House deposit calculator
Work out how long it will take to save your deposit at your current savings rate. See which mortgage rate tiers you could unlock and what other costs to budget for alongside your deposit.
One thing most first-time buyers underestimate is the costs on top of the deposit. Stamp duty, solicitor fees, a survey, mortgage arrangement fees and moving costs can easily add another 3-5% to your total upfront spend. Save for these separately from your deposit so you are not caught short on completion day.
How much deposit do I need?
The minimum deposit for most lenders is 5% of the property price. A 10% deposit opens up significantly better rates. 20% or more unlocks the most competitive deals.
Lifetime ISA
If you are under 40, a Lifetime ISA lets you save up to £4,000 per year toward a first home. The government adds a 25% bonus on top - that is up to £1,000 free per year.
Interest on your savings
Keeping your deposit savings in a high-interest account or cash ISA means your money works while you save. Even a few percent interest makes a meaningful difference over two to three years.
Property price changes
If property prices rise while you are saving, your target deposit grows too. This is why saving as much as possible as quickly as possible gives you more certainty about your purchase window.
Please note: This calculator provides estimates based on constant savings rates and monthly contributions. Actual timescales will vary. Stamp duty figures are estimates for England and Northern Ireland using 2025 rates for first-time buyers and assume the property is the only residential purchase. Always verify all costs with your solicitor before exchanging contracts. This is not financial advice.
Calculator results are estimates based on the information you enter and the assumptions built into the tool. They are illustrative only and should not be relied upon as accurate projections. Rates, thresholds and rules change regularly; always verify figures with an appropriate professional or official source before acting on them.
What is a house deposit calculator?
A house deposit calculator works out how long it will take to save a target deposit amount, based on your current savings balance, your monthly saving rate, and the interest rate your savings are earning. It accounts for the compounding effect of interest on your growing balance, so the timeline is slightly shorter than a simple division of the target by the monthly savings.
The calculator also shows how different saving rates or starting balances affect the timeline – useful for understanding which lever has the most impact on your deposit goal.
How to use this calculator
Deposit target: The total amount you want to save. For a £250,000 property with a 10% deposit, this is £25,000. Remember to also budget for buying costs on top of the deposit – stamp duty, conveyancing fees, and survey, which typically add £3,000 to £10,000 depending on the purchase price.
Current savings: How much you have already saved toward the deposit. If you have savings elsewhere that are not earmarked for the deposit, do not include them here.
Monthly savings: How much you plan to save each month specifically toward the deposit. Be realistic – the figure you will actually maintain, not the aspirational maximum.
Savings interest rate: The annual interest rate your deposit savings are earning. If they are in a cash ISA or easy-access account, enter the current rate. If you are unsure, 4% to 5% is typical for current competitive easy-access rates (check current rates — these change frequently).
Reading the result: The calculator shows your estimated timeline in months and years. It also shows the total interest earned over the savings period, which demonstrates the value of starting early and choosing a competitive savings rate.
How to save your deposit faster
Increase the monthly savings amount. Even modest increases have a significant effect over a multi-year saving period. The calculator shows the timeline change for different saving amounts.
Start with a larger initial deposit. If you already have savings (but perhaps in the wrong account), consolidating them into a dedicated deposit savings account — ideally a Lifetime ISA for first-time buyers or a high-rate cash ISA – immediately shortens the timeline.
Use a Lifetime ISA. The government adds a 25% bonus on LISA contributions up to £4,000 per year – effectively a guaranteed 25% return on that portion of savings. This is the highest available return on deposit savings for eligible first-time buyers. For more details, see the Lifetime ISA explainer.
Choose a competitive savings rate. The difference between 3% and 5% on £20,000 of savings is £400 per year. Over three years, that is £1,200 – approximately equivalent to four months of saving at £300 per month.
Frequently asked questions
How much deposit do I actually need? The minimum deposit for most residential mortgages is 5% of the purchase price, giving an LTV of 95%. However, a 10% deposit (90% LTV) gives access to more lenders and lower rates; a 15% deposit (85% LTV) is even better; and a 25% deposit (75% LTV) provides access to most lenders’ best rates. The right deposit target depends on your local property market and how quickly you want to buy.
Does the deposit have to come from my own savings? No – lenders accept gifted deposits from immediate family members, subject to a gifted deposit letter confirming the money is a gift and not a loan. Some lenders also consider Help to Buy equity loan funds and Lifetime ISA funds as part of the deposit.
Can I use a stocks and shares ISA for my deposit? Yes – but investment values fluctuate. If you plan to buy within three to five years, keeping the deposit in cash or a cash ISA is typically recommended to avoid the risk of a market fall reducing your available deposit close to your purchase date. For timelines of five years or more, some degree of investment can be considered.
What is the best account for saving a house deposit? A Lifetime ISA (for eligible first-time buyers under 40) offers the 25% government bonus on top of the savings interest. Beyond the LISA limit of £4,000 per year, a high-rate cash ISA or easy-access savings account is appropriate. Avoid keeping large sums in a current account where the interest rate is typically zero or negligible.
The information on this site is for educational and informational purposes only. Nothing on Be More Peter constitutes financial advice, and nothing should be treated as such. The calculators, articles and tools on this site are designed to help you understand financial concepts and run indicative numbers - they are not a substitute for professional advice tailored to your specific circumstances. Before making any financial decision - including decisions about mortgages, pensions, investments, savings or insurance — you should seek independent financial advice from a qualified adviser who is authorised and regulated by the Financial Conduct Authority (FCA). Calculator results are estimates based on the information you enter and the assumptions built into the tool. They are illustrative only and should not be relied upon as accurate projections. Rates, thresholds and rules change regularly - always verify figures with an appropriate professional or official source before acting on them. Be More Peter is not authorised or regulated by the FCA. The content on this site does not constitute a financial promotion.
Related tools and posts
- Mortgage affordability calculator — how much you can borrow with your deposit
- LTV calculator — which rate tier your deposit achieves
- Stamp duty calculator — the tax on top of your deposit
- ISA calculator — model your savings in a tax-free wrapper
- How to save for a house deposit — the realistic version
- What is a LISA and who should open one?