Home Equity Line of Credit Calculator
Find how large a home equity line you may qualify for, based on your home’s value, your mortgage balance and your lender’s maximum combined loan-to-value.
A worked example
Running this tool on current national benchmarks (Federal Reserve / Freddie Mac via FRED (St. Louis Fed)) — swap in your own numbers to see how the result moves.
- Home value
- $450,000
- Mortgage balance
- $250,000
- Max combined loan-to-value
- 85%
- HELOC interest rate
- 8.50%
- Repayment term (years)
- 15
up to 85% combined loan-to-value
- Home equity$200,000
- Current loan-to-value55.6%
- Max you can borrow$382,500
How the available credit line changes with home value
Holding the other inputs at the example above, here is how the result moves as home value changes.
| Home value | Available credit line | Home equity |
|---|---|---|
| $350,000 | $47,500 | $100,000 |
| $450,000 | $132,500 | $200,000 |
| $600,000 | $260,000 | $350,000 |
| $800,000 | $430,000 | $550,000 |
The math behind it
This estimates how large a HELOC you might qualify for. It multiplies your home's value by the lender's maximum combined loan-to-value ratio to get the total secured debt allowed, then subtracts your existing mortgage balance. What remains is your available credit line. It also shows your current loan-to-value, your equity, and — if you drew the full line — an illustrative amortized repayment schedule at the rate and term you enter.
Assumptions & limits
- Available credit equals home value times the max combined loan-to-value, minus your current mortgage balance.
- The combined loan-to-value cap covers your mortgage plus the new line together, not the line alone.
- The repayment schedule assumes you draw the entire available line and repay it as a fixed amortizing loan — real HELOCs are usually variable-rate with an interest-only draw period first.
- It does not model your income, credit score or debt-to-income, which lenders also use to set the actual limit.
How HELOC size is bounded
Conceptual limits; each lender sets its own maximum combined loan-to-value and underwriting rules.
| Factor | Effect on your line |
|---|---|
| Max combined loan-to-value | Caps mortgage + HELOC as a share of home value |
| Existing mortgage balance | Subtracted from the cap to find room left |
| Home value | Sets the total dollar amount the cap allows |
Common questions
What is combined loan-to-value and why does it cap my line?
Combined loan-to-value (CLTV) is your total home-secured debt — mortgage plus HELOC — divided by the home's value. Lenders cap it, often around 80 to 90 percent, to keep an equity cushion. Your available line is whatever room is left under that cap after your existing mortgage, which is exactly what this calculator computes.
Is the amount shown guaranteed?
No. This is the ceiling that your equity and the CLTV cap allow. Lenders also underwrite your income, credit score and debt-to-income ratio, any of which can lower the offer. Treat the figure as the maximum your home could support, not a pre-approval.
How does a HELOC's interest rate usually work?
Most HELOCs carry a variable rate priced as an index (commonly the prime rate) plus a margin set by the lender, so your rate moves when the index moves. The single rate you enter here is for illustration — build in room for rate increases when you plan the payment on a variable line.