House Deposit Calculator: How Much Do You Need to Save?

Use the house deposit calculator

Enter the price of the property you have your eye on, the deposit percentage you want to put down, and the amount you can save each month. The calculator above returns the deposit in pounds, the loan you would need, and an estimated number of months to reach the target. Adjust the percentage to see how a bigger deposit changes the size of the mortgage.

Why your deposit size matters more than people think

The deposit is the slice of the purchase price you pay yourself. The rest comes from the mortgage. Buyers often fixate on the headline number, but the percentage is what lenders care about, because it sets your loan-to-value (LTV) ratio: the proportion of the price you are borrowing.

A larger deposit means a lower LTV, and lenders price mortgages in LTV bands. Cross from a 90% loan to an 85% or 75% loan and you typically unlock a cheaper interest rate, which can save you a meaningful amount every month for years. A bigger deposit also shrinks the loan itself, so you pay interest on less. Both effects pull in the same direction. That is why two buyers eyeing the same flat can face very different monthly costs purely because one saved a few thousand pounds more.

There is a floor to consider too. Most lenders want a deposit of at least 5% of the price, so a 95% mortgage is usually the maximum you can borrow against a standard residential purchase. Some buyers go higher than the minimum on purpose to reach a friendlier LTV band.

How deposit and LTV link together

Deposit and LTV are two sides of one sum. If your deposit is 10% of the price, your LTV is 90%. If your deposit is 25%, your LTV is 75%. They always add up to 100%, so the moment you fix one, the other is decided.

The common bands you will see advertised are 95%, 90%, 85%, 80%, 75% and 60% LTV. Sitting just inside a band can matter: a deposit that takes you to 89% rather than 91% may put you in the 90% band and a better rate. If you want to model the borrowing side in detail, the loan-to-value calculator shows the LTV from any deposit and price combination, and our mortgage affordability calculator estimates how large a loan a lender might actually offer you on your income.

How the house deposit calculator works

The maths is simple, and seeing it written out helps you sanity-check any figure the tool gives you. There are two formulas at play.

Deposit needed = property price × deposit percentage. A 10% deposit on a £250,000 home is £250,000 × 0.10 = £25,000. The mortgage you would need is the remainder: £250,000 − £25,000 = £225,000.

Months to save = (deposit still needed − savings you already have) ÷ amount saved each month. If you need £25,000, have £7,000 saved and put away £600 a month, that is (£25,000 − £7,000) ÷ £600 = £18,000 ÷ £600 = 30 months, or two and a half years.

The calculator runs both steps for you and lets you flex the inputs. Raise the deposit percentage and the loan shrinks but the saving target grows. Increase your monthly saving and the timeline shortens. It is a planning tool, so treat the timeline as an estimate: it assumes a steady monthly amount and does not, by default, add interest earned on the savings along the way or assume the asking price rises while you save.

What the deposit does not cover

One important point the basic sum hides: your deposit is not the only cash you need on completion. You also have to budget for purchase costs that sit on top, chiefly the property transfer tax, plus legal fees, searches, surveys and removals. The property tax is a separate tax in each nation, so do not assume one set of rules applies UK-wide. We come back to this in the common mistakes section, because it catches a lot of first-time buyers off guard.

Worked example: a couple saving for their first home in Leeds

Priya and Sam are renting in Leeds and want to buy a £240,000 two-bed. They are aiming for a 15% deposit to reach an 85% mortgage and a better rate than the 90% deals they were first quoted. Here is how the house deposit calculator breaks it down.

• Deposit needed: £240,000 × 0.15 = £36,000.
• Mortgage required: £240,000 − £36,000 = £204,000 (an 85% LTV loan).
• Already saved: £14,000 between them.
• Still to save: £36,000 − £14,000 = £22,000.
• Saving rate: £900 a month combined.
• Time to target: £22,000 ÷ £900 = 24.4 months, so about two years and one month.

Now compare it with a 10% deposit. That would be £240,000 × 0.10 = £24,000, leaving them only £10,000 short and roughly 11 months away. The trade-off is real: the smaller deposit gets them in the door a year sooner, but the 90% mortgage usually carries a higher rate, so they would pay more each month on a larger loan. Modelling both, rather than assuming bigger is always better, is exactly what this tool is for.

A second scenario: a sole buyer in Glasgow

Consider Aileen, buying alone in Glasgow at £180,000 and targeting a 10% deposit. Deposit needed: £180,000 × 0.10 = £18,000. Mortgage: £162,000. She has £6,000 saved and puts away £500 a month, so (£18,000 − £6,000) ÷ £500 = £12,000 ÷ £500 = 24 months. Because the property is in Scotland, her separate land tax bill follows Scottish rules, not the English ones she might read about online.

How long it takes to save a house deposit

The honest answer is: it depends on three things you control and one you do not. You control the target percentage, your monthly saving and any lump sums (a bonus, a gift, an inheritance). What you cannot fully control is house-price movement while you save, which can quietly raise the target if prices climb.

