Finance

Line of Credit Interest Calculator

Find the interest cost on a revolving line of credit based on the drawn balance.


Line of Credit Interest Calculator

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A revolving line of credit charges interest only on what’s actually drawn, unlike a term loan with a fixed original principal.

How it works

The drawn balance times the monthly rate (annual rate divided by 12) gives the monthly interest. Multiplying by the number of months the balance is held gives the total interest cost over that period.

What this does not include

This assumes a constant drawn balance for simplicity — a real revolving line typically fluctuates as funds are drawn and repaid, meaning actual interest would need to be calculated against the changing balance each month rather than a single flat figure.

How to use this calculator

  1. Enter the drawn balance, annual interest rate, and months outstanding.

Frequently asked questions

How is a line of credit different from a term loan?

A term loan disburses a fixed amount upfront with a set repayment schedule; a line of credit can be drawn, repaid, and redrawn repeatedly up to a credit limit, with interest charged only on the outstanding balance.

Does paying down the balance early reduce interest?

Yes — since interest accrues on the outstanding balance, any early repayment reduces the balance interest is calculated against going forward, unlike some fixed-term loans with prepayment penalties.

Is a business line of credit the same as a HELOC?

No — a HELOC is specifically secured by home equity; a business line of credit may be secured by business assets or unsecured entirely, with different qualification and rate structures.

Important: This is general information, not financial advice. Figures are estimates, and your lender or provider decides the real numbers. Check with a qualified adviser before acting on them.

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Written by

M. Whitfield

Personal finance writer

M. Whitfield writes the personal finance calculators, covering loans, mortgages, savings, tax and investment maths. The focus is on showing exactly which number goes into a formula and which assumptions a result depends on, so readers can tell when a figure applies to their situation and when it does not. Every finance page states what it does not account for as plainly as what it does.

Reviewed by

A. Whitfield-Reyes

Calculator reviewer — finance

A. Whitfield-Reyes reviews the finance calculators, checking compounding conventions, rate-period alignment, and whether each page is explicit about the costs and tax treatment it leaves out. Financial results are easy to state with false precision, so review focuses on whether the page makes its assumptions visible to a reader who is not looking for them.

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