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Loan Calculator

This loan calculator estimates your monthly payment, total interest, and total repayment cost for a fixed-rate installment loan. Enter your loan amount, annual interest rate, and loan term, and the tool applies a standard amortization formula to project your payment schedule. It works for personal loans, auto loans, student loans, or any fixed-rate loan with equal monthly payments.

FinanceBy Reviewed by CalcTide Editorial Review Team

Quick answer

Monthly payment depends on three inputs: principal, annual interest rate, and loan term in years.

What this tells you

  • •Monthly payment depends on three inputs: principal, annual interest rate, and loan term in years.
  • •Longer terms lower the monthly payment but increase the total interest paid over the life of the loan.
  • •A higher interest rate raises both the monthly payment and the total interest, even with the same principal.
  • •This calculator projects principal and interest only. Lender fees, taxes, and insurance are not included.
  • •Use the result as a planning estimate before comparing offers from actual lenders.

How to Use

  1. 1Enter the loan amount (principal) you plan to borrow or currently owe.
  2. 2Enter the annual interest rate as a percentage, such as 6.5 for 6.5%.
  3. 3Enter the loan term in years, such as 5 for a 5-year loan.
  4. 4Calculate to see your estimated monthly payment, total amount paid, and total interest.
  5. 5Adjust the term or rate to compare how they change your monthly payment and total cost.

How It Works

Formula

M = P x [r(1+r)^n] / [(1+r)^n - 1]

M is the monthly payment, P is the loan principal, r is the monthly interest rate (annual rate divided by 12 and divided by 100), and n is the total number of monthly payments (years multiplied by 12). This formula assumes a fixed interest rate and equal monthly payments for the full term, which is how most personal, auto, and standard installment loans are structured. If the interest rate is 0%, the monthly payment is simply the principal divided by the number of months.

Calculation note: values are processed in the order shown above, using the current input units.

Worked Examples

Personal loan example

Principal$25,000
Rate6%
Term5 years
ResultMonthly: $483.32

Over 60 monthly payments at a 0.5% monthly rate, the total amount paid comes to $28,999.20, which includes $3,999.20 in interest. This is a common setup for a mid-size personal or debt-consolidation loan.

Short-term loan example

Principal$10,000
Rate8%
Term2 years
ResultMonthly: $452.27

With a shorter 24-month term, the monthly payment is higher relative to the principal, but total interest stays low at $854.55. Shorter terms trade a higher monthly payment for a lower total cost.

Large, long-term loan example

Principal$300,000
Rate6.5%
Term30 years
ResultMonthly: $1,896.20

Stretching a large loan over 30 years keeps the monthly payment manageable, but total interest reaches $382,633.47, more than the original principal. This pattern is typical for mortgage-length terms and shows why term length matters as much as rate.

Zero-interest loan example

Principal$15,000
Rate0%
Term3 years
ResultMonthly: $416.67

With no interest charged, the monthly payment is just the principal divided evenly across 36 months, and total interest is $0. Promotional 0% financing offers use this same math.

Common mistakes

  • Entering the annual interest rate as if it were the monthly rate, which sharply overstates the payment.
  • Ignoring lender fees, origination charges, and insurance add-ons that raise the real cost above this estimate.
  • Choosing a longer term based only on the lower monthly payment without comparing total interest paid.
  • Assuming a shown rate is the same as APR, which can include additional fees baked into the cost of borrowing.
  • Forgetting that extra principal payments can shorten a loan and cut total interest, which this basic estimate does not model.

Limitations

This calculator assumes a fixed interest rate and equal monthly payments for the full term. It does not account for lender fees, origination charges, taxes, insurance products, variable rates, or extra principal payments, all of which can change your actual cost.

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Drop this single line where you want the calculator to appear. It is responsive, mobile-friendly, resizes automatically, and is free to use with attribution.

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Frequently Asked Questions

No. It estimates principal-and-interest repayment only. Origination fees, closing costs, and insurance products are not included and can raise your actual monthly payment.
The payment becomes the principal divided evenly by the total number of months, since no interest accrues. This mirrors how promotional 0% APR financing works.
Interest accrues on the remaining balance every month, so spreading payments over more months means more months of accrued interest, even though each payment is smaller.
Not necessarily. APR can include lender fees on top of the base interest rate, so your real cost of borrowing may be higher than what this calculator shows using rate alone.
You can estimate principal and interest for a mortgage-length term, but a dedicated mortgage calculator will better handle property taxes, insurance, and PMI that typically apply to home loans.
This calculator does not model extra payments directly, but paying above the scheduled amount reduces the outstanding balance faster and lowers total interest over the life of the loan.
Payment differences usually come from a different interest rate, term length, or principal amount. Even a small rate difference compounds noticeably over a multi-year term.
Total paid is every monthly payment added together over the full term. Total interest is that total minus your original principal, showing the actual cost of borrowing.
Yes, indirectly. Your credit score influences the interest rate a lender offers you, and this calculator only projects payments for the rate you enter. Check your actual rate with a lender before relying on the estimate.
Yes. Run the calculator once for each offer's principal, rate, and term, then compare the monthly payment and total interest side by side to see which option costs less overall.
It estimates loan calculator outputs using the visible inputs and formula assumptions on this page.

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