Formula
Loan payment formula
Monthly payment = principal x monthly rate / (1 - (1 + monthly rate)^-months)Extra payments are applied after the required amortized payment to estimate faster payoff and interest savings.
Loan Payment Calculator
Use this loan payment calculator to estimate monthly payments, total interest, and total paid over the life of a loan.
Planning estimate
Live calculator
Loan payment
Monthly payment$500.95
$500.95 required payment plus extra payment.
Total interest$5,056.92
Estimated over 60 monthly payments.
Interest saved$0.00
Compared with paying only $500.95 per month.
What changes when you pay extra
The required payment is $500.95. With the extra amount entered, the payoff estimate uses $500.95 per month and finishes in 60 months instead of the scheduled 60 months.
Payoff summary
Shows how extra payments affect time and total interest.
| Measure | Estimate |
|---|---|
| Loan amount | $25,000.00 |
| Monthly payment used | $500.95 |
| Payoff time | 60 months |
| Total paid | $30,056.92 |
| Interest saved | $0.00 |
Amortization preview
Annual principal, interest, and remaining balance.
| Year | Principal | Interest | Ending balance |
|---|---|---|---|
| Year 1 | $4,281.58 | $1,729.81 | $20,718.42 |
| Year 2 | $4,613.97 | $1,397.42 | $16,104.46 |
| Year 3 | $4,972.16 | $1,039.22 | $11,132.29 |
| Year 4 | $5,358.16 | $653.22 | $5,774.13 |
| Year 5 | $5,774.13 | $237.25 | $0.00 |
Use this as a planning estimate. Taxes, fees, rates, account terms, provider policies, local rules, and timing can change real-world results.
How to use
Steps
- Enter the loan amount.
- Enter the annual interest rate.
- Enter the loan term in years.
- Add an optional extra monthly payment to estimate payoff time and interest savings.
Example
Sample calculation
Loan amount$25,000
Rate and term7.5% for 5 years
Monthly payment$500.95
Total interest$5,056.92
Calculator use
Best for
- Estimating affordability, payment, payoff, interest, APR, refinance, rent, or debt scenarios before a money decision.
- Comparing terms, rates, balances, fees, taxes, insurance, debt payments, or split shares with assumptions visible.
Before relying on it
Check first
- Treating an estimate as an approval, quote, credit decision, payoff statement, tax result, or legal payment obligation.
- Leaving out fees, escrow, insurance, property tax, PMI, minimum payments, compounding, promotional rates, or local rules.
- Comparing scenarios with different time horizons, upfront costs, credit assumptions, or one-time versus monthly costs.
Details
What to know before using the result
Payment typeAmortized principal and interest
The formula estimates a level monthly payment that pays interest and reduces principal over the selected term.
Interest patternMore interest early
Early payments usually include more interest because the outstanding balance is larger. Later payments shift more toward principal.
Extra paymentsPrincipal acceleration
Extra monthly principal can reduce total interest and shorten payoff time, but actual lender posting rules may vary.
Source notes
References used for this calculator
Benchmarks
How to read the result
Payment: Cash-flow check.
A manageable monthly payment still needs to fit the rest of the budget.
Total interest: True cost.
The amortization table shows how much interest accumulates over the term.
Extra principal: Payoff lever.
Extra monthly principal can shorten the payoff schedule and reduce interest.
Calculator accuracy
Methodology and assumptions
Formula, inputs, limitations and review record
Formula
Monthly payment = principal x monthly rate / (1 - (1 + monthly rate)^-months)
Inputs used
Loan amount, Interest rate, Loan term, Extra payment
Limitations
Money results are planning estimates. Actual taxes, account terms, rates, fees, timing, local rules, and provider policies can change the real-world result.
Review record
Method and sources checked on July 13, 2026. The documented method, source timing, validity conditions, and reliance limits were checked on this date.
Method provenanceEstimate · toolkitshelf.loan-payment-fixed-amortization.v1
- Maintained by
- Toolkit Shelf
- Calculation class
- Estimate
- Method version
- toolkitshelf.loan-payment-fixed-amortization.v1
- Source date
- Last reviewed May 28, 2024
- Source checked
- July 13, 2026
- Intended audience
- Borrowers comparing fixed-rate installment-loan payments, payoff time, total interest, and an optional constant extra monthly payment.
- Valid when
- The calculation assumes a fixed annual rate, monthly compounding, equal scheduled payments, and any extra amount applied monthly to principal. Fees, day-count conventions, payment dates, and variable rates are excluded.
- Reliance boundary
- This is not a lender quote, payoff statement, loan agreement, refinancing recommendation, or calculation of variable rates, fees, penalties, or lender-specific payment allocation.
- Data freshness
- The CFPB explanation of fixed-payment amortization was checked on July 13, 2026. No current lender rate or product term is fetched.
Cite this page
Toolkit Shelf. Loan Payment Calculator. https://toolkitshelf.com/tools/loan-payment-calculator
FAQ
Common questions
How is a loan payment calculated?
For an amortized loan, the payment is based on principal, monthly interest rate, and number of monthly payments.
Does this include taxes or fees?
No. This calculator estimates principal and interest only, unless you include fees in the loan amount.
What does extra monthly payment mean?
Extra monthly payment is added to the required payment and applied to principal, which can shorten the loan and reduce total interest.
Why does the amortization table matter?
It shows how each year shifts from mostly interest toward more principal, which helps compare term length and extra-payment scenarios.
Why can lender numbers differ from this result?
Lenders can use verified income, credit profile, reserves, fees, escrow rules, insurance, taxes, underwriting guidelines, and product-specific terms.
What assumption should I stress test?
Stress test rates, payment timing, fees, taxes, insurance, debt payments, and payoff timing before treating a loan or housing estimate as comfortable.
Leave passwords, account numbers, and private medical or tax information out of your report.