Deposit savings calculator
How long a deposit actually takes to save, including the buying costs that land on top of it and catch people out.
How this is calculated
The target is the deposit percentage of the price, plus the buying costs, because you need both on completion day and only one of them is usually planned for.
The balance is stepped forward monthly: interest is applied at one twelfth of the annual rate, then the contribution is added.
Interest does less work than people expect over a short horizon. On a three year goal the monthly amount does almost all of it.
The price is held still. In reality it will move while you save, which is the main risk with a long timescale rather than anything in the arithmetic.
Rates used · 2026/27
| Common deposit | 5% to 10% for a first purchase |
| Best rates usually start | at 25% |
| Buying costs | stamp duty, legal, survey, removals |
| Lifetime ISA | 25% government bonus, conditions apply |
Last checked July 2026. Source: HMRC and gov.uk.
Worked example
A 10% deposit on a £250,000 house is £25,000, plus £4,500 of buying costs, so £29,500 in total. With £8,000 saved and £600 a month going in at 4.5%, that takes 2 years 9 months. The buying costs alone add about five months to the wait.
Common questions
Should I include buying costs in the target?
Yes. Stamp duty, legal fees and a survey all land at completion and cannot go on the mortgage, so they have to be saved alongside the deposit.
Is a bigger deposit worth waiting for?
Rates improve at 90%, 85%, 80% and 75% loan to value. Crossing one of those thresholds can be worth more than the extra months cost you.
What about a Lifetime ISA?
It adds a 25% government bonus on up to £4,000 a year for a first home, with conditions on the property price and a withdrawal penalty otherwise. Worth checking before saving elsewhere.
Will house prices outrun my saving?
They might. That is a real risk on a long timescale and is not modelled here, because a house price forecast is not a figure you can enter honestly.