Loan Interest Calculator

Calculate monthly payment and total interest from loan principal, rate, term, and repayment method.

Note: A financial reference calculation. Actual repayment varies by lender terms, fees, early repayment, daily proration, and rate changes.

Category: Calculators

When to use?

Use it to compare loan products such as mortgages and personal loans, or to see the total-interest difference between equal-payment and equal-principal methods.

How to use

  • Enter the loan principal.
  • Enter the annual rate (%) and term (months).
  • Choose the repayment method (equal payment or equal principal).
  • The monthly payment and total interest are calculated.

Input Explanation

Enter the total loan, annual interest rate, term, and repayment method (equal payment, equal principal, etc.).

Calculation Basis

Equal payment: the same amount each month. Equal principal: the same principal plus declining interest each month. Equal principal has less total interest.

Usage Examples

  • Plan repayment - Compare total interest and payments for equal-payment vs. equal-principal methods.
  • Compare loan products - Compare monthly payments and total interest across rates and terms.
  • Check affordability - Confirm in advance whether the monthly payment is manageable.

Examples

  • Principal 100,000,000, 4%/yr, 30 yrs, equal payment → ~477,415/month, total interest ~71,870,000
  • Principal 30,000,000, 5%/yr, 5 yrs, equal principal → ~625,000 first month, total interest ~3,810,000

Cautions

  • Actual interest varies with spread/preferential rates, early-repayment fees, grace periods, and daily proration. Check the lender's official terms before borrowing.
  • This is a simple estimate from your inputs and a general formula; verify officially before any real or commercial use.

Guides

Equal payment vs. equal principal

Equal payment keeps the monthly amount constant; equal principal keeps the monthly principal constant, making early payments larger.

Difference from real repayment

It is a simple calculation that ignores lender fees, early repayment, rate changes, and daily proration.

FAQ

Does it match the lender's calculation?

It is a simple calculation excluding fees, early repayment, and daily proration.

How do equal payment and equal principal differ?

Equal payment is the same amount monthly; equal principal splits the principal evenly, so early payments are larger.

Which method has less total interest?

Generally equal principal, because it repays the principal faster.

Is a grace period reflected?

This tool assumes repayment starts immediately with no grace period. A grace period increases actual interest.

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