Guarantor Mortgage Calculator
Work out your loan-to-value, monthly repayments, and combined borrowing power on a UK guarantor mortgage backed by savings, property, or a guarantor’s income.
Guarantor Mortgage Details
Enter the property, loan and guarantor details to estimate your mortgage
The agreed purchase price of the property.
Cash deposit you’re putting towards the purchase yourself.
Estimated mortgage interest rate, as an annual percentage.
How your guarantor is supporting the mortgage application.
Savings or usable property equity your guarantor is putting up as extra security. Leave as 0 for income-backed only.
Only used for affordability if you select “Income-backed” above, or to show combined affordability generally.
How many times annual income the lender will typically lend.
Your Guarantor Mortgage Estimate
Loan-to-value, monthly repayments, and combined affordability
Enter your details above and click Calculate Mortgage to reveal your guarantor mortgage estimate.
Guarantor Mortgage LTV Bands
A quick reference for how loan-to-value bands typically relate to guarantor support and lender risk appetite in the UK.
| Loan-to-Value (LTV) | Risk Level | Guarantor Typically Needed? | Notes |
|---|---|---|---|
| Up to 75% | Low | Rarely | Standard mortgage rates usually apply |
| 75% – 90% | Moderate | Sometimes | Guarantor can improve rate or approval odds |
| 90% – 95% | High | Often | Guarantor support common at this band |
| 95% – 100% | Very High | Usually | Typical territory for guarantor mortgages |
| 100%+ (100% mortgage) | Maximum | Almost always | Guarantor security often covers full loan |
Guarantor Mortgage Calculator FAQ
Everything you need to know about guarantor mortgages, guarantor risk, and combined affordability in the UK.
A guarantor mortgage is a home loan where a family member or close relative agrees to support your application, usually by pledging savings, offering their property as security, or adding their income to the affordability assessment. This reduces the lender’s risk and can help buyers with a small deposit or lower income borrow enough to buy a home.
Borrowing limits depend on the lender, but many will use a combined income assessment, applying an income multiple (commonly 4 to 5.5 times income) to your income plus your guarantor’s income. Savings-backed or property-backed guarantor mortgages may instead allow a higher loan-to-value against the property itself, since the guarantor’s security reduces the lender’s exposure.
A guarantor is legally responsible for covering mortgage payments if the main borrower cannot pay. If savings are pledged as security, they can be at risk and may be tied up for several years. If a property is used as security, the guarantor’s home could potentially be repossessed in the event of serious repayment failure, so guarantors should always take independent legal advice before agreeing.
Most guarantor mortgage arrangements are reviewed after a set period, commonly three to five years, once the borrower has built up enough equity or a strong repayment history. At that point, the lender may release the guarantor’s savings or remove the charge over their property, provided the loan-to-value and affordability criteria are then met without the guarantor’s support.
It depends on the product. Some guarantor mortgages still require a small personal deposit alongside the guarantor’s savings or property security, while other 100% guarantor mortgages allow you to borrow the full purchase price if the guarantor’s security fully covers the lender’s risk. Requirements vary significantly between lenders.
An income-backed guarantor mortgage adds the guarantor’s income to the affordability assessment, increasing how much you can borrow based on combined income multiples. A savings-backed or property-backed guarantor mortgage instead uses the guarantor’s savings or home equity as additional security, which can allow a higher loan-to-value on the property being purchased rather than increasing the income multiple used.