A business line of credit calculator estimates two things: the monthly (or weekly) payment on the amount you draw, and the credit limit a lender is likely to approve based on your revenue and deposit history. Unlike a term loan, a line of credit only charges interest on the balance you actually use, so the calculation starts with your outstanding draw — not your full limit. To run the numbers you need four inputs: the amount drawn, the interest rate (or factor), the repayment term, and any per-draw or maintenance fees. This page walks through the formulas, shows fully worked examples with rounded figures, and explains how lenders decide your limit — including a revenue-based marketplace option for owners who qualify on bank deposits rather than credit score.
Key takeaways
- A line of credit charges interest only on the amount you draw, not your full limit — so calculations start with your outstanding balance.
- Rough monthly interest on a stable balance = balance x (annual rate / 12); fixed-installment draws use the standard amortizing payment formula.
- Fees beyond interest — origination, per-draw, maintenance, and inactivity — can materially change your true cost and are often omitted from simple estimates.
- Revenue-focused lenders often size limits as a multiple of average monthly revenue; steady deposits matter more than a single strong month.
- A revenue-based advance is priced with a flat factor rate (funded amount x factor = total repaid), so early payoff does not save money the way a line does.
- A revenue-based marketplace leans on bank deposits and revenue, accepts FICO around 500+, starts near $10,000, and often funds in 24-48 hours — never guaranteed.
- Example figures on this page are rounded and illustrative; your actual rate, limit, and payment depend on your profile and lender.
How a Line of Credit Calculation Actually Works
A line of credit is revolving, which means the math is different from a fixed installment loan. Three ideas drive every estimate:
- You pay interest only on the drawn balance. If your limit is $50,000 but you draw $15,000, interest accrues on the $15,000 — not the limit. Undrawn credit usually costs nothing beyond a possible maintenance or inactivity fee.
- Interest accrues on the outstanding balance over time. As you repay principal, the balance falls and each subsequent interest charge is smaller. This is why a revolving balance costs less than a same-size term loan held to maturity.
- The rate can be quoted as APR or as a simple/factor cost. Banks quote an annual percentage rate; many online and revenue-based providers quote a flat fee or factor rate, which behaves very differently. Converting between the two is essential before you compare offers.
For a rough monthly interest figure on a stable balance, the formula is straightforward:
Monthly interest = Outstanding balance × (Annual rate ÷ 12)
For a drawn amount you plan to repay in fixed installments over a set term, use the standard amortizing payment formula, where r is the periodic rate and n is the number of payments:
Payment = P × [ r × (1 + r)n ] ÷ [ (1 + r)n − 1 ]
Worked Example: Estimating Your Payment
Suppose you draw $25,000 against a line of credit, agree to a 12-month repayment on that draw, and the rate works out to an 18% APR (1.5% per month). The numbers below are rounded and shown for illustration only — your actual quote will vary by lender and profile.
| Input | Example value |
|---|---|
| Amount drawn | $25,000 (for example) |
| Annual rate (APR) | 18% (for example) |
| Repayment term on the draw | 12 months |
| Estimated monthly payment | ~$2,292 (for example) |
| Total repaid | ~$27,505 (for example) |
| Total interest | ~$2,505 (for example) |
Notice the interest is far less than 18% of $25,000 ($4,500). That is because you are only borrowing the full amount for the first month; as you repay, the balance shrinks and interest is charged on less each period. If you drew the same amount but repaid over 6 months instead of 12, the monthly payment rises to roughly $4,373 (for example) but total interest falls to about $1,235 — a shorter term costs more per payment and less overall.
How Interest Accrues on a Revolving Balance
Because you can draw and repay repeatedly, real-world interest rarely matches a clean amortization schedule. Interest is typically calculated on the average daily balance. Here is a simplified month where an owner draws twice and makes one payment, at an assumed 18% APR (a daily rate of about 0.0493%).
| Day range | Balance | Event | Interest for the period (for example) |
|---|---|---|---|
| Days 1–10 | $10,000 | Initial draw | ~$49 |
| Days 11–20 | $18,000 | Second draw of $8,000 | ~$89 |
| Days 21–30 | $13,000 | $5,000 payment applied | ~$64 |
| Estimated interest for the month | ~$202 (for example) | ||
The takeaways: repaying earlier in a cycle reduces the balance interest is charged on, and drawing only what you need — when you need it — is the single biggest lever on cost. A calculator that ignores draw timing will overstate what a disciplined borrower actually pays.
Fees That Change Your True Cost
The rate is only part of the picture. Line-of-credit products can carry several fees that a bare interest calculation misses. Typical ranges are shown below for illustration; always confirm the exact schedule in your agreement.
| Fee type | When it applies | Typical range (for example) |
|---|---|---|
| Origination / setup fee | Once, when the line opens | 0%–3% of the limit |
| Draw fee | Each time you pull funds | 1%–3% of the draw |
| Maintenance / monthly fee | Ongoing, whether or not you draw | $0–$50 per month |
| Inactivity fee | If the line sits unused for a set period | Varies by lender |
| Late payment fee | Missed or partial payment | Flat fee or % of payment |
To find your effective cost, add draw and maintenance fees to interest, then divide by the amount you actually used. A 1% rate with a 3% draw fee on frequent small draws can cost more than a slightly higher rate with no draw fee — which is why comparing APR alone can mislead.
