Loan Calculator | Toolcroft

How to use this tool

Enter the loan amount. Type the principal - the amount you are borrowing. Do not include a dollar sign; just the number.
Enter the annual interest rate. Type the annual interest rate as a percentage, e.g., 7.5 for 7.5%. Check your loan offer for the APR or note rate.
Set the loan term. Choose years or months and enter the duration. Most mortgages are 15 or 30 years; auto loans are commonly 36–72 months.
Read the results. The monthly payment, total interest paid, and total amount paid update instantly as you type.
Estimate extra principal payments. Open Pay extra to add a monthly amount or a one-time payment in a chosen month. Compare the estimated interest and payoff time with the original schedule; confirm with your servicer how extra funds are applied.

How to use the loan calculator

Enter the loan amount (the principal you are borrowing), the annual interest rate as a percentage, and the loan term in years or months. Monthly payment, total interest, and total cost update immediately as you type. Use the years/months toggle to switch term units. A 30-year mortgage and a 360-month mortgage produce identical results.

How monthly payment is calculated

The standard fixed-rate amortization formula is:

M = P × r(1+r)ⁿ / ((1+r)ⁿ − 1)

where M is the monthly payment, P is the loan principal, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. When the interest rate is 0%, the formula simplifies to M = P ÷ n.

Each payment covers that month's interest first, with the remainder reducing the principal. Early payments are mostly interest; later payments are mostly principal. The monthly payment amount stays constant throughout the loan term.

Common loan examples

These examples use the same fixed-rate formula as the calculator and assume monthly payments with no added fees.

Loan	Amount	Rate	Term	Monthly payment	Total interest
30-yr mortgage	$300,000	7%	30 yr	$1,995.91	$418,527
15-yr mortgage	$300,000	6.5%	15 yr	$2,613.32	$170,398
Auto loan	$35,000	6%	60 mo	$676.65	$5,599
Personal loan	$10,000	10%	36 mo	$322.67	$1,616
Student loan	$30,000	5.5%	10 yr	$325.58	$9,069

Biweekly payments

Instead of making one full monthly payment, pay half your monthly payment every two weeks. Because there are 52 weeks per year, you make 26 half-payments - equivalent to 13 full monthly payments instead of 12. If the servicer applies each half-payment promptly, the extra payment can shorten the loan and reduce interest. The amount saved depends on the balance, rate, and when payments are credited; this page's extra-principal controls can estimate a monthly or one-time extra payment.

Confirm with your lender that they accept biweekly payments and apply them as principal reduction - some servicers hold biweekly payments until a full month's payment is accumulated, which eliminates the benefit.

Points and origination fees

The APR (Annual Percentage Rate) is a more complete measure of a loan's cost than the nominal interest rate because it includes origination fees, points, and other lender charges. One discount point = 1% of the loan principal paid upfront to lower the interest rate (typically by 0.25% per point). The APR spreads these costs over the full loan term, making apples-to-apples comparison between loan offers possible. Always compare APRs - not just stated rates - when shopping for a loan.

Frequently asked questions

How is the monthly payment calculated?

The standard amortization formula is M = P × (r(1+r)ⁿ) / ((1+r)ⁿ − 1), where P is the loan principal, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments. When the interest rate is 0%, the payment is simply P ÷ n.

What is the monthly payment on a $200,000 loan at 7% for 30 years?

At 7% annual interest over 30 years (360 months), the monthly payment is approximately $1,330.60. Using the unrounded payment for the totals, you would pay about $279,018 in interest and $479,018 overall. The calculator displays the monthly payment rounded to cents.

How does loan term affect my monthly payment?

A shorter term increases the monthly payment but reduces the total interest paid. A longer term lowers the monthly payment but you pay more interest overall. For example, a $20,000 car loan at 6%: 48-month term ≈ $469.70/month ($2,546 total interest); 72-month term ≈ $331.46/month ($3,865 total interest).

What is total interest paid?

Total interest is the sum of all interest charges over the entire loan term: total payment minus the original principal. It shows the true cost of borrowing. On a long mortgage, total interest can exceed the original loan amount.

Can I use this for a mortgage, car loan, or personal loan?

Yes - the formula works for any fixed-rate, fixed-term installment loan: mortgages, auto loans, personal loans, student loans. Variable-rate loans require recalculation at each rate change. This calculator assumes monthly compounding and equal payments throughout the term.