Home Equity Loan Calculator

What this calculator is, and when to reach for it

A home equity loan is the plainest way to borrow against a property you already own: a single lump sum, a fixed rate, equal monthly payments, and a definite end date. It sits behind your existing mortgage as a second charge, which is why it is sometimes called a second mortgage.

Its virtue is predictability. Unlike a credit line there is no draw period, no variable rate, and no payment that transforms after ten years. You know on day one what every payment will be and when the last one falls. For a known, one-off cost, that certainty is worth a good deal.

Its defining advantage over unsecured borrowing is the rate, and its defining risk is the reason for that rate: the loan is secured on your home. A personal loan that goes wrong damages your credit. A home equity loan that goes wrong puts the property at risk, and no rate saving changes that arithmetic.

Reach for this page when you have a fixed sum to fund — a renovation with a firm quote, a large one-off expense — and want to know the payment and total cost, or when you are weighing it against a credit line or a cash-out refinance.

The three ways to borrow against a home

A home equity loan gives you a fixed sum at a fixed rate as a second charge, leaving your first mortgage untouched. A credit line gives you a revolving limit at a variable rate, useful when the amount or timing is uncertain. A cash-out refinance replaces the first mortgage entirely with a larger one.

The choice usually turns on two questions. Do you know exactly how much you need, and is your existing mortgage rate better than what is available today? A known sum plus a good existing rate points firmly at a home equity loan, because it prices only the new borrowing.

Where the existing rate is worse than current market rates, a cash-out refinance can genuinely make sense, since repricing the whole balance downward is a benefit rather than a cost. That situation is the exception rather than the rule.

Where to go next

To see how much you could borrow, the home equity calculator shows what a lender cap leaves available, and the combined loan to value calculator gives the ratio a second-charge lender actually assesses.

For the two alternatives, the HELOC calculator models a revolving line with its two-phase structure, and the cash-out refinance calculator models replacing the first mortgage.

Because this is ordinary fixed-rate borrowing, the loan repayment calculator shows what overpaying would achieve, and the loan comparison calculator weighs it against an unsecured personal loan — worth doing, since paying more for borrowing that cannot cost you your home is sometimes the better trade.

How the loan and the borrowing limit are worked out

Two calculations: how much a lender would advance, and what the resulting loan costs.

available = (value × cap) − first mortgage   |   M = P × [ r(1 + r)ⁿ ] ÷ [ (1 + r)ⁿ − 1 ]

cap

the lender’s maximum share of value across all secured borrowing

P

the lump sum borrowed under the second charge

r

the monthly rate, fixed for the life of this loan

n

the number of monthly payments in the term

Why a second charge costs more than a first

If a property is sold or repossessed, the first-charge lender is repaid before the second sees anything. The second-charge lender is therefore exposed to the last slice of the property’s value, which is the part most likely to evaporate if prices fall.

That ranking, not your creditworthiness, is the main reason the rate is higher. A borrower with an impeccable record still pays a premium on a second charge, because the risk being priced belongs to the position of the loan rather than the person holding it.

The cap counts everything, not just this loan

Lenders limit total secured borrowing to a share of value, so the amount available is the cap applied to the property less what the first mortgage already claims. This is why a household with substantial equity can still be offered comparatively little.

It also means a fall in property value reduces borrowing capacity far faster than it reduces equity, since capacity is the difference between two large numbers. A modest valuation shortfall can remove a disproportionate share of what you expected to borrow.

Fixed rate, fixed payment, and why that matters here

Because both the rate and the term are fixed, the total cost of the loan is knowable on the day you sign, and it does not change. There is no draw period ending, no rate reset, and no payment that transforms partway through.

For a secured debt, that predictability is worth more than it would be on an unsecured loan. The consequence of falling behind is severe enough that certainty about what you owe each month is a genuine feature rather than a convenience.

What the term does to the total

A longer term lowers the payment and raises total interest, as with any amortizing loan. On secured borrowing the temptation to stretch is stronger, because the rate is low and the monthly difference looks manageable.

The discipline worth applying is to match the term to the life of what you are funding. A fifteen-year loan for a kitchen that will need replacing in twelve is a debt outliving its purpose, and secured borrowing makes that mismatch more consequential than it would otherwise be.

What this page assumes

The calculator works out a level monthly payment on the lump sum you entered, then adds that loan to your existing mortgage to show the combined share of property value.

Lender caps on the combined share of property value differ by lender. The cap you enter is a reference figure, not a limit this page sets.

Worked examples, step by step

Take a 50,000 home equity loan at 8.0% over fifteen years, secured behind an existing mortgage.

