Skip to content
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.
Explore budget trade-offs with AI

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

Planning the deposit without emptying your savings

A worked deposit comparison

On a £240,000 property, 5% is £12,000, 10% is £24,000 and 15% is £36,000. If you have £18,000 saved, reaching 10% requires another £6,000. At £500 a month that is 12 months before interest or changes in the property price. The saving-time figure assumes steady contributions and a fixed target; it is not a forecast of when a home will be affordable.

Choose the right cash figure

Separate the deposit from your emergency reserve and one-off buying costs. A £24,000 balance does not fund a £24,000 deposit if you also need cash for a solicitor and a survey. A gifted deposit may need a declaration and evidence of where the money came from. Lenders and conveyancers will check the source of funds, so keep a clear trail rather than moving money between accounts without records.

A bigger deposit is only one part of the decision

Moving into a lower LTV band can change the products available, but it does not guarantee a particular rate or approval. Compare the repayment impact with the time and rent cost of saving longer. If the property price rises, the cash target rises too. Try a higher price and a lower monthly contribution to see how resilient the saving plan is.

Further reading: MoneyHelper — how much deposit do I need for a mortgage?. Examples are illustrations using stated inputs, not quotes or personal recommendations.

See our method and limitations or report a correction.

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

All calculators