Your First Home mortgage calculator: what you need to borrow

What this mortgage calculator shows

Enter a home price and the calculator shows the mortgage you would need under Your First Home, the monthly payment at the rate and term you choose, and the household income a lender would usually want to see. Add your income under “More options” and it turns the question round: the most you could borrow, the biggest home the scheme would then allow, and the deposit that goes with it.

The mortgage is 77.5% of the price because you provide 2.5% and the government lends 20% (GOV.UK). On a £230,000 home that is £178,250, or about £1,042 a month at 5% over 25 years.

Why the rate is lower than a 95% mortgage

Lenders price by risk, and risk tracks the loan-to-value (the mortgage as a share of the price). On 26 September 2026 the best fixed rates from lenders operating across England were about 5% at 75% to 80% loan-to-value and about 5.55% at 95%, according to the HomeOwners Alliance rate table. A 77.5% mortgage sits in the cheaper band, which is why the calculator’s default rate (5%) is lower than the rate it uses for the 95% comparison (5.55%). Set your own quotes to see your own numbers.

How the income figure is worked out

The calculator uses the common rule that lenders lend up to about 4.5 times household income. It is a rule of thumb, not a promise: lenders also look at your outgoings, debts, credit history, the mortgage term and, for a scheme purchase, the equity loan itself (MoneyHelper). Some lend more to strong applicants, some less.

The scheme’s own income cap and price caps, both due at the Budget on 28 October 2026, may cut these figures off before the lender does.

What will lenders check on a Your First Home mortgage?

Nothing has been published about lender requirements for the new scheme, so the best guide is how Help to Buy mortgages worked, and three points from that experience matter for this calculator. First, the mortgage had to be a repayment mortgage that you arranged yourself, and the scheme’s own rule was that it “should be less than 4.5 times your annual income (before tax)”, which is where this calculator’s multiple comes from (GOV.UK homebuyers’ guide). Second, the scheme required that “you must be able to afford the monthly fee and interest payments” on the equity loan once they started, so the loan counted as a future commitment even while it was interest-free, and a lender’s own affordability figure could come in below the simple multiple (GOV.UK homebuyers’ guide). Third, lenders ran their usual checks on top: outgoings, debts, credit history and the term, and only lenders that chose to take part offered scheme mortgages, which is likely again.

Behind all of this sits the Bank of England rule that keeps mortgages of 4.5 times income or more to 15% of new lending across the market; since July 2025 individual lenders may go above that share while the market as a whole stays within it (Bank of England). So the income figure here is a floor to aim above, not a target. If your household income is close to it, the income cap page explains the other limit that may apply, and a regulated mortgage adviser can tell you what real lenders will offer once the scheme opens.

Term, rate and what they do to the payment

A longer term lowers the monthly payment and raises the total interest. The £178,250 mortgage costs about £1,042 a month over 25 years, about £957 over 30 years and about £1,176 over 20 years at 5%. Each 0.5 percentage point on the rate moves the 25-year payment by roughly £52 a month. Test both in “More options”; the point of the exercise is to find a payment you could keep up if rates rose when your fixed deal ended.

What the calculator cannot know

Which lenders will take part, whether they will charge scheme-specific rates, how they will treat the equity loan interest from year six, and what the Budget will change. New-build mortgages also have their own quirks, including offer periods that can expire before a home is finished; the new-build mortgages guide covers them.