Loan

Turning Principal, Rate, and Term Into a Fixed Payment

A fixed loan payment (sometimes called an EMI, for “Equated Monthly Installment”) is calculated from the loan amount, interest rate, and term using the standard amortization formula. Enter those three figures and this calculator shows your fixed monthly payment — plus how much you’ll pay in total over the life of the loan and how much of that is interest.

This works for any fixed-rate installment loan with a monthly payment schedule — a personal loan, an auto loan, or similar — not just a mortgage. If you’re financing a home specifically, the dedicated Mortgage Calculator adds extra-payment scenarios and other home-loan-specific detail this general-purpose version doesn’t.

The Formula

The standard fixed-rate amortization formula:

$$M = \vA{P} \times \frac{\vB{r}(1+\vB{r})^{\vC{n}}}{(1+\vB{r})^{\vC{n}} - 1}$$

where $M$ is the monthly payment, $\vA{P}$ is the loan principal, $\vB{r}$ is the monthly interest rate (the annual rate divided by 12), and $\vC{n}$ is the total number of monthly payments (the term in months).

Worked Example

A $20,000 loan at 8% annual interest over 60 months (5 years):

1. Monthly rate: $\vB{r} = 8\% \div 12 \approx 0.667\%$.
2. Applying the formula gives a monthly payment of about $405.53.

Over the full 60 months, that’s about $24,331.67 paid in total — roughly $4,331.67 of which is interest on top of the amount borrowed.

Key Factors to Consider

• Loan term and total interest paid trade off against each other directly. A longer term lowers the monthly payment but increases the total interest paid over the life of the loan, since interest accrues for more months — a shorter term raises the payment but can meaningfully reduce total interest, which is worth weighing against monthly-budget affordability rather than optimizing for the lowest payment alone.
• Your credit score is one of the biggest factors in what rate you actually qualify for. Lenders price fixed-rate installment loans largely based on creditworthiness — checking your credit report and score before applying, and shopping multiple lenders, can meaningfully change the rate (and therefore the payment) you’re offered for the same loan amount.
• Secured loans (backed by collateral, like an auto loan) typically carry lower rates than unsecured loans (like most personal loans). The lender’s risk is lower when there’s an asset to repossess if payments stop, which usually translates into a lower interest rate compared to an unsecured loan of similar size and term.
• Early payoff can save real interest, but check for a prepayment penalty first. Since interest accrues on the remaining balance each month, paying extra toward principal reduces future interest — but some loans charge a fee for paying off early, which can offset some or all of that savings.

Common Mistakes

• Confusing the interest rate with the APR. The rate used here drives the monthly payment, but a real loan offer’s APR (which folds in origination fees and other upfront costs) is usually higher and is the more accurate number for comparing two competing loan offers.
• Assuming an extra payment shortens the term automatically. Making one extra payment reduces the remaining balance, which shortens the payoff time — but only if the loan is actually recast or the extra amount keeps being applied every month; a single one-time extra payment alone doesn’t change the required minimum payment going forward.
• Not checking for a prepayment penalty. Some loans charge a fee for paying off the balance early — this calculator assumes extra payments go straight to reducing the balance with no penalty, which isn’t true for every loan.

Useful to Know

• Financing a home specifically, rather than a personal or auto loan? Mortgage Calculator covers the same amortization math plus extra-payment scenarios and PMI-adjacent detail this general-purpose calculator leaves out.
• Comparing this loan’s stated rate against a real offer’s all-in cost? Annual Percentage Rate (APR) Calculator folds origination fees and other upfront costs into a single comparable rate.
• Curious whether this loan fits your overall budget alongside other debts? Debt-to-Income (DTI) Calculator weighs this payment against your gross income and existing obligations.