Loan payments
For a fully amortizing loan, the monthly payment is P × r ÷ (1 − (1 + r)−n), where P is the amount borrowed, r is the annual rate divided by 12, and n is the number of monthly payments. Total interest is the payment times n, minus P. At a rate of zero the payment is P divided by n.
Debt service coverage ratio (DSCR)
DSCR equals annual net operating income divided by annual debt service (twelve monthly payments). The 1.25x level we mention is a common lender benchmark, not a rule; each lender sets its own.
SBA fees and rules
The SBA calculators follow SBA's published fee notices for fiscal year 2027, which cover loans approved October 1, 2026 through September 30, 2027: Information Notice 5000-881797 for 7(a) and 5000-881796 for 504. SBA revises these every fiscal year, and the tool says so wherever it shows a fee.
- 7(a) upfront fee. The tier is chosen by the gross loan amount and the percentage applies to the guaranteed portion: 2% for loans of $150,000 or less, 3% for $150,001 to $700,000, and for larger loans 3.5% of the guaranteed portion up to $1,000,000 plus 3.75% of the portion above $1,000,000. Manufacturers, listed food-supply-chain businesses and rural businesses pay 0% on loans of $700,000 or less.
- Guarantee. 85% up to $150,000 and 75% above for standard loans; 50% for SBA Express.
- Annual service fee. 0.55% of the guaranteed balance for 7(a). SBA charges it to the lender and does not allow it to be passed to the borrower, so we show it for information only.
- Maximum spread. For variable-rate 7(a) loans: base rate plus 6.5% up to $50,000, 6.0% to $250,000, 4.5% to $350,000, and 3.0% above $350,000.
- 504 structure and fees. The bank holds about 50%, the CDC up to 40% and the borrower 10%, with 5 more points of equity for a new business and 5 more for a special-purpose property (which lowers the CDC share). Fees are 0.50% upfront and 0.203% annually on the SBA-backed debenture. The tool assumes the bank and CDC portions share one term and that the debenture is the CDC share of the project.
The tool does not model the 0.25% fee on loans of 12 months or less, the rule that combines loans approved within 90 days of each other, the $0 fee on SBA Express loans to veteran-owned businesses, CDC processing fees, or lender fees.
Line of credit
Monthly interest equals the average drawn balance times the annual rate divided by 12. The result adds any annual fee you enter. It does not simulate individual draws and repayments.
Equipment financing estimates
The equipment rate is a planning model, not a lender quote. We start from a base rate for each credit profile (excellent 7.5%, good 10%, fair 14%, weak 20%, poor 28%), add an adjustment for the equipment type (from −0.25 points for agricultural to +2.0 points for IT), add 1.5 points for used equipment, subtract half a point for a down payment of 20% or more, and add a point for a down payment under 5%. The result is kept near the range lenders and rate guides publish for that credit profile. Real offers also depend on time in business, cash flow, collateral and the lender.
Commercial real estate, down payment and lease tools
- Commercial real estate loan. The payment uses the amortization period you enter. If the loan term is shorter, the balance still owed at the end of the term is the balloon payment. Loan-to-value is the share of the price you borrow, and DSCR is net operating income divided by twelve payments.
- SBA down payment. A planning figure: 10% of project cost for a 7(a) startup or purchase of a business, and for a 504 loan 10% plus 5 points for a new business and 5 more for a special-purpose property. Lenders can ask for more, and the 7(a) expansion figure is the lender's decision.
- Equipment payment by term. The same estimated rate is applied at every term from 2 to 7 years, so the table shows how term alone changes the payment and total interest. Real lenders often charge more for longer terms.
- Lease versus loan. Compares financing cost only, with no tax effects. The loan payment follows the payment formula. The lease payment amortizes the price minus the present value of the equipment's end value at the lease rate. Net cost is cash paid minus the value of any equipment you keep.
Mortgage, affordability and refinance
- Mortgage. Principal and interest by the payment formula, plus property tax (home price times the tax rate, divided by 12) and insurance (annual premium divided by 12). When the down payment is under 20% it also adds private mortgage insurance, estimated as the loan amount times the PMI rate you enter, divided by 12. It excludes HOA dues.
- Affordability. The housing budget is the smaller of 28% of gross monthly income and 36% of gross monthly income minus other debts. We subtract insurance, then solve for the price at which principal and interest on the loan plus property tax equals what is left, assuming a 30-year loan.
- Refinance. Balance today is computed from your original loan, rate, term and years paid. We compare the monthly payment and remaining interest on the current loan with a new loan on that balance. Break-even in months is closing costs divided by monthly savings.
Where the reference data comes from
Only the rate strip and the News page load live reference data, from a file refreshed daily: the weekly 30-year, 15-year and refinance averages from Freddie Mac's Primary Mortgage Market Survey (these are survey averages, not quotes), the prime rate from the St. Louis Fed's DPRIME series, and headlines from the Federal Reserve, the Consumer Financial Protection Bureau and news searches on mortgage rates, small business lending, equipment finance and commercial real estate. We reject any prime-rate value that is not a plausible rate, so a failed download can never become a number in a calculator.
What we send, and what we do not
- There is no account or sign-in. The calculators make no network request with your numbers.
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Corrections
If a figure does not match your own arithmetic, or a formula here has drifted from what the tools do, send us a message with the page, the calculator and the inputs you used.