Monthly Payment & Total Cost
Last reviewed: May 2026
A loan calculator estimates your monthly payment, total interest paid, and full amortization schedule for any fixed-rate installment loan — personal loans, auto loans, student loans, or any other borrowing with a set term. By entering the loan amount, interest rate, and repayment period, you can see exactly how much each payment costs, how much goes to interest versus principal, and what the loan truly costs over its full life. The difference between a 4-year and 6-year auto loan on the same amount can be tens of thousands of dollars — this calculator makes those tradeoffs visible before you sign.1
Every monthly loan payment covers two components: the interest accrued since your last payment, and a reduction of your principal balance. The formula for calculating monthly payments is M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is the principal, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of payments. Early in the loan, most of your payment goes to interest — later, that ratio shifts toward principal. On a $25,000 loan at 7% over 5 years, your first payment of $495 puts $349 toward principal and $146 toward interest. By payment 50, $488 goes to principal and only $7 to interest.2
| Loan Amount | Rate | Term | Monthly Payment | Total Interest | Total Cost |
|---|---|---|---|---|---|
| $10,000 | 6% | 3 years | $304 | $950 | $10,950 |
| $10,000 | 6% | 5 years | $193 | $1,600 | $11,600 |
| $25,000 | 7% | 4 years | $598 | $3,728 | $28,728 |
| $25,000 | 7% | 6 years | $427 | $5,718 | $30,718 |
| $50,000 | 8% | 5 years | $1,014 | $10,832 | $60,832 |
| $50,000 | 8% | 7 years | $780 | $15,494 | $65,494 |
The interest rate is the cost of borrowing the principal alone. The APR (Annual Percentage Rate) includes the interest rate plus additional fees — origination fees, closing costs, and other charges — spread over the loan's life. A loan advertised at 6.5% interest with a 2% origination fee might have an APR of 7.3%. The Truth in Lending Act requires lenders to disclose the APR, making it the correct number for comparing offers across lenders. Two loans with the same interest rate can have very different APRs depending on their fee structures. Use our APR Calculator to compare the true cost of different offers.3
Any extra payment goes directly to principal, reducing the balance that future interest is calculated on. Even one extra payment per year on a 60-month loan can cut 4–6 months off the payoff date and save hundreds in interest. Some lenders require you to specify that extra payments reduce principal — confirm this before making them. Biweekly payments (half your monthly payment every two weeks) result in 26 half-payments per year — the equivalent of 13 full monthly payments instead of 12, naturally adding an extra payment each year without feeling the pinch.
Refinancing to a lower rate can significantly reduce total interest, but only if the savings exceed the closing costs before you pay off or refinance again. The break-even formula is straightforward: closing costs ÷ monthly savings = months to recoup. If refinancing costs $1,500 and saves $75/month, you break even in 20 months — worth it only if you'll keep the loan at least that long.
The term length is the single biggest lever affecting your total cost. A $30,000 loan at 7% costs $594/month over 5 years ($5,618 total interest) versus $348/month over 10 years ($11,806 total interest) — nearly doubling the interest paid for those lower monthly payments. The general guideline is to choose the shortest term where payments stay below 10–15% of your monthly take-home income, leaving room for emergencies and other financial goals.
| $30,000 at 7% | Monthly Payment | Total Interest | Interest as % of Loan |
|---|---|---|---|
| 3-year term | $926 | $3,349 | 11.2% |
| 5-year term | $594 | $5,618 | 18.7% |
| 7-year term | $454 | $8,100 | 27.0% |
| 10-year term | $348 | $11,806 | 39.4% |
Fixed-rate loans lock your interest rate for the entire term, making monthly payments predictable — ideal for longer-term loans where rate increases could strain your budget. Variable-rate loans start with a lower rate that resets periodically based on a benchmark index like SOFR or Prime. Variable rates make sense when you plan to pay off the loan before the adjustment period, or when rates are expected to decline. The risk is substantial: a 2% rate increase on a $50,000 balance adds roughly $83/month. When in doubt, fixed rates provide the certainty that lets you budget with confidence.4
All fixed-rate installment loans use the same formula: Payment = P × [r(1+r)^n] / [(1+r)^n − 1]. The variables are straightforward — borrow less, get a lower rate, or extend the term to lower payments. But extending the term always increases total interest. A $25,000 auto loan at 6.5%: over 36 months costs $766/month with $2,572 interest; over 72 months, $422/month but $5,384 interest — more than double.
The interest rate is the base cost. APR includes the rate plus fees (origination, points, closing costs) spread over the term. A mortgage at 6.75% with $4,000 in fees might have a 6.95% APR. Federal law requires APR disclosure. Always compare APR to APR — never mix APR and interest rate comparisons.