What the loan costs

The payment is 477.83, unchanging for fifteen years, and the total interest is 36,008.69 — roughly 72% of the sum borrowed. That is the honest cost of spreading a secured debt across fifteen years even at a comparatively modest rate.

The predictability is real: 180 identical payments, a known end date, and no possibility of the rate moving. But the total is worth sitting with, because the low monthly figure is a consequence of the long term rather than of cheap borrowing.

The same loan over ten years

Shortening to ten years raises the payment to roughly 607 and cuts total interest to about 22,800 — a saving of some 13,200 for an extra 129 a month.

That is a strong return on a modest increase, and it is the calculation most borrowers do not run because the fifteen-year payment was the one presented. Decide the shortest term you can comfortably service, then check the payment, rather than the other way round.

Against the unsecured alternative

A personal loan for the same 50,000 would carry a materially higher rate and a shorter term, producing a larger payment and, quite possibly, less total interest because of the compressed schedule.

It would also carry no claim on the property. Whether the rate saving on a secured loan justifies that difference is a judgement rather than a calculation, and it deserves to be made deliberately rather than defaulted into because the secured rate looked better.

The vocabulary, on and around this page

Home equity loan

A fixed-rate lump sum secured against a property you already own, repaid in equal instalments over a set term.

Second mortgage

Another name for a home equity loan, reflecting that it ranks behind the existing first mortgage.

Second charge

The legal position of the loan against the property. Being repaid after the first charge is why the rate is higher.

First charge

The primary mortgage, repaid first from any sale. Its priority is why it carries the keenest pricing.

Lender cap

The maximum share of property value permitted across all secured borrowing, which determines how much is available.

Available borrowing

The cap applied to the value, less the first mortgage. Always well below the equity held.

Combined loan to value

All secured debt as a share of value. This is the figure a second-charge lender assesses.

Fixed rate

A rate that cannot change for the life of the loan, making the total cost knowable from the first payment.

Lump sum

The full amount advanced at completion. Unlike a credit line, it cannot be drawn in stages or redrawn once repaid.

Amortization

The schedule by which each payment covers interest first and reduces the balance with the remainder.

Total interest

All interest across the life of the loan. On long terms it can approach or exceed the sum borrowed.

Term matching

Choosing a term no longer than the useful life of what the borrowing funds, so the debt does not outlive its purpose.

Home equity line of credit

The revolving, variable-rate alternative. Better where the amount or timing of the need is uncertain.

Cash-out refinance

Replacing the first mortgage with a larger one. It reprices the entire balance rather than only the new borrowing.

Unsecured borrowing

Lending with no claim on your property. More expensive, and it cannot cost you the home if things go wrong.

Subordination

An agreement by this lender to remain behind a new first mortgage. Usually required if you later refinance the main loan.

Closing costs

Fees to arrange the loan, such as valuation and legal work. Lower than a full refinance but not always negligible.

Prepayment penalty

A charge for repaying early. Worth checking, since it affects whether overpaying is worthwhile.

Equity

Property value less all secured debt. This loan converts part of it into cash and a corresponding increase in what you owe.

Repossession risk

The consequence of securing debt against a home. It is the reason a lower rate is compensation rather than a free gain.

Common mistakes, and what this page will not do

• Treating the lower rate as a free improvement. The rate is lower because your home secures the debt. That is compensation for accepting a much more serious consequence of default.
• Choosing the term by the payment. Ten years instead of fifteen costs 129 more a month and saves about 13,200 in interest on the worked example.
• Assuming your equity is what you can borrow. The cap covers all secured borrowing, so available funds are the cap applied to value less the first mortgage — usually far less than equity.
• Borrowing over a term longer than the purpose lasts. A fifteen-year loan for something that lasts twelve leaves a secured debt outliving what it paid for.
• Expecting first-mortgage pricing. A second charge is repaid after the first from any sale, so the premium reflects the loan’s position rather than your record.
• Using a lump-sum loan for staged spending. Interest runs on the whole sum from day one. For a renovation paid in stages, a credit line matches the need better.
• Overlooking subordination if you may refinance. Refinancing the first mortgage later normally needs this lender’s agreement to stay behind, and it is not automatic.
• Not pricing the unsecured alternative. A personal loan costs more in rate and cannot touch the property. Sometimes that is the better trade.
• Ignoring how a valuation shortfall bites. Capacity is the gap between a capped share of value and a fixed balance, so it falls much faster than the valuation does.

What this calculator leaves out: This calculator does not verify or produce a valuation, apply any specific lender’s cap or pricing, include closing costs or fees, model prepayment penalties, assess whether you would be approved, or account for tax treatment of interest. It applies fixed-rate amortization to the amount, rate, and term you enter.

Frequently asked questions