HELOC Calculator

A home equity line of credit (HELOC) lets you borrow against the equity in your home — the difference between its value and what you owe on the first mortgage. It is revolving credit, like a credit card secured by your house: you draw what you need during the draw period and pay it back (potentially repeatedly) over time.

Enter your home value, current mortgage balance, and the lender’s combined loan-to-value cap above. The calculator computes the largest line you could qualify for, the interest-only payment during the draw period (the full-draw worst case), and the amortizing payment once you enter repayment. Everything runs in your browser — your numbers are never uploaded.

How HELOC limits are set

Lenders cap a HELOC using combined loan-to-value (CLTV) — your first mortgage balance plus the HELOC, as a percentage of the home’s value. A common ceiling is 80% CLTV, though some lenders go to 85%. The credit limit is whatever headroom is left under that ceiling.

available equity = home value − mortgage balance
max credit limit = home value × CLTV % − mortgage balance
e.g. a $400k home with a $200k mortgage at 80% CLTV → $120k limit

Draw period vs. repayment period

A HELOC has two phases. During the draw period (often 10 years) you can borrow and reborrow up to the limit, and most lenders require only interest payments on the amount drawn. During the repayment period (often 20 years) the line is closed and the outstanding balance amortizes — you pay principal and interest in fixed payments until it is zero.

The interest-only payment shown here assumes you draw the full line, which is the worst case for the draw period. If you draw less, your interest payment is proportionally lower.

HELOC vs. cash-out refinance vs. home equity loan

A HELOC is revolving and variable: you pay interest only on what you draw, and the rate usually moves with the prime rate. A home equity loan (a second mortgage) is a fixed lump sum with a fixed rate and fixed payments. A cash-out refinance replaces your entire first mortgage with a larger one and gives you the difference in cash — it makes sense when first-mortgage rates have fallen, but resets your loan term. For investors recycling capital out of a property, the BRRRR calculator models that cash-out-refi path.

What HELOCs cost — and the risks

HELOC rates are variable, so payments rise when rates rise. Because the line is secured by your home, defaulting can mean foreclosure. Most HELOCs also have a draw period that ends — when it does, the balance must be repaid (amortized), which can cause a payment shock if you have drawn heavily. Borrowing against equity to invest amplifies both upside and downside; treat the repayment payment here as the number you must be able to carry indefinitely.

Frequently asked questions

How much can I borrow on a HELOC?

Typically up to 80–85% of your home’s value, minus what you owe on the first mortgage. On a $400,000 home with a $200,000 mortgage at an 80% CLTV cap, the maximum line is $400,000 × 0.80 − $200,000 = $120,000. The calculator above computes it for your numbers and chosen CLTV.

What is the difference between CLTV and LTV?

LTV (loan-to-value) is one loan against the value. CLTV (combined loan-to-value) adds every loan together. A HELOC is a second lien, so lenders use CLTV — first mortgage plus HELOC — to decide the limit. HLV (home equity line of value) is the same idea under another name some lenders use.

Is a HELOC interest-only forever?

No. During the draw period (often 10 years) most lenders require only interest on the amount drawn. After that, the repayment period (often 20 years) begins and the balance amortizes into fixed principal-and-interest payments. Drawing the full line maximizes the interest-only payment shown above.

Are HELOC rates fixed or variable?

Almost always variable, usually tied to the prime rate plus a margin set by the lender. That means the payment can rise if rates rise. Some lenders offer the option to convert part of the balance to a fixed rate; check the terms before relying on a rate.

Does this calculator upload my data?

No. Every calculation runs locally in your browser. The inputs never leave your device — confirm it in your browser’s network tab while editing the fields.