HELOC Calculator
LoanEstimate your available home equity, maximum HELOC limit, and monthly payments for both the draw period and repayment period in seconds, free online.
Monthly Payment by Phase
Draw Period
(Interest-Only)
(Interest-Only)
$0
/month
Repayment Period
(Amortizing)
(Amortizing)
$0
/month
Drawing $50,000 of $0 limit0%
Available Equity
$0
Total Interest (Repay.)
$0
What is a HELOC?
A HELOC Calculator estimates how much home equity you can borrow against and what your payments will look like across both phases of a Home Equity Line of Credit. A HELOC is a revolving credit line secured by your home — distinct from a fixed-amortization loan like a Mortgage Calculator scenario — that lets you draw funds as needed up to an approved limit, repay them, and draw again during an initial draw period, before transitioning into a structured repayment period.
Because a HELOC behaves so differently from a standard installment loan, modeling it requires tracking two distinct phases separately: the draw period, where payments are often interest-only on the amount actually borrowed, and the repayment period, where the outstanding balance is amortized into a fixed principal-and-interest payment over a set number of years. This calculator computes your available equity, your maximum HELOC limit based on your lender's combined loan-to-value (CLTV) cap, and estimated payments for both phases so you can see the full picture before applying.
How to use this HELOC calculator
- Enter your Home Value — the current estimated market value of your property.
- Enter your Existing Mortgage Balance — what you currently owe on your primary mortgage.
- Set the Max Combined LTV Allowed slider to match your lender's policy (commonly 80-85%).
- Enter the Amount You Plan to Draw — how much of the available HELOC limit you intend to actually use.
- Enter the Interest Rate (Variable) quoted by your lender, keeping in mind this can change over time.
- Set the Repayment Period in years to see the amortized payment once the draw period ends.
- Compare the draw-period and repayment-period payment estimates to make sure you can afford both phases, not just the lower introductory one.
Formula & Methodology
Available equity is calculated as: Equity = Home Value − Mortgage Balance Maximum HELOC limit applies the lender's CLTV cap: Max HELOC = (Home Value × Max CLTV%) − Mortgage Balance During the draw period, payments are interest-only on the drawn balance: Draw Payment = Drawn Amount × (Annual Rate ÷ 12 ÷ 100) During the repayment period, the balance amortizes using the standard loan formula: Repayment Payment = P × r × (1 + r)ⁿ ÷ [(1 + r)ⁿ − 1] Where P is the drawn principal, r is the monthly interest rate, and n is the number of months in the repayment term. Worked example: On a $400,000 home with a $200,000 existing mortgage and an 85% max CLTV, the available equity is $200,000, but the maximum HELOC limit is capped at (400,000 × 0.85) − 200,000 = $140,000. If you draw $50,000 at an 8.5% variable rate, the draw-period interest-only payment is roughly $354 per month. Once the 15-year repayment period begins on that same $50,000 balance, the fully amortized payment jumps to approximately $493 per month, with total interest of around $38,700 over the repayment term. Use a Down Payment Calculator if you're still deciding how much equity to build up before applying, or a Home Affordability Calculator to check your total housing debt capacity including the HELOC repayment estimate.
Frequently Asked Questions
A Home Equity Line of Credit (HELOC) is a revolving credit line secured by the equity in your home, similar in structure to a credit card but backed by real estate. Instead of receiving a lump sum like a traditional mortgage, you're approved for a maximum limit and can draw, repay, and redraw funds as needed during a set draw period. Most HELOCs carry a variable interest rate and are split into two distinct phases: a draw period and a repayment period.
A home equity loan gives you a fixed lump sum upfront with a fixed interest rate and a single amortization schedule, much like a standard [Mortgage Calculator](/mortgage-calculator/) scenario. A HELOC instead works like a credit line — you only pay interest on what you actually draw, and the rate is usually variable rather than fixed. This flexibility makes a HELOC better suited for ongoing or uncertain expenses, while a home equity loan or mortgage is better for one-time, known costs.
The draw period is the initial phase of a HELOC — typically 5 to 10 years — during which you can borrow against your credit line and often only need to make interest-only payments on the amount drawn. Once the draw period ends, the HELOC enters the repayment period, where you can no longer draw new funds and must repay the outstanding balance through fully amortizing principal-and-interest payments, usually over 10 to 20 years. This calculator models both phases separately because the payment amount typically jumps significantly when you transition from interest-only to amortizing payments.
Lenders calculate your available equity as your home's current market value minus your outstanding mortgage balance, then apply a maximum combined loan-to-value (CLTV) limit — commonly around 80-85% — to determine your HELOC limit. For example, on a $400,000 home with a $200,000 mortgage balance, you have $200,000 in equity, but your actual HELOC limit will be capped by the lender's CLTV rule rather than the full equity amount. Most lenders also require a minimum credit score and a manageable debt-to-income ratio before approving a HELOC.
Enter your home's current value, your existing mortgage balance, and the maximum combined LTV your lender allows, and the calculator computes your available equity and maximum HELOC limit. Then enter the amount you plan to draw, the variable interest rate, and your expected repayment term to see estimated payments for both the draw period (interest-only) and the repayment period (fully amortized). Adjust any slider to instantly see how the numbers change.
During the draw period, many HELOCs only require interest-only payments, which can make the monthly cost feel deceptively low relative to the amount borrowed. Once the repayment period begins, the lender requires you to pay down the principal as well, converting the loan into a standard amortizing payment over a shorter remaining term — often causing payments to double or more. This calculator shows both figures side by side specifically so this jump isn't a surprise.
Under current US tax law, HELOC interest is generally only deductible if the funds are used to buy, build, or substantially improve the home that secures the loan, and the combined mortgage debt stays within IRS limits. If the HELOC funds are used for other purposes — debt consolidation, tuition, or general expenses — the interest is typically not deductible. Consult a tax professional for guidance specific to your situation, since rules can change and depend on your overall mortgage debt.
Yes — because HELOC rates are usually variable and tied to an index like the prime rate, your interest rate (and therefore your payment) can rise or fall over the life of the credit line. Some lenders can also reduce your credit limit or freeze further draws if your home's value drops significantly or your financial situation changes. It's worth re-running this calculator periodically with updated rate assumptions to track how your potential payments might shift.
Combined loan-to-value is the total of your existing mortgage balance plus your HELOC limit, expressed as a percentage of your home's value. Lenders use a CLTV cap — commonly 80-85% — to limit their risk exposure, which means the more you already owe on your primary mortgage, the less room you have for a HELOC. This calculator lets you adjust the maximum CLTV percentage to match your specific lender's policy and see how it affects your available limit.
A HELOC adds a second, separate credit line on top of your existing mortgage, leaving your original mortgage rate and terms untouched — useful if your current mortgage rate is lower than today's market rate. A cash-out refinance, by contrast, replaces your entire mortgage with a new, larger one, which only makes sense if today's rates are competitive; you can compare this using a [Mortgage Refinance Calculator](/mortgage-refinance-calculator/). Run both scenarios to see which structure gives you the lower overall borrowing cost for your specific equity and rate situation.
Because a HELOC is secured by your home, failing to make payments during the repayment period can ultimately lead to foreclosure, just as with a primary mortgage. This makes it important to size your draw amount conservatively and to model the repayment-period payment — not just the lower draw-period payment — before committing to a large balance. Use a [Home Affordability Calculator](/home-affordability-calculator/) to sanity-check your overall housing debt load including the HELOC repayment estimate.
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