House Buying Costs Calculator
This house buying costs calculator works out your likely monthly mortgage payment. Enter the home price, the down payment you plan to make, the interest rate (APR) and the term in years. It shows the amount you would borrow, the monthly payment for principal and interest, and the total interest paid over the term.
If you know your annual property tax, home insurance or monthly HOA fees, you can add them too. The calculator then adds them to the monthly figure so you can see a fuller picture of your regular housing cost. Every figure is simple arithmetic on the numbers you enter, so the result is only as accurate as your inputs.
Year-by-year schedule
How to use the house buying costs calculator
- Enter the home price in pounds.
- Enter the down payment you intend to put in. The calculator subtracts this from the price to find the amount borrowed.
- Enter the interest rate (APR) as a percentage and the mortgage term in years.
- If you have them, enter your annual property tax and home insurance, and any monthly HOA fees. Leave these blank if they do not apply.
- Read the monthly payment, the principal and interest, the amount borrowed and the total interest. Check the figures with your lender before making decisions.
The formula
- Amount borrowed = price − down payment
- Monthly payment = P × r ÷ (1 − (1 + r) ^ −n), where P is the amount borrowed, r the annual rate ÷ 12 ÷ 100 and n the number of months
- Monthly payment = principal and interest + property tax ÷ 12 + insurance ÷ 12 + HOA per month
Worked example
The figures below are made up to show the maths. They are not current prices, rates or product figures.
| Home price | £350,000.00 |
|---|---|
| Down payment | £70,000.00 |
| Interest rate (APR) | 6.5% |
| Term | 30 years |
- Monthly payment £1,769.79
- Principal and interest £1,769.79
- Amount borrowed £280,000.00
- Total interest £357,124.57
Tips for an accurate answer
- Use the rate you have actually been quoted, not a guess, because small changes in the rate shift the monthly payment noticeably.
- Remember that the total interest figure covers the whole term, so a longer term lowers the monthly payment but raises the total you pay.
- Property tax and insurance can change over time, so treat the monthly figure as an estimate rather than a fixed cost.
- Add any HOA or service charges so the monthly total reflects everything you would pay each month.
- Ask your lender or bank to confirm the exact payment, fees and any extra costs before you commit.
Questions people ask
How much house can I afford in the UK?
This calculator does not decide what you can afford, because that depends on your lender's criteria and your own finances. It shows the monthly payment for a price, deposit, rate and term you enter, so you can test different scenarios. Speak to a lender or mortgage adviser for an affordability assessment.
How do I calculate how much I need for a house?
Enter the home price and the down payment you plan to make, and the calculator shows the amount you would need to borrow. Adding the rate, term and any regular costs shows the monthly amount involved. Check the results with your lender for the full sum you need.
Can I use this house buying costs calculator for a London purchase?
Yes, the calculator works with any home price you enter, wherever the property is. It does not use local prices or rates, so enter the figures for the specific property you are considering.
Can I use this calculator for a Manchester property?
Yes. Enter the price, deposit, rate and term for the Manchester property you are looking at, and the calculator will work out the monthly payment from those figures.
What does this calculator actually work out?
It calculates the monthly mortgage payment for principal and interest, using the amount borrowed, the interest rate and the term. It also shows the total interest paid over the full term.
Does the monthly payment include everything I pay for the house?
Only if you enter your property tax, home insurance and HOA fees. Without them, the figure covers the mortgage alone and leaves out other regular costs.
How is the amount borrowed worked out?
The calculator subtracts the down payment from the home price. The result is the amount you would need to borrow from the lender.
Why does the total interest look so large?
Interest is charged over every month of the term, so over a long term the total can be much larger than the amount borrowed. The worked example on the page shows this clearly.
Sources
This calculator uses the standard loan and interest formulas above and the numbers you type. It needs no outside figures.
An estimate from the numbers you enter, worked out with the formula shown. It is maths, not financial advice: your lender or bank has the final figures. Page checked 23 Oct 2026. Read the disclaimer