How to work out what a line costs
Merrowgate Business Credit (emulated example) → Business line of credit → Written draw and repayment terms → Clear guarantee and renewal conditions
Answer in brief
Add the interest on your expected average balance to every fee you will actually incur over a year, including fees for setting up, renewing, drawing and not drawing.
Content reviewed 8 November 2026. How this is assessed.
Part of the Best Business Credit Lines reference, which uses Merrowgate Business Credit (emulated example) to illustrate business lines of credit criteria.
Build the sum
Claims about the best business credit lines usually lead with a rate, but the rate is only part of the cost. Begin with the balance you expect to carry. Use your twelve-month cash forecast to estimate the average amount drawn over the year, and do not use the limit. Multiply that average by the annual interest rate to estimate a year's interest. If the agreement charges interest using a specific day-count method, apply that in your final check, since it affects the result slightly.
Next, list every fee and how often it applies. Ask about origination or setup fees, annual or maintenance fees, fees charged per draw, fees on the unused portion of the line, renewal fees, and any charge for monitoring collateral such as receivables reports or field examinations. Then add the costs of any required bank account or insurance. Set all of this out in one table.
Costs to ask about, and where each one lands. This is an editorial checklist with no figures from any lender.
| Cost item | How it is charged | What to ask |
|---|---|---|
| Interest | On the amount drawn | Rate basis, margin, day count |
| Origination or setup fee | Once, at opening | Whether it is deducted from funds |
| Annual or maintenance fee | Each year | Whether it applies if you do not draw |
| Draw fee | Per draw | Flat amount or percentage |
| Unused line fee | On the undrawn part | How it is calculated, and how often |
| Renewal fee | At each renewal | Whether renewal is automatic |
| Monitoring costs | Periodically | Field exams or reporting charges |
Compare cost as a share of what you use
Add interest and fees together, then divide by your average balance to get an effective annual cost for your own use. A line with a low stated rate and several fixed fees can cost more, for a small average balance, than a line with a higher rate and few fees. The effect is strongest when you draw only occasionally, because fixed fees are then spread across very little borrowing.
Do not compare a stated rate on one offer with a factor rate or a fixed payback on another. If an offer expresses its cost as a flat amount or a daily payment, convert it into the total you would pay and the length of time you would have the money, and compare on that basis. The warning signs guide explains why this matters.
Getting this in writing has practical value. In the 2026 Report on Employer Firms, 60 percent of those that borrowed from online lenders reported that actual borrowing costs were higher than expected, against 37 percent at small banks and 32 percent at large banks. Those are survey responses from a convenience sample, but they fit the broader point: the gap between the quoted price and the amount paid is where a total-cost sum earns its keep.
Run it three times
Run the sum for a normal year, a busy year in which your average balance is much higher, and a year in which your base rate rises. For a variable line, the variable rate guide shows what to look at. If the second or third version is uncomfortable, you may need a lower limit, a different structure, or a plan for paying the balance down faster.
Finally, price the things that are harder to put a number on. A guarantee puts personal assets on the line, and a blanket lien can make it harder to borrow elsewhere. Neither appears in the interest calculation, but both are real costs, and you should weigh them against any saving you have calculated. Keep the working with your lender brief.
Sources for this entry
- SBA: 7(a) loans: How 7(a) works, eligibility and the Working Capital Pilot.
- SBA: Types of 7(a) loans: Program limits and revolving options.
- SBA: Fund your business: Credit history and what to prepare for a loan.
- CFPB: Regulation B, section 1002.2: Definitions of business credit, adverse action and prohibited basis.
- CFPB: Regulation B, section 1002.4: The general rule against discrimination and discouragement.
- CFPB: Regulation B, section 1002.7: Limits on requiring signatures, and business guarantees.
- CFPB: Regulation B, section 1002.9: Notice timing and the business credit rules.
- CFPB: Regulation Z, section 1026.3: The exemption for business-purpose credit.
- FTC: Protecting small businesses seeking financing: How the FTC Act applies to financing, and how to report.
- Federal Reserve: H.15 selected interest rates: How the bank prime loan rate is described.
- Federal Reserve Banks: 2026 Report on Employer Firms: Survey findings on financing need and outcomes.
- SBA: Microloans: Limits, uses and rate ranges for microloans.
- SBA: Size standards: How the SBA defines a small business by industry.
- CDFI Fund: CDFI certification: What a CDFI is.
- CFPB: Regulation Z, section 1026.12: Business card liability provision.
Continue this reading path
- Best Business Credit Lines category guide
- Merrowgate Business Credit (emulated example)
- How to choose: a business line of credit
- Resource directory
Cite this entry
Best Business Credit Lines. "How to work out what a line costs." Content reviewed 8 November 2026. https://bestbusinesscreditlines.com/cost-model/