I solve with this payment calculator's two modes?

Fixed-term mode answers 'what monthly payment clears this loan in this time' - the classic amortization solve. Fixed-payment mode inverts it: keep the payment you can actually afford ($2,000 in the default example against a $200,000 loan) and simulate how long payoff takes and what interest accrues. The second mode is the honest way to test a budget-first repayment plan.

What if my chosen payment barely covers the interest?

At 6 percent on $200,000, the first month's interest is $1,000 - a payment at or below that level never reduces the balance, and the simulation will show payoff time stretching toward its cap instead of converging. Even slightly above the threshold, payoff takes decades. The month-by-month simulation makes this cliff explicit, which is exactly the danger zone rule-of-thumb calculations hide.

Why does my final loan payment come out smaller?

Because the simulation pays exact balances, not rounded schedules. In fixed-payment mode each month adds interest, subtracts your payment, and the last month only needs whatever balance remains - so the final payment is min(payment, remaining balance plus interest). Real lenders handle final-payment rounding by contract and posting date, which is why a servicer's payoff figure can differ by a few dollars.

Methodology, sources, and disclaimer

This calculator is an original two-mode payment solver: fixed-term mode solves the level payment and fixed-payment mode simulates payoff month by month with a reduced final payment, validated by deterministic fixtures, edge cases, and rounding policy tests. It is not copied from a single source.

Fixtures pin both modes, the zero-rate branch, and the non-converging too-small-payment case. The result remains an educational estimate, not a lender schedule or a payoff quote.

Formula version 2026.05.22-generic-payment-term-solver. The version marks the calculation logic and validation fixture set used for this estimate.

CFPB APR versus interest-rate guidance should be used when copy explains the difference between the entered payment interest rate and a lender APR.
CFPB Regulation Z sections 1026.18 and 1026.22 plus APR table materials should be used when copy discusses finance charges, amount financed, payment schedule, total of payments, APR determination, disclosure accuracy, or Truth in Lending terminology.
Investor.gov, IRS, SEC, FCA, MoneyHelper, lender disclosures, or relevant local regulator sources should be used before copy frames the generic payment math as annuity income, pension income, mortgage, credit-card, auto-loan, product-specific, tax, legal, or jurisdiction-specific guidance.

Results are educational estimates, not advice. Read the full disclaimer.

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