How much equity you can borrow through a HELOC depends on two numbers: the current value of the property and the outstanding mortgage balance. The maximum HELOC facility is calculated by applying the combined LTV cap (typically 85% in the UK) to the property value and subtracting the existing mortgage. This calculator shows the available borrowing at four LTV tiers so the borrower can see how much is accessible at each level and understand how the LTV position affects the rate tier. All figures are illustrative only.
At a Glance
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Enter the property value and the outstanding mortgage balance. The calculator shows the available HELOC facility at 65%, 70%, 75%, 80%, and 85% combined LTV.
Lower combined LTV typically qualifies for a more competitive rate. The tool shows the available amount at each tier so the borrower can see the trade-off: a smaller facility at a lower LTV may qualify for a better rate than the maximum available at 85%.
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The maximum combined LTV for UK HELOC products is typically 85%. No UK HELOC product currently offers 90% or 100% combined LTV.
The calculation uses the full HELOC facility limit, not the amount the borrower plans to draw. This is because the lender’s risk exposure is based on the maximum the borrower could draw at any point during the draw period. Requesting a facility larger than needed pushes the combined LTV higher and may move the borrower into a less competitive rate tier.
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The LTV-based figure is a theoretical maximum. Affordability sets the practical maximum. Both must be satisfied for the application to proceed.
Even where the equity position supports a large facility, the lender will limit the amount to what the borrower can afford to repay based on income and existing commitments. For many borrowers, affordability rather than LTV is the binding constraint. The guide to HELOC eligibility covers the full assessment.
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HELOC facility limits typically range from £5,000 to £500,000. Even where the LTV supports a larger figure, the provider’s maximum facility cap applies.
The minimum facility is typically £5,000. The maximum is typically £500,000 at the time of writing. Amounts below the minimum or above the maximum are shown as outside the current product range, regardless of the LTV position.
How much equity can you borrow?
Illustrative figures only. Subject to affordability and provider limits (£5,000 to £500,000).
Current equity
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Current LTV (mortgage only)
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Formula: (property value x LTV%) minus outstanding mortgage = available HELOC facility. The calculation uses the full facility limit, not the planned draw amount. Amounts shown are subject to affordability assessment and provider lending limits (typically £5,000 to £500,000 at the time of writing). Minimum property value for a UK HELOC is typically £100,000. This calculator does not constitute a quote, offer, or financial advice.
About this tool
What it calculates
Available borrowing at five LTV tiers from your equity position
The calculator applies the standard LTV formula at 65%, 70%, 75%, 80%, and 85% combined LTV, showing how much HELOC facility the equity position supports at each level. It also shows the current equity and the current mortgage-only LTV as reference points. Amounts below £5,000 or above £500,000 are flagged as outside the current product range.
Why the tiers matter
Lower combined LTV typically means a lower rate
The rate offered on a HELOC is influenced by the combined LTV. Borrowers at below 65% combined LTV are typically offered the most competitive rates. Rates increase at higher LTV tiers, with the widest margins at 80% to 85%. The guide to HELOC rates in the UK includes illustrative rate bands by LTV tier.
How to use this calculator
Enter your property value
Use the most recent valuation or a realistic estimate based on comparable sales in your area. If you are unsure, online tools from Zoopla or Rightmove can provide an indicative figure, though the lender will carry out their own valuation (typically via an automated valuation model). The minimum property value for a UK HELOC is typically £100,000 at the time of writing.
Enter your outstanding mortgage balance
This is the amount currently owed on the existing mortgage, not the original loan amount. The most recent mortgage statement or an online balance check with the lender will have the current figure. If there is no mortgage on the property, set this to zero.
Read the tier breakdown
The output shows the available facility at each LTV tier. The most competitive rates are typically at 65% and below. The maximum available is at 85%, which is the cap for UK HELOC products. The difference between the tiers shows how much more could be borrowed by accepting a higher LTV (and potentially a higher rate). The guide to understanding LTV for HELOCs explains the rate impact in detail.
Understanding the results
The equity summary at the top shows two figures: the current equity (property value minus outstanding mortgage) and the current mortgage-only LTV. These are the starting position before a HELOC is added. The current LTV indicates how much headroom exists between the existing mortgage and the 85% cap.
The tier breakdown shows the available HELOC facility at each combined LTV level. “Combined LTV” means the existing mortgage plus the full HELOC facility, expressed as a percentage of the property value. A combined LTV of 70% means the mortgage and the HELOC together account for 70% of the property value, leaving 30% equity as a cushion. The wider the equity cushion, the lower the risk from the lender’s perspective, and the more competitive the rate offered.
If the existing mortgage already exceeds a particular LTV threshold, the available amount at that tier is zero. For example, a property valued at £250,000 with a £200,000 mortgage (80% LTV) has no room for a HELOC at 65%, 70%, 75%, or 80% combined LTV. The only tier with available capacity is 85%, which supports a maximum facility of £12,500. The guide to understanding LTV for HELOCs covers how to improve the LTV position through mortgage overpayments, property value growth, or requesting a smaller facility.
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Checking won’t harm your credit scoreFrequently asked questions
Why does the calculator show different amounts at each LTV tier?
Each tier represents a different maximum combined LTV. At 65%, the mortgage plus HELOC facility cannot exceed 65% of the property value. At 85%, they cannot exceed 85%. The higher the tier, the more of the property value is committed to secured borrowing, which means less equity cushion. The available amount at each tier is simply the difference between the tier threshold and the existing mortgage balance.
