Enter the price of the home and your deposit, as a percentage of the price or as an amount. You get the mortgage you need, your loan to value (LTV) and the cash you need once Stamp Duty and fees are added. Add your savings and what you put aside each month to see how long the rest will take, with the Lifetime ISA bonus if you save in one. It works the same way in England, Scotland, Wales and Northern Ireland.
Deposit and loan to value
Your deposit is the part of the price you pay yourself, and the mortgage covers the rest. Loan to value is the mortgage as a share of the price: a 10% deposit means a 90% LTV. Stamp Duty and fees are not part of the deposit. They are paid on top, so enter them as upfront costs to see the total cash you need.
LTV bands
Mortgage rates are quoted by LTV band. Every month the Bank of England publishes the average quoted 2-year fixed rate at 60%, 75%, 85%, 90% and 95% LTV, leaving out deals only for first-time buyers. The calculator shows the band your loan falls in, that band’s latest average rate, and how much more deposit would take you down to the next band. Your own rate depends on the lender and on you.
Small deposits and the guarantee scheme
There is no legal minimum deposit. Since July 2025 the government’s permanent Mortgage Guarantee Scheme has covered loans above 90% and up to 95% of the price across the UK, so lenders taking part can offer mortgages with a 5% deposit. Above 95% LTV you are beyond the Bank of England’s highest band and beyond the scheme.
Saving with a Lifetime ISA
You can open a Lifetime ISA from 18 and before 40 and pay in up to £4,000 a year; the government adds a 25% bonus, up to £1,000 a year. The money can go towards a first home costing £450,000 or less, bought with a mortgage at least 12 months after your first payment in. If you buy with someone who has their own Lifetime ISA, choose two. The calculator counts the bonus in the month you pay in, on up to £4,000 in each 12 months, and leaves out interest.
Rounding
Amounts are rounded to the nearest penny and percentages to two decimal places, with halves rounded up. The months to save are rounded up to a whole month, because a month started has to be saved in full.
Deposit = percentage × price.
Mortgage = price − deposit.
Loan to value = mortgage ÷ price.
Cash needed = deposit + Stamp Duty and other upfront costs.
Months to save = (cash needed − savings) ÷ monthly saving, rounded up. With a Lifetime ISA, each month also adds 25% of what you pay in, on up to £4,000 a year per account.
Example: a £300,000 home with a 7.5% deposit
A 7.5% deposit is £22,500.00, which leaves a £277,500.00 mortgage: a 92.5% LTV, in the 95% band and in the range covered by the Mortgage Guarantee Scheme. Another £7,500.00 would take you down to the 90% band. With £5,000 of Stamp Duty and fees, you need £27,500.00 in all. With £5,000 already saved and £500 a month put aside, £4,000 a year of it in a Lifetime ISA, the remaining £22,500.00 takes 39 months, £3,375.00 of it from the bonus.
