Deposit Savings Calculator

Enter your target property price, the deposit percentage you're aiming for, what you've saved so far, and how much you can put away each month. The calculator shows when you'll hit your target — and how a Lifetime ISA's 25% government bonus can shorten the timeline.

How the calculation works

Each month we add your contribution to your running balance and apply one twelfth of the annual interest rate. If you've ticked the Lifetime ISA box, contributions are capped at £4,000 per tax year and a 25% government bonus is added (£1,000 max per year). We assume contributions restart every April for the new tax year.

The "monthly savings contribution" you enter is the total going into the LISA only when the box is ticked. If you're saving more than £333 a month, you'll exceed the £4,000 LISA annual cap — the spillover should go into a normal ISA or savings account to keep earning interest. The calculator handles this automatically and shows the spillover in the breakdown.

What this calculator doesn't include

• House price growth. If property prices rise faster than your savings grow, your "5% of £350k" target moves with them. A useful rule of thumb: assume property grows 3–5% a year above today's price.
• Stamp duty and moving costs. Your deposit isn't your full upfront cost. Use the moving costs calculator to see SDLT, conveyancing, survey and removals on top.
• Tax on savings interest. Most basic-rate taxpayers have a £1,000 Personal Savings Allowance. Above that, interest is taxable. Cash ISAs sidestep this.

How to speed up the timeline

• Lifetime ISA: free 25% bonus if you're 18–39 and a first-time buyer. Up to £1,000/year of "free money".
• Match your partner's contributions: doubling monthly savings is the single biggest lever in this calculator.
• Take a 10% deposit instead of 15–20%: lender rates on 90% LTV are noticeably higher, but moving 12 months earlier may matter more than the interest difference. Run both scenarios.
• Workplace bonus / sharesave: lump sums from sharesave schemes or annual bonuses compress timelines significantly.
• Higher-interest savings: every percentage point of interest on £30k+ adds up. The current 4–5% range is historically high.

Once you have your deposit

The next questions are usually how much you can borrow, and what the full purchase will cost:

• Affordability calculator — how much you can actually borrow
• Mortgage repayment calculator — what the monthly payment will look like
• Moving costs calculator — SDLT plus solicitor, survey, removals
• FTB stamp duty calculator — relief at £300k / £500k thresholds

Calculation rules last reviewed: 18 May 2026.