Quick answer
During the draw period the payment is interest-only: balance × rate ÷ 12. A $50,000 HELOC at 8% costs $333.33 a month for 10 years, then $418.22 a month over a 20-year repayment, totalling $90,372.81 of interest.
Enter the balance drawn, rate, draw period and repayment period. The calculator returns both payments and the total interest.
Related tools: Auto Loan Calculator: Monthly car payment after down payment and trade-in. Amortization Calculator: Full amortization schedule with optional extra monthly payments. Loan Calculator: Estimate your monthly loan payment, total interest and total cost.
How to use the HELOC Calculator
- Enter balance drawn ($) (above 0).
- Enter interest rate (%) (between 0 and 100).
- Enter draw period (years) (between 0 and 30). It starts at 10.
- Enter repayment period (years) (between 0 and 30). It starts at 20.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Balance drawn | A number, in $ | > 0 |
| Interest rate | A number, in % | ≥ 0, ≤ 100 |
| Draw period | A number, in years | ≥ 0, ≤ 30, starts at 10 |
| Repayment period | A number, in years | > 0, ≤ 30, starts at 20 |
Formula and method
Formula
draw payment = balance × rate ÷ 12; repayment payment = standard amortizing payment on the balance
IEEE-754 double precision; money shown to cents, rates to 4 decimals. Results are estimates, not financial advice.
Assumes a constant balance and a fixed rate; real lines are usually variable-rate.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Balance drawn = 50000; Interest rate = 8; Draw period = 10; Repayment period = 20.
| Result | Value |
|---|---|
| Interest-only payment (draw period) | $333.33 |
| Payment during repayment | $418.22 |
| Total interest | $90,372.81 |
Example 2
Inputs: Balance drawn = 20000; Interest rate = 6.5; Draw period = 5; Repayment period = 15.
| Result | Value |
|---|---|
| Interest-only payment (draw period) | $108.33 |
| Payment during repayment | $174.22 |
| Total interest | $17,859.87 |
The first line is the headline result (interest-only payment (draw period)). Below it the hELOC Calculator lists payment during repayment and total interest, which describe the same case from other angles. IEEE-754 double precision; money shown to cents, rates to 4 decimals. Results are estimates, not financial advice.
Payment shock
When the draw period ends, principal repayment begins and the payment rises from $333.33 to $418.22. Rates on HELOCs are usually variable; this calculation uses a fixed rate, so actual payments will change.
Your home is the collateral
A HELOC is secured by your home, so missed payments risk foreclosure. Compare the rate and fees with alternatives such as a home equity loan. The estimate excludes fees and further draws.
How the result changes with balance drawn
Holding every other input at the first worked example, this table changes only balance drawn. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Balance drawn | Interest-only payment (draw period) | Payment during repayment | Total interest |
|---|---|---|---|
| 25000 | $166.67 | $209.11 | $45,186.40 |
| 50000 | $333.33 | $418.22 | $90,372.81 |
| 100000 | $666.67 | $836.44 | $180,745.62 |
| 200000 | $1,333.33 | $1,672.88 | $361,491.23 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Balance drawn: entering "0" shows "Balance drawn must be greater than 0." beside that field and no result.
- Repayment period: entering "0" shows "Repayment period must be greater than 0." beside that field and no result.
Choosing between the HELOC Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Auto Loan Calculator](/finance/auto-loan-calculator/) | vehicle price, down payment and interest rate | Monthly payment |
| [Amortization Calculator](/finance/amortization-calculator/) | loan amount, interest rate and term | Monthly payment |
| [Loan Calculator](/finance/loan-calculator/) | loan amount, interest rate and term | Monthly payment |
| [Interest Rate Calculator](/finance/interest-rate-calculator/) | loan amount, monthly payment and term | Interest rate (APR) |
| [APR Calculator](/finance/apr-calculator/) | loan amount, upfront fees and note rate | APR |
Background: loans and mortgages
The interest rate is the cost of borrowing the principal; the APR also folds in certain fees, so a lower rate with high fees can have a worse APR. These calculators use the rate you enter and do not add fees, insurance or taxes, so add fees to the principal if you want to include them.
A fixed-rate loan is paid in equal instalments, early ones mostly interest. Extra payments go straight to principal, which shortens the loan and cuts interest; adjustable rates, escrow changes and prepayment penalties are not modelled.
Assumptions and limitations
- Fixed-rate simplification
Results are estimates for planning, not financial advice. Lender terms, fees, taxes and rounding rules can change real figures, so confirm important numbers with your lender or a licensed adviser.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for balance drawn and repayment period to confirm this.
Frequently asked questions
What is a draw period?
The time you can borrow, often 10 years.
Is the interest deductible?
Only in some cases, as tax rules change.
Is a HELOC fixed or variable?
Mostly variable: the rate is tied to a benchmark, so payments can rise, though some lenders let you fix part of the balance.
What does the HELOC Calculator calculate?
Interest-only draw-period payment and the repayment-period payment of a home equity line. It returns Interest-only payment (draw period), Payment during repayment and Total interest.
What formula does the HELOC Calculator use?
draw payment = balance × rate ÷ 12; repayment payment = standard amortizing payment on the balance. Assumes a constant balance and a fixed rate; real lines are usually variable-rate.
What do I need to enter in the hELOC Calculator?
You enter Balance drawn ($), Interest rate (%), Draw period (years) and Repayment period (years).
How is the result rounded or limited?
IEEE-754 double precision; money shown to cents, rates to 4 decimals. Results are estimates, not financial advice. Fixed-rate simplification.
What is an example of a hELOC result?
With balance drawn 50000, interest rate 8, draw period 10 and repayment period 20, the interest-only payment (draw period) is $333.33.
Can I rely on this calculator for a decision?
Results are estimates for planning, not financial advice. Lender terms, fees, taxes and rounding rules can change real figures, so confirm important numbers with your lender or a licensed adviser. For this calculator in particular: Fixed-rate simplification.
Related calculators
- Auto Loan Calculator — Monthly car payment after down payment and trade-in.
- Amortization Calculator — Full amortization schedule with optional extra monthly payments.
- Loan Calculator — Estimate your monthly loan payment, total interest and total cost.
- Interest Rate Calculator — Annual interest rate implied by a loan amount, payment and term.
- APR Calculator — Annual percentage rate of a loan once upfront fees are counted.
- Cash Back or Low Interest Calculator — Compare a cash rebate with a lower financing rate on a purchase.
Sources
- Standard time-value-of-money relations (e.g. Brealey, Myers & Allen, Principles of Corporate Finance)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.