When you want to tap equity, lenders do not let you borrow against the full amount. They limit borrowing using combined loan-to-value, or CLTV — a ratio that measures how much of your home’s value is already, or would be, financed by all loans secured against it. Understanding CLTV explains why the amount you can access is usually less than your total equity. This article explains the formula so you can estimate a figure; it is educational and not a recommendation to borrow.
Lenders cap total borrowing against a home at a share of its value (its "combined loan-to-value" limit, often around 80–85%). This is a rough estimate — your income, credit, and the specific lender all affect the real amount.
The formula. CLTV is the total of every loan secured by the home divided by the home’s value:
CLTV = (all loans secured by the home) ÷ home value
The “all loans” part is what makes it combined — it counts your existing first mortgage plus any new second mortgage (a HELOC or home equity loan) you are adding. Lenders set a maximum CLTV, commonly around 80–85%, though it varies by lender, loan type, and property (investment properties are often capped lower).
From the cap to a tappable-equity estimate. Rearranging the cap gives an estimate of how much you could borrow:
Tappable equity ≈ home value × max CLTV − existing balance
In plain terms: take a percentage of your home’s value (the cap), then subtract what you still owe. Whatever is left is roughly what a lender might let you access. If your existing balance is already above the cap, the tappable figure is zero.
Note that this is different from your total equity (home value − mortgage balance). Total equity uses 100% of value; tappable equity uses only the capped percentage — so the amount you can borrow is always less than the equity you have.
Suppose a home is worth $500,000, the owner owes $300,000, and the lender’s maximum CLTV is 85%. Total equity = $500,000 − $300,000 = $200,000. Maximum total lending allowed = $500,000 × 85% = $425,000. Tappable equity ≈ $425,000 − $300,000 = $125,000. So even though the owner has $200,000 of equity, a lender at an 85% CLTV cap might let them borrow only about $125,000 more. Change the cap to 80% and the tappable figure drops to $100,000; a higher existing balance would shrink it further.
A few things affect the real number:
Qualifying for the full tappable amount also depends on income, credit, and other underwriting factors — CLTV is a ceiling, not a guarantee.
CLTV is the ratio lenders use to cap total borrowing against a home: all secured loans divided by home value, held under a maximum (often around 80–85%). It is why the amount you can tap is always less than your total equity — tappable equity ≈ home value × max CLTV − existing balance. Knowing the formula lets you sanity-check any figure you are shown. It does not tell you whether tapping equity is wise; that depends on your full picture, and every option here is secured by your home.