The rate offered by the lender is influenced by which tier the combined LTV falls into. Borrowers at lower tiers (below 65%) typically access the most competitive rates because the lender’s risk exposure is smallest. Borrowers at higher tiers (80% to 85%) typically pay more because the equity cushion is thinner. This means requesting a facility at a lower LTV tier may save more in rate over the term than the additional borrowing capacity at the higher tier would provide.
The guide to HELOC rates in the UK includes illustrative rate bands showing the typical rate difference between tiers. The guide to understanding LTV for HELOCs covers the full mechanics of how LTV affects the rate and facility amount.
What if my mortgage already puts me above 85% LTV?
If the outstanding mortgage already exceeds 85% of the property value, there is no room for a HELOC at the current position. This can happen when the property was purchased with a high LTV mortgage and has not yet been paid down significantly, or when property values have fallen since purchase. The calculator will show zero available at all tiers in this situation.
Three routes can improve the position over time. Reducing the mortgage balance through regular payments or overpayments directly lowers the LTV. Property value appreciation improves the ratio without the borrower doing anything, though it is not controllable or predictable. For borrowers close to the threshold, a combination of modest overpayments and natural property price growth may bring the LTV within range over twelve to twenty-four months.
For borrowers who need to borrow now and whose LTV exceeds 85%, standard secured loans from specialist providers may offer higher combined LTV (up to 90% or occasionally above), though these are lump-sum products without the revolving drawdown feature of a HELOC. The guide to alternatives to a HELOC covers the full range of options.
Does this calculator account for affordability?
No. The figures shown are based on the equity position only. The lender will also assess affordability based on the borrower’s income and existing commitments, tested at a stressed interest rate to allow for potential rate increases. For many borrowers, particularly those with modest incomes or significant existing commitments, affordability rather than LTV is the factor that limits the maximum facility.
As a rough guide, the lender calculates the monthly repayment at the stressed rate and checks that this is affordable alongside the existing mortgage payment and all other regular commitments. The monthly affordability checker provides an indicative estimate. The guide to HELOC eligibility covers the affordability assessment in detail, including how self-employed income is treated.
In practice, borrowers should treat the LTV-based figure as the upper ceiling and the affordability-based figure as the practical limit. The lower of the two determines the maximum facility the lender will offer.
Can I use this for a property with no mortgage?
Yes. Set the mortgage balance to zero. The available borrowing at each tier is simply the property value multiplied by the LTV percentage. A property worth £400,000 with no mortgage has £260,000 available at 65% combined LTV, £320,000 at 80%, and £340,000 at 85%. All amounts remain subject to the provider’s maximum facility limit (typically £500,000) and the affordability assessment.
Properties owned outright produce the lowest combined LTV for any given facility size, which typically qualifies for the most competitive rates. A £50,000 HELOC on a £400,000 unmortgaged property produces a combined LTV of just 12.5%, which is well within the most competitive tier. The guide to HELOC rates in the UK covers how the LTV position affects the rate offered.
One consideration for unmortgaged properties: the HELOC registers a second charge on the property. For homeowners who have worked to pay off their mortgage and own the property free of any charge, adding a new charge is a significant decision even at a low LTV. The property is at risk if repayments are not maintained, regardless of the LTV position. The guide to HELOC risks explained covers the risk profile in detail.
How accurate is the property value I should use?
Use the most realistic estimate available. The lender will carry out their own valuation, typically using an automated valuation model (AVM) that estimates value based on comparable sales data and property records. If the AVM figure differs from the borrower’s estimate, the lender’s figure determines the LTV and therefore the facility amount. An optimistic property value entered into this calculator will overstate the available borrowing.
Online valuation tools from Zoopla, Rightmove, and similar platforms can provide a useful starting point, though they should be treated as indicative rather than definitive. Recent comparable sales of similar properties in the immediate area are the most reliable reference point. If the property has undergone significant improvements since the last comparable data, the AVM may not capture the full value, and a physical RICS valuation may be needed (at the borrower’s expense) to reflect the current condition.
For planning purposes, using a conservative property value in this calculator provides a more realistic picture of the available borrowing than an optimistic one. If the AVM comes in higher than expected, the available facility may be larger than shown. If it comes in lower, planning around the conservative figure avoids disappointment. The guide to HELOC eligibility covers the valuation process.
Squaring Up
The equity available for a HELOC is determined by the property value, the outstanding mortgage balance, and the combined LTV cap (typically 85% in the UK). Lower combined LTV tiers typically qualify for more competitive rates, which means the cheapest borrowing is not always the maximum available. The calculator shows the available amount at five tiers so the borrower can see the trade-off between borrowing more and borrowing at a better rate.
The LTV figure is a ceiling, not a guarantee. Affordability, credit profile, and provider lending limits all apply on top of the equity position. For a complete picture of eligibility, the LTV calculation from this tool should be considered alongside the affordability assessment covered in the HELOC eligibility guide.
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Checking won’t harm your credit score Check eligibilityThis calculator is for illustrative purposes only and does not constitute financial advice, a quote, or an offer. Your home may be at risk if you do not keep up repayments on a mortgage or other debt secured against it. The figures shown are based on the equity position only and do not account for affordability, credit profile, or provider-specific lending criteria. The maximum combined LTV, minimum facility, and maximum facility limits reflect typical conditions at the time of writing and may vary between providers. Actual amounts depend on individual circumstances.
