Line of Credit Calculator

A line of credit is flexible because you can draw, repay, and draw again up to an approved limit. That flexibility also makes payment planning harder than a fixed loan. This calculator estimates a payment per period for a revolving credit balance, applies a minimum-payment rule, simulates interest and payments across the selected term, and reports utilization. It can help with personal credit lines, business lines, and simplified HELOC-style planning.

Unlike a standard installment loan, a credit line has two numbers: the credit limit and the current balance. Interest is charged on the balance, not on the unused limit, but utilization still matters because it shows how much of the available line is already in use. If you need a fixed principal loan instead, compare the loan calculator or personal loan calculator. If the borrowing is tied to home equity, the HELOC payment calculator may be a more specific companion.

How to use this calculator

Enter the credit limit and current balance. The balance must be nonnegative and cannot be greater than the limit. Enter the annual percentage rate, payment term in months, and minimum payment percentage. Choose monthly or bi-weekly payments. If you expect to keep borrowing, enter additional draws per payment period. The calculator adds that draw before each period’s interest is computed.

The payment result is the greater of two amounts: the amortized payment needed to repay the starting balance over the scheduled periods, or the minimum-payment rule. The minimum rule is the entered percentage of the starting balance, with a $50 floor. Because additional draws do not recalculate the payment, repeated borrowing can leave a balance at the end of the schedule. That is not displayed as a separate result, so review the total interest and total payment as estimates rather than a guaranteed payoff plan.

Formula

Payment frequency determines periods per year:

$\text{payments per year} = 12 \text{ for monthly, or } 26 \text{ for bi-weekly}$

The periodic rate is:

$\text{periodic rate} = \frac{\text{annual rate}}{\text{payments per year}}$

Scheduled periods are:

$\text{periods} = \text{term months} \text{ for monthly payments}$

For bi-weekly payments, the calculator uses the ceiling of term months times 26 divided by 12. The amortized payment for the starting balance is:

$\text{amortized payment} = \text{balance} \times \frac{\text{periodic rate} \times (1 + \text{periodic rate})^{\text{periods}}}{(1 + \text{periodic rate})^{\text{periods}} - 1}$

The final payment per period is:

$\text{payment} = \max(\text{amortized payment}, \max(\text{balance} \times \text{minimum percent}, 50))$

Utilization is:

$\text{utilization} = \frac{\text{current balance}}{\text{credit limit}}$

Worked example

Use the default inputs: $10,000 credit limit, $5,000 current balance, 12.99 percent APR, 24 months, 3 percent minimum payment, no additional draws, and monthly payments. The utilization rate is 50.0 percent. The periodic rate is 12.99 percent divided by 12, or about 1.0825 percent per month. The amortized payment over 24 months is $237.69.

The minimum payment rule is the greater of 3 percent of $5,000, which is $150, and the $50 floor. Because $237.69 is higher than $150, the calculator uses $237.69 as the payment per period. Simulating 24 periods produces total interest of $704.46 and total payment of $5,704.46. With no additional draws, the balance is essentially paid off by the end of the schedule.

Revolving-credit context

The key difference between a line of credit and a fixed loan is control. You can borrow only what you need, repay, and borrow again without applying for a new loan each time. That can be useful for uneven expenses, seasonal business needs, home projects, or emergency liquidity. It can also encourage slow payoff if new draws keep arriving while the payment stays low.

This calculator intentionally models a simplified version. Many real credit lines use daily interest, variable APRs, draw and repayment phases, transaction fees, annual fees, or minimum payments based on interest plus a percentage of principal. Some lines are unsecured, while a HELOC is secured by the home. If your line is variable-rate, rerun the calculator at higher rates to see how much payment stress a reset could create. For a credit-card payoff problem with a revolving balance, the credit card payoff calculator is usually more appropriate.

Tips for using a line responsibly

• Keep utilization below the level that makes future draws uncomfortable.
• Separate planned draws from emergency capacity; do not spend the entire line just because it is available.
• Recalculate after every major draw, especially if the lender’s minimum payment is interest-heavy.
• Compare a fixed loan if the project has a known cost and you do not need repeated draws.
• Build the payment into the budget calculator before assuming the line is affordable.

Sources

• Consumer Financial Protection Bureau, Credit cards — consumer guidance on revolving credit concepts.
• Consumer Financial Protection Bureau, What is a loan? — general explanation of borrowing and repayment.
• Federal Reserve, Consumer Credit - G.19 — official consumer credit data context.