To shorten the timeline without simply waiting longer, the usual levers are:

• Save somewhere that earns interest. A deposit fund sitting in a current account loses ground to inflation. A regular savings account or a cash ISA can add to the pot. You can model this growth with our savings goal calculator, which works backwards from a target and date to the monthly amount required.
• Use a Lifetime ISA if you qualify. First-time buyers aged 18 to 39 can open a Lifetime ISA, and the government adds a 25% bonus on what you pay in, up to set annual and property-price limits. It is one of the few genuine boosts to a deposit, though it comes with rules and withdrawal penalties if used for anything other than a first home or retirement, so read the conditions before relying on it.
• Reconsider the target band. Stretching from a 5% to a 10% deposit can move you into a cheaper LTV band, but only if the rate saving outweighs the extra time spent renting. Run the numbers both ways.

Help to buy a first home

First-time buyers have a few advantages worth folding into your plan. On the tax side, there is relief on the property transfer tax in England, Northern Ireland and Scotland (Wales does not offer a first-time buyer scheme). That relief reduces the cash you need on completion, which indirectly frees up money that can go towards the deposit itself. Our first-time buyer stamp duty calculator works out the relief for an England or Northern Ireland purchase.

Before you commit to a deposit target, it is worth checking what a lender would actually lend you, because there is no point saving for a 15% deposit on a price the bank will not fund on your income. The how much can I borrow calculator gives an income-based estimate of your maximum loan, which you can pair with the deposit figure here to set a realistic price ceiling.

Common mistakes and what to watch

A deposit plan looks straightforward until the real-world edges show up. These are the ones that trip people up most often.

• Forgetting the purchase costs that sit alongside the deposit. The deposit is rarely the only money you hand over. Legal and conveyancing fees, a survey, mortgage arrangement fees and the property transfer tax all land at or before completion. Budget for these separately, or your carefully saved deposit gets raided to cover them.
• Assuming one set of stamp-duty rules across the UK. The transfer tax is genuinely different in each nation: Stamp Duty Land Tax in England and Northern Ireland, Land and Buildings Transaction Tax in Scotland, and Land Transaction Tax in Wales. The thresholds, rates and reliefs differ, so a figure you read for England can be wrong in Scotland or Wales. Always check the rules for the nation you are buying in.
• Overlooking the second-home surcharge. If this is an additional property rather than your only home, an extra surcharge applies on top of the standard transfer tax in every nation. That is more upfront cash, separate from your deposit, and it is easy to miss when budgeting. The second home stamp duty calculator covers this case.
• Letting price rises outpace your saving. If you are saving for two or three years and local prices climb, your fixed percentage target rises in pounds. Build in a little headroom rather than aiming for the exact minimum.
• Counting gifted money without paperwork. Family help, often called a gifted deposit, is common and accepted, but lenders need a signed letter confirming it is a gift, not a loan, and they will check its source. Sort this early so it does not stall your application.
• Treating the saving timeline as a guarantee. The months-to-save figure assumes you hit the same monthly amount every month with no setbacks. Life rarely runs that smoothly, so leave slack.

The other quiet trap is aiming for the smallest possible deposit on principle. A 5% deposit gets you onto the ladder fastest, but it usually means a higher interest rate and, in a falling market, a greater risk of slipping into negative equity. Bigger is not automatically better either, because every extra month renting has a cost. The right answer is the one your own numbers point to.

Disclaimer: These figures are estimates for guidance only and are not personal tax or financial advice. Check current rules and rates with an official source or a qualified adviser before making a decision.

Who should use this calculator

Works out how long it takes to save a deposit, or how much you need to put away each month to hit a target by a date. Fixing the target as a percentage of price is the sensible way to use it, because deposit size drives the mortgage rate, not just the loan amount.

The jump from 5% to 10% is usually the most valuable saving anyone does, because it moves you out of the highest-rate tier. Beyond that, the tiers at 15%, 20% and 25% each improve the rate again. Saving an extra few thousand to cross a boundary can be worth far more over the mortgage term than the sum itself.

What this calculator assumes

• The target is a percentage of the property price entered.
• Monthly saving accrues with interest at the AER set.
• Existing savings count towards the target from the start.
• The price is assumed constant across the saving period.

Limitations — what it does not cover

• House price movement, which can outpace your saving and is the main risk to a long deposit timeline.
• The Lifetime ISA, which adds a 25% government bonus on up to £4,000 a year for a first home — but has a price cap and a withdrawal penalty outside the rules.
• Other buying costs that come from the same savings: stamp duty, legal fees, survey, moving.
• Gifted deposits, which lenders accept with a declaration confirming the money is a gift.
• Tax on savings interest above your Personal Savings Allowance.
• Affordability, which is a separate constraint — see the borrowing calculator.

Related calculators

Once you know your deposit target, line it up against the other numbers in a home purchase. Use the mortgage affordability calculator to gauge the loan a lender might offer, the loan-to-value calculator to see which rate band your deposit reaches, and the savings goal calculator to plan the monthly amount that gets you to your deposit by a set date. For the upfront tax, the first-time buyer stamp duty calculator covers relief on an England or Northern Ireland purchase. You can also read MoneyHelper's guide to how much deposit you need to buy a home for an independent overview.