Loan Calculator

Whether you are planning a major purchase, consolidating debt, or covering an unexpected expense, understanding your monthly payment before you borrow is essential.

Reviewed by: CalcMojo Editorial Team

The CalcMojo personal loan calculator helps you estimate exactly what you will owe each month based on your loan amount, interest rate, and repayment term. Enter your numbers above and get an instant breakdown of your monthly payment, total interest, and the full cost of borrowing.

This calculator works for virtually any type of installment loan. Use it for personal loans, student loans, auto loans, and small business loans — any fixed-rate loan where you repay a set amount each month over a defined term. Unlike simple interest calculators, this tool uses the standard amortization formula to give you the same numbers your lender uses when generating your loan agreement.

Not sure where to start? Try entering a few different scenarios. Adjust the loan amount up or down, test different interest rates, or compare a 36-month term against a 60-month term. You will quickly see how each variable affects your monthly obligation and the total amount you pay over the life of the loan. The goal is to help you borrow smarter — finding the balance between an affordable monthly payment and the lowest possible total cost.

How Personal Loan Interest Works

When you take out a personal loan with a fixed interest rate, your lender calculates your monthly payment using the standard amortization formula, often referred to as the PMT (payment) formula in financial mathematics. The formula is:

M = P[r(1+r)^n] / [(1+r)^n – 1]

Where:

• M = monthly payment
• P = principal (the amount you borrow)
• r = monthly interest rate (annual rate divided by 12)
• n = total number of monthly payments (loan term in months)

This formula ensures that each monthly payment covers both a portion of the principal and the interest accrued since your last payment. Early in the loan, most of your payment goes toward interest. As you pay down the balance, the interest portion shrinks and more of each payment reduces your principal. This gradual shift is called amortization.

For example, suppose you borrow $15,000 at 8% annual interest for 48 months. Your monthly interest rate is 0.08 / 12 = 0.00667. Plugging these values into the formula yields a monthly payment of approximately $366. Over 48 months, you will pay a total of about $17,568 — meaning $2,568 goes to interest alone.

Understanding amortization matters because it reveals an important truth: on a longer loan term, you pay less per month but significantly more in total interest. Knowing this helps you make an informed decision about how quickly you want to eliminate your debt.

Fixed vs Variable Rate Loans

Not all loans charge interest the same way, and the distinction between fixed and variable rates fundamentally changes your repayment experience.

Fixed-rate loans lock in your interest rate for the entire term. Your monthly payment never changes, which makes budgeting straightforward. Most personal loans from banks, credit unions, and online lenders are fixed-rate products. The CalcMojo personal loan calculator assumes a fixed rate, so the payment it generates is the exact amount you would pay every month from the first payment to the last.

Variable-rate loans (also called adjustable-rate loans) tie your interest rate to a benchmark index such as the prime rate or SOFR (Secured Overnight Financing Rate). When the benchmark moves, your rate adjusts — typically on a monthly or quarterly schedule. Variable rates often start lower than fixed rates, which can be appealing. However, if rates rise, your monthly payment increases and your total borrowing cost can climb well beyond your original estimate.

Variable-rate loans are more common in certain product categories: home equity lines of credit (HELOCs), some student loans, and adjustable-rate mortgages. If you are evaluating a variable-rate offer, use this calculator to model multiple scenarios. Calculate your payment at the initial rate, then recalculate at a rate two or three percentage points higher. If you can comfortably afford the higher payment, the variable option may be worth considering. If the higher payment would strain your budget, a fixed rate offers more predictable protection.

How to Compare Loan Offers

Shopping for a loan means comparing more than just the interest rate printed on the offer letter. Two concepts are critical for making an apples-to-apples comparison: APR and total cost of borrowing.

APR (Annual Percentage Rate) includes the interest rate plus most fees the lender charges — origination fees, application fees, and certain closing costs. Federal law (the Truth in Lending Act) requires lenders to disclose the APR, making it the single best number for comparing the true cost of competing offers. A loan with a 7.5% interest rate and a 3% origination fee may carry an APR of 9.1%, while a loan at 8.0% with no fees may have an APR of 8.0%. The second offer is cheaper despite the higher stated rate.