On a $300,000 mortgage, the difference between a 760+ and 620 score can be 1.5-2 percentage points — $300-400/month and $100,000+ in total interest. For auto loans, the spread is wider: a 750 score might get 5.5% while 580 faces 14-18%. Spending 3-6 months improving credit before a major loan saves tens of thousands. Fastest improvement: reduce credit card utilization below 30% of limits — can boost scores 20-40 points within one billing cycle.
Secured loans (backed by collateral) offer lower rates: mortgages 6-8%, auto loans 5-9%. Unsecured loans carry higher risk for lenders and higher rates: personal loans 8-15%, credit cards 18-28%. The spread is typically 5-15 percentage points — on $20,000, that's $1,000-3,000/year in extra interest.
Three common approaches: fixed extra payment ($100/month extra), round-up method (rounding $422 to $500), lump-sum payments (applying bonuses or refunds). On a $25,000 auto loan at 6.5% over 60 months, adding $75/month extra saves $760 interest and pays off 11 months early. Always specify that extra payments apply to principal only — some lenders default to applying extra toward future payments, which doesn't reduce interest.
The stated interest rate on a loan doesn't capture the full cost of borrowing. Origination fees (typically 0.5-2% of the loan amount), processing fees, and documentation charges add upfront costs that increase the effective rate. A $200,000 mortgage at 6.5% with a 1% origination fee ($2,000) has an APR closer to 6.62% — the APR calculation spreads origination costs across the loan term to show the true annual cost. For personal loans, origination fees can reach 6-8%, meaning a $10,000 loan may fund only $9,200-9,400 after the fee is deducted from proceeds. Always compare APR rather than interest rate when evaluating loan offers from different lenders, as the lowest rate may not be the cheapest loan after fees.
The stated interest rate on a loan doesn't capture the full cost of borrowing. Origination fees (typically 0.5-2% of the loan amount), processing fees, and documentation charges add upfront costs that increase the effective rate. A $200,000 mortgage at 6.5% with a 1% origination fee ($2,000) has an APR closer to 6.62% — the APR calculation spreads origination costs across the loan term to show the true annual cost. For personal loans, origination fees can reach 6-8%, meaning a $10,000 loan may fund only $9,200-9,400 after the fee is deducted from proceeds. Always compare APR rather than interest rate when evaluating loan offers from different lenders, as the lowest rate may not be the cheapest loan after fees.
The stated interest rate on a loan doesn't capture the full cost of borrowing. Origination fees (typically 0.5-2% of the loan amount), processing fees, and documentation charges add upfront costs that increase the effective rate. A $200,000 mortgage at 6.5% with a 1% origination fee ($2,000) has an APR closer to 6.62% — the APR calculation spreads origination costs across the loan term to show the true annual cost. For personal loans, origination fees can reach 6-8%, meaning a $10,000 loan may fund only $9,200-9,400 after the fee is deducted from proceeds. Always compare APR rather than interest rate when evaluating loan offers from different lenders, as the lowest rate may not be the cheapest loan after fees.
The stated interest rate on a loan doesn't capture the full cost of borrowing. Origination fees (typically 0.5-2% of the loan amount), processing fees, and documentation charges add upfront costs that increase the effective rate. A $200,000 mortgage at 6.5% with a 1% origination fee ($2,000) has an APR closer to 6.62% — the APR calculation spreads origination costs across the loan term to show the true annual cost. For personal loans, origination fees can reach 6-8%, meaning a $10,000 loan may fund only $9,200-9,400 after the fee is deducted from proceeds. Always compare APR rather than interest rate when evaluating loan offers from different lenders, as the lowest rate may not be the cheapest loan after fees.
The stated interest rate on a loan doesn't capture the full cost of borrowing. Origination fees (typically 0.5-2% of the loan amount), processing fees, and documentation charges add upfront costs that increase the effective rate. A $200,000 mortgage at 6.5% with a 1% origination fee ($2,000) has an APR closer to 6.62% — the APR calculation spreads origination costs across the loan term to show the true annual cost. For personal loans, origination fees can reach 6-8%, meaning a $10,000 loan may fund only $9,200-9,400 after the fee is deducted from proceeds. Always compare APR rather than interest rate when evaluating loan offers from different lenders, as the lowest rate may not be the cheapest loan after fees.
→ Compare total cost, not just monthly payments. A 72-month auto loan has lower monthly payments than a 48-month loan, but you'll pay thousands more in interest. Always look at the "total interest paid" figure.
→ Factor in all fees. Origination fees, closing costs, and prepayment penalties affect your true cost. Add origination fees to the principal when calculating to see the real effective rate.
→ Use the amortization table to plan extra payments. Even $50–100 extra per month toward principal can shave years off a loan and save significant interest. Our Extra Payment Calculator shows exactly how much.
→ Check your debt-to-income ratio first. Lenders typically want your total monthly debt payments (including the new loan) below 36% of gross income. Use our DTI Calculator before applying.
See also: Personal Loan Calculator · APR Calculator · Business Loan Calculator · Boat Loan Calculator · Mortgage Calculator · Auto Loan Calculator