Estimates only Not a loan offer Not financial advice No live bank rates

HELOC Calculator — Interest & Payment Estimator

Got a HELOC quote on the kitchen table? Drop in home value, what’s left on the first mortgage, how much you’ve drawn, and the APR they gave you. You’ll get a rough interest-only bill for the draw years, then what repayment might look like once the line starts amortizing — plus a quick CLTV sanity check. We don’t pull live bank rates. You type the APR.

Starter numbers (change them): $400k home, $250k left on the mortgage, $25k drawn on a $75k line at 8.5% APR. It’s just a sketch so the fields aren’t empty.

HELOC inputs

Interest-only and EMI estimates use this balance.
Paste the APR from your lender quote — we never fetch live bank rates.

Rough context only (not a live feed): U.S. prime was commonly cited near 7.00% as of early Nov 2026; many HELOC quotes sit at prime + a margin. Your quote still wins.

Results

Draw-period interest-only payment

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Per month while interest-only · — months in draw sketch

Repayment EMI (fully amortizing)

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Per month after draw · — months

Sketch total interest (IO + amort)

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Draw IO total — · repayment interest — · assumes constant drawn balance, then full amort

CLTV (mortgage + drawn ÷ home value)

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Illustrative equity / credit room

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Against your max CLTV ceiling and remaining line — not a lender decision

What if your APR is higher?

Same balance and terms — we only bump the APR you typed by 0 / +1 / +2. Still not live bank rates.

APR shock APR used IO / mo Repay EMI / mo Δ vs your APR
Heads-up These are estimates for planning — not a loan offer, and not financial, tax, or legal advice. APR is whatever you type; we don’t show live bank rates. Real HELOC terms (variable rates, fees, floors, freezes) can differ. Talk with a licensed lender before you decide.

How this HELOC interest calculator works

Most lines feel like two chapters. During the draw years, a lot of lenders just want interest on what you’ve actually used. Later the payment usually flips to a fixed-term payoff that chips away at principal. Use the form above to sketch both. APR stays whatever you typed — no live rate feed here.

Draw-period interest-only

Monthly interest-only estimate = drawn balance × (APR ÷ 12). If your line is unused, interest is zero. Extra principal payments are not assumed.

Repayment fully amortizing EMI

We use the standard amortizing payment formula M = P × r × (1+r)n / ((1+r)n − 1), where P is the balance entering repayment, r is the monthly rate, and n is repayment months. That EMI is what many people mean when they search for a “HELOC interest calculator” or “HELOC payment calculator.”

CLTV and equity room

CLTV = (first mortgage + HELOC drawn) ÷ home value. The equity-room sketch applies your max CLTV percentage and remaining credit limit. Lenders apply their own rules; treat this as a planning aid only.

What this tool does not do

HELOC calculator FAQ

What is a HELOC interest calculator?

It’s a quick way to sketch two payments: interest-only while you’re still drawing, then a fully amortizing bill once repayment starts — using the balance, APR, and terms you type in.

How is HELOC interest calculated during the draw period?

Simple version: monthly interest ≈ drawn balance × (APR ÷ 12). Principal usually sits still unless you throw extra at it.

What happens in the HELOC repayment period?

After draw ends, a lot of HELOCs switch to fully amortizing payments. We use the standard EMI formula so both principal and interest get paid down over the repayment months you enter.

Does this site use live bank rates?

Nope. You enter the APR. We don’t run a rate board, and we don’t offer loans.

What is CLTV and why does it matter?

CLTV is first mortgage + HELOC balance, divided by home value. Lenders watch that ceiling when they size a line. Our “equity room” number is just a planning sketch.

Is this a loan offer or financial advice?

No. Educational estimates only — not an offer to lend, not a credit decision, and not personal financial, tax, or legal advice. Double-check with a licensed lender or advisor.

HELOC vs home equity loan — which calculator should I use?

HELOC tool = revolving line (draw, then repay). Home equity loan tool = one lump sum that amortizes from day one. Pick the product that matches your paperwork.

Will my real payment match this estimate?

Maybe not. Fees, variable rates, floors, freezes, taxes — lenders have their own knobs. Treat this as a planning sketch, not a closing figure.

Related tool

Home Equity Loan Calculator

Want a fixed second-mortgage payment instead of a revolving line? Same site, different product shape.