Total cost comparison goes one step further. Use this calculator to compute the total amount paid (principal plus interest) for each offer over the full loan term. Then add any fees not captured in the APR. The offer with the lowest total outlay is objectively the cheapest — even if its monthly payment is slightly higher due to a shorter term.

When comparing offers, also pay attention to prepayment penalties. Some lenders charge a fee if you pay off your loan early. If you think you might make extra payments or pay off the balance ahead of schedule, choose a lender with no prepayment penalty so you can save on interest without incurring additional costs.

For home purchases, consider using our Mortgage Calculator to compare mortgage-specific offers that include property taxes and insurance in the payment estimate.

Total Cost of Borrowing

One of the most common mistakes borrowers make is focusing exclusively on the monthly payment. A lower monthly payment feels more affordable, but it almost always means a longer repayment period — and a longer period means more months of accruing interest.

Consider this comparison for a $20,000 personal loan at 10% APR:

• 36-month term: Monthly payment of $645. Total paid: $23,220. Total interest: $3,220.
• 60-month term: Monthly payment of $425. Total paid: $25,500. Total interest: $5,500.
• 84-month term: Monthly payment of $332. Total paid: $27,888. Total interest: $7,888.

Extending the term from 36 months to 84 months reduces the monthly payment by nearly half, but it more than doubles the interest you pay. That extra $4,668 in interest is real money that could go toward savings, investments, or other financial goals.

This is why financial advisors consistently recommend choosing the shortest loan term you can comfortably afford. Use the calculator to find your "sweet spot" — the term length where the monthly payment fits your budget without unnecessarily inflating the total cost.

To see how interest compounds over time across different financial products, try our Compound Interest Calculator for a broader perspective on how time and rate interact.

When to Consider a Personal Loan

Personal loans are unsecured installment loans, meaning they do not require collateral like a house or car. This makes them versatile but also typically more expensive than secured loans. Here are the most common situations where a personal loan makes financial sense:

Debt consolidation. If you carry balances on multiple credit cards with high interest rates (often 20% or more), a personal loan at 8-12% can significantly reduce your interest costs. You replace several payments with one fixed monthly payment, simplify your finances, and potentially pay off the debt faster. Use our Debt Payoff Calculator to compare your current payoff timeline against a consolidation scenario.

Home improvement. For renovations that do not justify a home equity loan or HELOC — kitchen updates, bathroom remodels, energy efficiency upgrades — a personal loan provides the funds without putting your home at risk as collateral. Loan amounts typically range from $1,000 to $50,000, covering most mid-range projects.

Emergency expenses. Medical bills, urgent car repairs, or other unexpected costs can arrive without warning. A personal loan with a fixed repayment schedule is often preferable to credit card debt because the interest rate is lower and the structured payments create a clear payoff timeline.

Major life events. Weddings, relocations, and similar large planned expenses can be financed with a personal loan when savings fall short. The key is to borrow only what you need and choose the shortest term you can afford.

When a personal loan may not be the best choice: If you have equity in your home, a HELOC or home equity loan will almost always offer a lower rate. If you need a small amount (under $1,000), a 0% introductory APR credit card may be more cost-effective. And if you are borrowing to invest or speculate, the risk usually outweighs the potential reward.

This calculator provides estimates for informational purposes only. It is not financial advice. Results may not reflect your actual loan terms, tax situation, or investment returns. Consult a licensed financial advisor, CPA, or mortgage professional before making financial decisions.

Sources & Methodology

Loan payments calculated using the standard amortization formula (PMT): M = P[r(1+r)^n]/[(1+r)^n-1]. This formula is the industry-standard method used by banks, credit unions, and financial institutions to determine fixed monthly payments on installment loans. Reference: Corporate Finance Institute, Investopedia Amortization Formula.

Default rates shown are illustrative. Always verify current rates with your lender. Data accurate as of: March 2026