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Buying Budget

Mortgage Deposit Calculator

Estimate only

Your deposit decides which mortgages you can apply for and, usually, what rate you are offered. Enter a property price and a target deposit percentage to see the amount needed, the gap from your current savings and how long that gap might take to close.

Common thresholds are 5%, 10%, 15%, 20% and 25%.

Deposit required

£25,000

£10,000 still to save.

Current deposit

£15,000

Current deposit percentage

6.0%

Remaining to save

£10,000

Mortgage needed today

£235,000

Loan-to-value today

94.0%

Estimated time to target

1 year 8 months

Estimate only

This is an illustration of saving arithmetic. It excludes interest earned on savings, Lifetime ISA bonuses, gifted deposits and changes in property prices.

How this calculation works

The deposit required is the property price multiplied by your target percentage. The shortfall is that figure less your current savings, and the time to target divides the shortfall by your monthly saving, rounded up to a whole month.

required deposit = price × target %
shortfall = required deposit − current savings
months to target = ceil(shortfall ÷ monthly saving)
LTV = (price − current savings) ÷ price

Assumptions

  • Savings grow only by the monthly amount you enter — no interest or investment growth.
  • The property price stays the same while you save.
  • The whole of your savings is available as a deposit.

Limitations

  • Does not include a Lifetime ISA government bonus, gifts or shared-ownership structures.
  • Lender minimum deposits vary by property type; new-build flats often require more.
  • Does not include buying costs — use the buying-costs calculator for those.

Last reviewed: 1 September 2026 · Calculation version 1.0.0

Next in your journey

Mortgage Repayment Calculator

Estimate monthly payments, total repaid and total interest, with a year-by-year amortisation schedule.

Open Monthly repayment calculator

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