How is home equity calculated?

Home equity is simply the current market value of your home minus the outstanding balance on all mortgages secured against it. If your home is worth $400,000 and you owe $250,000, your equity is $150,000 (37.5%). Equity grows two ways: through principal paydown (your mortgage payments) and through home value appreciation. In early years of a mortgage, most of your payment goes toward interest — equity builds slowly at first and accelerates over time.

What is loan-to-value (LTV) ratio and why does it matter?

LTV is the ratio of your mortgage balance to your home's value, expressed as a percentage. Lenders use it to assess risk. Below 80% LTV you typically avoid PMI on a conventional loan. Below 80% you also qualify for the best HELOC rates. Most lenders require LTV below 85–90% to approve a HELOC or cash-out refinance. LTV above 90% makes borrowing against equity very difficult without special programs.

How much can I borrow against my home equity?

Most HELOC and home equity loan lenders allow a combined LTV (your first mortgage plus the new loan) of up to 85% of your home's value. So if your home is worth $500,000 and you owe $300,000, the maximum combined debt is $425,000, giving you up to $125,000 in borrowing capacity. Some lenders go to 90% combined LTV, but at higher interest rates. Your actual approval also depends on credit score, income, and debt-to-income ratio.

What is a HELOC and how is it different from a home equity loan?

A HELOC (Home Equity Line of Credit) is a revolving credit line secured by your home — similar to a credit card. You draw what you need, repay, and draw again during the draw period (typically 10 years), then repay the balance over a repayment period. A home equity loan is a lump-sum fixed-rate loan. HELOCs typically have variable rates and are better for ongoing costs (renovations, tuition). Home equity loans suit one-time large expenses where you want payment certainty.

How long does it take to build 20% equity?

It depends on your down payment, loan type, interest rate, and home appreciation. With a 5% down payment on a 30-year mortgage at 7%, it takes roughly 8–10 years to reach 20% equity through payments alone (without appreciation). With home price appreciation of 3% annually, you might reach 20% equity in 4–6 years. A 20% down payment means you start at 80% LTV immediately, avoiding PMI from day one.

Does refinancing reset my equity?

Refinancing itself does not reduce equity — your equity is unchanged by replacing one loan with another at the same balance. However, a cash-out refinance does reduce equity because you borrow additional funds against your home. Rate-and-term refinancing (same balance, new rate or term) leaves equity intact. After a refi, you restart the amortization schedule, which means your early payments are again weighted more toward interest, slowing future equity buildup slightly.

Can I use a HELOC to buy an investment property?

Yes, many investors use HELOC funds as a down payment on investment properties — this is sometimes called the BRRRR strategy (Buy, Rehab, Rent, Refinance, Repeat). However, using HELOC funds for an investment property makes the interest on that portion tax-deductible as investment interest rather than mortgage interest. Consult a tax advisor. Also be aware that using your primary home as collateral for an investment increases your financial risk if the investment performs poorly.

Home Equity Calculator

The Home Equity Calculator shows how much of your home you actually own by simulating your loan amortization to find the current remaining balance. Enter your home's current value, original loan details, and how long you have been paying — the calculator shows your equity, loan-to-value (LTV) ratio, and how much you may be able to borrow through a HELOC or cash-out refinance based on the standard 85% combined LTV limit used by most lenders.

Current Home Value

Current market value or appraisal

Original Loan Amount

Amount borrowed at origination

Loan Started

Annual Interest Rate

Loan Term

Available HELOC based on 85% combined LTV limit — actual approval depends on lender and credit profile.

Current Equity

$175,556.09

LTV Ratio

68.1%

Current Loan Balance

$374,443.91

Available HELOC Equity

$93,056.09

How to use this calculator

1
Enter current home value
Use a recent appraisal, Zillow/Redfin estimate, or a comparative market analysis from a local agent. Home equity depends on current market value, not what you paid.
2
Enter original loan amount
The original principal you borrowed when you took out the mortgage — not the purchase price. Find this on your original loan documents or closing disclosure.
3
Select how many years ago you started the loan
This determines how many months of amortization to simulate. The calculator computes your current balance by tracking principal paid each month.
4
Enter your interest rate and loan term
Your original annual interest rate and the loan term (usually 15 or 30 years). These are needed to calculate accurate amortization.
5
Review equity and HELOC availability
The calculator shows your equity in dollars and as LTV percentage. If LTV is below 85%, you may be able to access some equity via a HELOC — the available amount is shown based on an 85% combined LTV limit.

Formula

Monthly Rate = Annual Rate / 12 / 100
Monthly Payment = Loan × [r(1+r)^n] / [(1+r)^n - 1]
  where r = monthly rate, n = loan term in months

Current Balance = Loan × [(1+r)^n - (1+r)^m] / [(1+r)^n - 1]
  where m = months already paid

Current Equity = Current Home Value − Current Balance
LTV = (Current Balance / Current Home Value) × 100

Available HELOC = (Current Home Value × 0.85) − Current Balance

Amortization is computed using the standard mortgage formula. Each month, interest accrues on the outstanding balance, and the remainder of the fixed payment reduces principal. After m months of payments, the remaining balance can be calculated directly without simulating each month individually using the formula above. Most HELOC lenders cap the combined LTV (first mortgage + HELOC) at 85%, so available equity = 85% of home value minus the current first mortgage balance. Example: $500,000 home, $250,000 current balance → equity = $250,000 (50% LTV). Available HELOC = $500,000 × 0.85 − $250,000 = $175,000.

Worked Example

Current Home Value: $550,000 Original Loan Amount: $400,000 Loan Started: 5 years ago (60 months paid) Annual Rate: 6.5% Loan Term: 30 years Monthly Rate (r): 0.065 / 12 = 0.005417 Total Months (n): 360 Monthly Payment: $2,528 Current Balance after 60 months: ~$374,750 Current Equity: $550,000 - $374,750 = $175,250 LTV: $374,750 / $550,000 = 68.1% ✓ (below 80% — excellent) Available HELOC: $550,000 × 0.85 - $374,750 = $92,750

Frequently Asked Questions

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