How this calculator works
Before you sign for a business loan, you should know exactly what it will cost you each month and over its full term. This Business Loan Calculator uses the standard amortization formula to compute your monthly payment, total interest paid, and the complete repayment schedule — so there are no surprises after the ink dries. Loan agreements are dense legal documents, but the math underneath is simple: principal plus interest, paid in equal installments over time.
Enter the loan amount, annual interest rate, and term in years. The calculator instantly shows your monthly payment, total amount repaid (principal + interest), and total interest cost. The amortization breakdown shows how much of each early payment goes to interest versus principal — a useful reality check for anyone considering a long-term loan. In the first year of a 30-year mortgage, for example, over 80% of each payment is interest. By the final year, less than 5% is.
Most business loans use fixed rates and equal monthly payments. SBA 7(a) loans typically run 5-25 years at rates tied to prime plus a margin. Equipment loans often run 3-7 years. Lines of credit work differently (interest-only on the balance) and aren't suited to this calculator. Always confirm whether your rate is fixed or variable before signing — variable rate loans can spike when interest rates rise, doubling or tripling your monthly payment.
The formula
Monthly Payment = P x [r(1+r)^n] / [(1+r)^n - 1]
Where P = principal, r = monthly interest rate (annual / 12), n = total number of payments (years x 12)
Total Repaid = Monthly Payment x n
Total Interest = Total Repaid - Principal
Interest Portion of Payment = Remaining Balance x r
Principal Portion of Payment = Monthly Payment - Interest Portion
Worked example
A $50,000 equipment loan at 8% APR for 5 years: monthly rate = 0.08 / 12 = 0.00667, n = 60 payments. Monthly payment = $50,000 x [0.00667 x (1.00667)^60] / [(1.00667)^60 - 1] = $1,013.82. Total repaid = $60,829. Total interest = $10,829 over 5 years.
The amortization reveals the time value of money: the first payment is $333 interest and $681 principal. The last payment is $7 interest and $1,007 principal. This is why early repayment saves so much interest — paying an extra $100/month in year 1 reduces principal rapidly, saving years of interest on the back end.
Compare scenarios: a 7-year term at the same rate drops the payment to $764/month but raises total interest to $14,143. A 3-year term raises the payment to $1,566/month but cuts interest to $6,398. Choose based on your cash flow: shorter terms cost less total but strain monthly budgets; longer terms ease monthly pressure but cost more overall.
Methodology and sources
The amortization formula used here is the standard fixed-payment loan formula taught in finance and used by every bank, credit union, and SBA lender. The formula derives from the present value of an annuity: the loan amount equals the present value of all monthly payments, discounted at the monthly interest rate.
The formula assumes a fixed interest rate and equal monthly payments. For variable-rate loans, payments may change when the rate adjusts. For interest-only loans, only interest is paid during the interest-only period, with principal due as a balloon at the end.
Sources: Principles of Corporate Finance by Brealey, Myers, Allen; SBA 7(a) loan program documentation; Federal Reserve consumer credit guidance.
Industry benchmarks
Typical business loan rates and terms (2024):
- SBA 7(a) loans: Prime + 2.75-4.75% (variable), terms 5-25 years
- SBA 504 loans: Fixed rate (~5-6%), terms 10-20 years for real estate/equipment
- Conventional bank loans: 6-12% for established businesses, 12-25% for newer businesses
- Equipment financing: 5-10% APR, terms 3-7 years
- Business lines of credit: Prime + 1-5% (variable), interest-only on balance
- Merchant cash advances: 1.2-1.5 factor rate (effectively 20-50%+ APR — avoid)
- Online alternative lenders: 10-30%+ APR, shorter terms
Always compare APR, not interest rate — APR includes fees and is the true cost of borrowing.
Common mistakes to avoid
Mistake 1: Comparing interest rates instead of APRs. APR includes origination fees, closing costs, and other charges. A 7% rate with 3% in fees has a higher APR than an 8% rate with no fees. Always compare APRs.
Mistake 2: Ignoring prepayment penalties. Some loans charge fees for early repayment. If you expect to repay early (sale of business, refinancing), confirm there's no prepayment penalty.
Mistake 3: Choosing a longer term just for lower payments. A 7-year term sounds more comfortable than 5 years, but it can cost $5,000+ more in interest. Only choose longer terms if cash flow genuinely requires it.
Mistake 4: Borrowing more than needed. Banks often approve more than you request. Borrowing extra "just in case" means paying interest on money you don't need. Borrow exactly what your project requires.
Mistake 5: Not modeling the impact on cash flow. A $1,000/month payment sounds manageable until your slow season hits. Model loan payments against your worst-month cash flow, not your average.
When to use this calculator
Use this calculator before applying for any business loan. Test multiple scenarios: different loan amounts, terms, and rates. Compare the monthly payment to your free cash flow (operating cash flow minus owner distributions). If payments consume more than 30% of free cash flow, you're over-leveraged.
For existing loans, use the calculator to evaluate refinancing opportunities. When interest rates drop 1-2%, refinancing can save thousands — but only if the savings exceed closing costs. Use the calculator to model both scenarios.
For prepayment decisions, model how extra payments affect total interest. An extra $100/month on a 30-year mortgage can save 5+ years of payments. The calculator shows the trade-off.
Related metrics and alternatives
Interest-only loan calculator: For loans where you pay only interest for a period, then principal + interest. Common in real estate and bridge financing.
Line of credit calculator: For revolving credit where you pay interest only on the outstanding balance. Better for short-term working capital than for fixed purchases.
Lease vs buy calculator: Compares leasing equipment to buying it with a loan. Useful for vehicle and equipment decisions.
Refinance calculator: Compares your current loan to a new loan with different terms, factoring in closing costs.
How to interpret the results
Monthly payment > 30% of free cash flow: Over-leveraged. Difficulty meeting payments if revenue drops. Consider smaller loan, longer term, or deferring purchase.
Total interest > 50% of principal: Long-term loan with high rate. Consider shorter term or refinancing when rates improve. The loan is consuming too much capital in interest.
APR > 15%: High-cost financing typical of alternative lenders. Consider whether the investment really generates enough return to justify the cost. Often a sign of distress borrowing.
APR > 30%: Predatory territory (merchant cash advances, some online lenders). Avoid unless facing immediate existential threat — and even then, explore alternatives first.