How Lenders Decide Your Credit Limit
Most owners searching for a calculator also want to know how large a limit they can get. Traditional banks weight your credit score, time in business, and financial statements heavily. Revenue-focused providers weight your deposits instead. A common rough guide is that a limit is offered in proportion to monthly revenue:
Estimated limit ≈ Average monthly revenue × a multiple set by the lender
| Average monthly revenue | Illustrative limit range (for example) |
|---|---|
| $20,000 | ~$10,000–$20,000 |
| $50,000 | ~$25,000–$50,000 |
| $100,000 | ~$50,000–$100,000 |
These figures are directional examples, not offers. The stronger and steadier your bank deposits, the higher the multiple a lender is comfortable extending. Consistent revenue matters more than a single big month, because approval models look for reliable cash flow to repay against.
Line of Credit vs. a Revenue-Based Advance
If your credit score keeps you from a bank line, a revenue-based advance from a marketplace can be a faster path to working capital. It is priced with a factor rate rather than an APR, so the two products calculate differently.
| Feature | Business line of credit | Revenue-based advance (marketplace) |
|---|---|---|
| Pricing method | Interest rate / APR on balance | Flat factor rate on the funded amount |
| Approval leans on | Credit score, time in business, statements | Bank-deposit history and monthly revenue |
| Typical minimum FICO | Often 600+ | 500+ (for example) |
| Minimum amount | Varies | ~$10,000 (for example) |
| Funding speed | Days to weeks | Often 24–48 hours |
| Reusable | Yes, revolving | No, per-advance |
To read a factor rate, multiply the funded amount by the factor: $25,000 at a 1.25 factor means you repay $31,250 (for example), regardless of how quickly you pay it off. Because there is no interest saved by early payoff, a factor-rate product favors owners who value speed and flexible approval over the lowest possible cost. Approval is never guaranteed, but a marketplace can shop multiple funders at once, which improves your odds when bank criteria are tight.
Using the Numbers to Choose the Right Option
Run your own scenario before you apply. Start with the amount you realistically need to draw in the next 90 days, not the largest limit you could qualify for — you pay for what you use, so an oversized line mostly adds fees. Estimate the payment at your quoted rate, add every applicable fee, and compare that total against what the capital will earn or save. If a $25,000 draw funds inventory that returns $35,000, the financing cost is easy to justify; if the margin is thin, a shorter term or a smaller draw protects your cash flow.
For owners who qualify on revenue rather than credit, a revenue-based marketplace is worth a quote alongside any bank line. Because approval leans on deposit history and monthly revenue and funding is often 24–48 hours, it can bridge a gap a bank timeline cannot — provided you have modeled the fixed repayment first and confirmed it fits your cycle.
Frequently asked questions
How do I calculate the payment on a business line of credit?
Start with the amount you actually drew, not your full limit — a line of credit charges interest only on the outstanding balance. For a draw you plan to repay in fixed installments, apply the standard amortizing payment formula using the periodic rate and number of payments. For a rough monthly interest figure on a stable balance, multiply the balance by the annual rate divided by 12. Then add any draw or maintenance fees to get your true cost.
Why is the interest less than the rate times my full limit?
Two reasons. First, you only pay interest on what you draw, so an unused portion of your limit costs nothing beyond a possible maintenance fee. Second, as you repay principal the balance falls, and each later interest charge is calculated on that smaller balance. A revolving balance repaid over time therefore costs noticeably less than the headline rate applied to the full amount.
What inputs does a line of credit calculator need?
At minimum: the amount you plan to draw, the interest rate or factor, the repayment term, and the payment frequency. To estimate fees and true cost, add any origination, per-draw, and monthly maintenance charges. To estimate your likely limit rather than a payment, you also supply average monthly revenue, time in business, and credit score.
How do lenders decide my credit limit?
Banks weight credit score, time in business, and financial statements. Revenue-focused providers weight your bank-deposit history and monthly revenue, often offering a limit as a multiple of average monthly revenue. Steady, reliable deposits matter more than one strong month, because approval models look for consistent cash flow to repay against. Any limit estimate is directional until a lender reviews your actual statements.
What's the difference between a line of credit and a revenue-based advance?
A line of credit is revolving and priced with an interest rate on your outstanding balance, so early repayment saves interest. A revenue-based advance is a lump sum priced with a flat factor rate — you repay a fixed total regardless of payoff speed. Advances lean on deposit history rather than credit score, often accept a FICO around 500 or higher, start near $10,000, and can fund in 24 to 48 hours, but they are not reusable like a line.
How do I convert a factor rate to compare it with an APR?
Multiply the funded amount by the factor rate to get the total repayment — $25,000 at a 1.25 factor is $31,250 (for example). Because that cost is fixed and does not shrink with early payoff, a factor rate is not directly the same as an APR. To approximate an APR you would annualize the cost over the expected repayment period, but the simplest honest comparison is total dollars repaid on each option for the amount and timeline you actually plan to use.
Can I get approved with a low credit score?
Possibly. Bank lines of credit often want a score around 600 or higher, but revenue-based marketplace funders emphasize bank deposits and monthly revenue and may work with a FICO of 500 or above (for example). A marketplace can shop several funders at once, which improves your odds when bank criteria are tight. Approval is never guaranteed, and you should model the fixed repayment against your cash flow before applying.
How can I reduce what a line of credit costs me?
Draw only what you need and only when you need it, since interest accrues on the drawn balance. Repay earlier in each cycle to lower the average daily balance interest is charged on. Choose a shorter term if your cash flow allows — it raises the payment but cuts total interest. Finally, weigh the rate together with draw and maintenance fees, because frequent small draws under a per-draw fee can cost more than a slightly higher rate with none.
