Business Loan Payment Calculator Guide: Monthly Payment, Total Interest and Amortization

A loan payment calculator turns four inputs, amount, interest rate, term and fees, into your monthly payment, total interest and total cost. The math is the standard amortization formula, and once you understand it you can sanity-check any lender's quote. The most useful habit is to run several scenarios: a shorter term, a lower rate, a smaller amount, and a version with fees added, so you see which lever changes the cost the most.

The formula

For a fixed-rate, fully amortizing loan with monthly payments:

Payment = P x r / (1 - (1 + r)^-n)

• P is the principal, the amount borrowed.
• r is the monthly interest rate, the annual rate divided by 12.
• n is the number of monthly payments, years times 12.

Total paid is payment times n. Total interest is total paid minus principal. Fees are added separately to get the total cost of borrowing.

Worked example

This uses illustrative inputs, not a quote. You borrow $100,000 at 9.5% for 5 years with $2,000 in upfront fees.

1. r = 0.095 / 12 = 0.0079167. n = 60.
2. (1 + r)^60 = about 1.6049, so (1 + r)^-60 = about 0.6231.
3. Payment = $100,000 x 0.0079167 / (1 - 0.6231) = about $2,100.
4. Total paid = $2,100 x 60 = about $126,000. Interest is about $26,000.
5. Adding the $2,000 fee, the total cost of borrowing is about $28,000.

You can reproduce this in the business loan payment calculator. A spreadsheet's PMT function gives the same answer: PMT(rate/12, years x 12, -amount).

Reading an amortization schedule

An amortization schedule lists every payment with its interest and principal portions. In the first year of the loan above, interest is the larger share. In the final year, almost all of the payment is principal. That is why prepaying early saves more than prepaying late.

The balances are approximations for this example. The calculator on this site produces a year-by-year balance table for your own inputs.

What-if scenarios worth running

1. Change the term. Try 3, 5 and 7 years with the same rate. A longer term lowers the payment but raises total interest. See repayment terms.

2. Change the rate by one or two points. Test how sensitive your payment is. A one-point rate change on a $100,000, five-year loan moves the payment by about $49 a month.

3. Add fees. Fees increase total cost without changing the monthly payment unless they are financed. A 2% fee on $100,000 is $2,000, which is a bigger share of cost on a shorter loan.

4. Test the stress case. If the loan is variable, run a rate 2 to 4 points higher. See fixed vs. variable.

5. Add extra payments. Paying an extra amount each month cuts the balance faster and saves interest, if there is no prepayment penalty. A simple way to estimate: reduce the term in the calculator until the payment matches your higher payment, then compare total interest.

What a basic calculator does not capture

• Daily or weekly payments. A monthly calculator approximates but does not model them exactly.
• Factor rates. These are fixed-fee products. Convert them to APR using the method in factor rates vs. APR.
• Interest-only periods and balloon payments. These change the schedule.
• Variable rates. The calculator assumes a constant rate.
• Day-count conventions. Some commercial loans calculate interest on actual days over a 360-day year, which slightly raises the effective cost compared with a 30/360 method.
• Financed fees. If fees are rolled into the loan, the principal and interest change.
• Tax effects. Business loan interest may be tax-deductible, subject to limits. A CPA can tell you how it applies to your situation.

Using the calculator to compare offers

1. Enter each offer's amount, rate, term and fees.
2. Record the monthly payment, total interest and total cost.
3. Compare the total cost and the monthly payment against your cash flow.
4. Check the lender's own disclosure for APR and compare it with the rate and fees you entered.
5. Run the same offers with a shorter hold period if you might repay early.

Checking a lender's quote

If a lender quotes a payment that differs materially from the calculator, find out why. Reasons can include financed fees, a different compounding method, a different payment date, a variable rate, a balloon payment or an error. Ask for the amortization schedule in writing.

Connecting the payment to your business

Once you know the payment, test it against income. If your net operating income is $180,000 and your payment is $25,200 a year, DSCR for this loan alone is about 7.1, but your total across all debts matters. See how much you can borrow. Then use the break-even calculator to see whether the profit from the loan outweighs its cost.

Mistakes to avoid

• Entering the term in months where years are expected, or the reverse.
• Forgetting to convert a percentage correctly, such as entering 0.095 where 9.5 is required.
• Ignoring fees or deducting them from proceeds without noting that you receive less than the loan amount.
• Treating the result as a commitment. Only the lender's loan agreement is binding.

When to consult a professional

For larger loans, have an accountant model the effect on cash flow and taxes, and ask the lender's loan officer to walk through the amortization schedule with you.

FAQ

How do I calculate a monthly business loan payment?

Use the formula above or a spreadsheet's PMT function with the monthly rate, number of payments and loan amount.

Does the calculator include fees?

The calculator on this site adds the fees you enter to the total paid but does not finance them into the balance. Check whether your lender does.

Why is my lender's payment different?

Differences can come from fees, rate type, day-count method, balloon structure or rounding. Ask for the amortization schedule.

Is business loan interest tax-deductible?

Generally interest on business debt used for business purposes can be deductible, subject to rules and limits. Ask a CPA or see IRS guidance.

Sources

• Internal Revenue Service — business interest expense guidance
• Consumer Financial Protection Bureau — loan cost education
• U.S. Small Business Administration — loan program information
• Federal Reserve — interest-rate data