This mortgage calculator combines power with simplicity. It gives you the information you need to ensure you don’t borrow more than you can afford. And unlike many alternatives it tells you what your monthly payments will be.
It covers interest only, capital repayment mortgages and amortisation.
Just enter a few numbers and it will tell you:
- What your monthly payment will be (every one of them!)
- How those payments split between interest and repayment
- The total interest you’ll pay
- How much you pay back to the bank altogether
- And how much your property really cost!
That last point is worth explaining.
Many people mistakenly believe they paid the sale price for their property when in actual fact they usually pay far more than that when mortgages are involved.
Mortgages mean interest and interest means more money. Sometimes, a lot more!
The calculator gives you a lot of information, but perhaps the most important thing you’ll learn is how much your mortgage increases the price you end up paying for a house.
The interest rate you pay essentially determines the price you pay for your house. Lower the interest rate, lower the house price. Which is why oftentimes it really does pay to find yourself a good mortgage broker.
Here’s the calculator, but see below for a guide where we go into a bit more detail.
(If you are reading this on your mobile phone please choose ‘Exit mobile version’ at the bottom of the page to use the calculator).
Mortgage payment monthly calculator
Basic vs advanced functionality
Our calculator spits out many numbers. Some are basic. Some are more advanced. But don’t worry if you are after a simple number. Just look for that one. All the results are explained below. You don’t need to know what they all mean. Understand the one or two that are important to you and you are good to go.
Interest rate, house price, deposit, term and start date as inputs
Interest rate, house price, deposit, term and start date are all possible inputs.
5 simple variables that provide essential information when you crunch the numbers.
You get answers to 5 key questions.
- What your monthly payment will be (every one of them!)
- How those payments split between interest and repayment
- The amount of interest you’ll pay in total
- How much you pay back to the bank altogether
- And how much your property really costs!
House Price
You could just put your house price here, but there are a few other options that you could enter to increase accuracy. These are the main ones.
- House price
- House price minus discount
- House price plus fees
- House price minus discount plus fees
Deposit
This is the amount of money you put into the deal yourself. Not only does the size of your deposit determine how much you borrow, but it can also determine how much interest you need to pay.
People often talk about this in terms of Loan to Value ratio or LTV. This is a simple concept.
Say you put down £10K for a property worth £100K and get a mortgage for the remaining £90K.
Your LTV would be 90%.
If you had borrowed £75K your LTV would be 75%.
All things being equal, the smaller the LTV the less interest you pay and the less you’ll end up paying for your house.
Common LTVs in the UK are 90%, 75% and 60%. But 100% is possible for some types of buyers some of the time.
Mortgage term
This is the number of years you want to mortgage for. In theory it could be any length of time up to 40 years, but the standard is 25.
Interest rate
Most people think about buying a house in simple terms. Can I afford the repayments? They don’t think about how much this house is really costing over the long term.
Don’t get me wrong. People can be forgiven for this when it comes to their dream home. Paying over the odds to live in a better place can often be worth it. But not in financial terms.
People tend to fall down by mistaking their dream home for a great investment, when oftentimes it was anything but. (We’ve talked more about this here).
If you want to understand the financial implications of any property purchase, it’s usually a good idea to focus your attention on interest rates.
They are based on the Bank of England base rates and they are critical to determining how much a mortgage ends up costing you.
Have a look at the table below. It compares the impact of different interest rates on a £300K house bought with a 75% LTV repayment mortgage.
| Interest rate % | Monthly Repayments £ | Total interest £ | How much your house really cost you |
| 1 | £848.00 | £29,000.00 | £329,000.00 |
| 3 | £1,067.00 | £95,000.00 | £395,000.00 |
| 5 | £1,315.00 | £170,000.00 | £470,000.00 |
| 7 | £1,590.00 | £252,000.00 | £552,000.00 |
Even with a 1% interest rate your house still ends up costing 10% more than you thought it did. By the time we’ve got up to 7% you end up paying close to double.
And by the way, the difference would be even greater for interest only mortgages.
We’ve gone into a lot more detail about the differences between fixed rate, variable rate and tracker mortgages here, but in short, all but fixed rates can change from month to month.
And just in case you are thinking… “but not from 1-7%.” You’d be wrong! That happened to me in just over a year in 2022/2023. If only I’d had a fixed rate! But even then only luck would have stopped the need to renegotiate at around that time. (That’s a topic for another day)
Start date
If you enter a start date you get a repayment schedule. This shows each an every mortgage payment you make for a repayment mortgage.
Though the overall amount remains pretty constant, the split between interest and capital changes over time due to amortisation. (See Repayment Mortgage Calculator Amortisation below for more details about this).
Amortisation
With this calculator you get to see a repayment schedule when you click calculation.
You are given a breakdown of your monthly payments. This let’s you visualize the split between interest and capital repayment. You also get to see the impact of amortisation.
Amortisation describes the way in which the amount you borrow decreases after each payment you make.
Though your monthly repayment remains pretty constant, the breakdown between interest and capital repayment changes.
Amortisation is important for capital repayment mortgages. But not for interest only where’s there’s nothing to break down. You just pay a fixed amount of interest with those.
On the other hand, with a repayment mortgage part of your payment goes towards paying interest and the other to repaying the capital you borrowed from the bank. And the important thing is that this changes over time.
When you begin your repayments a much larger portion goes towards paying the interest. This reduces gradually over time.
In the later stages this split is reversed and more of your money will go to paying back the capital you borrowed.
Repayment schedule
The repayment schedule shows how this breaks down.
You get to see how much of your monthly payment goes towards paying off interest and how much goes to repaying capital.
For example if I borrowed £225K at 5% my monthly payments would be £1315.33/month. They would break down as follows:
In the first month I would pay £377.83 back to the bank (Payment to Principle) leaving the remainder, £937.50 for interest. In other words, most of that first payment goes to interest.
However, this reduces over each and every payment until it’s just over a fiver in interest for the final one.
Interest only
You can crunch the numbers for both repayment and interest only mortgages.
With interest only your monthly payments just cover interest. You don’t need to pay off the money you borrowed from the bank until the end of the mortgage term.
And there’s a major advantage with this approach. The monthly repayments are lower. Oftentimes, a lot lower.
Disadvantages of interest only mortgages
There are a couple of major disadvantages with interest only, though.
First, you end up paying more for the same property overall. That’s because there’s no amortisation with interest only mortgages. You don’t pay off the loan over time so the interest payments remain the same.
Second, you have to find the money to pay off the sum you borrowed at the end of the term. Repayment mortgages let you nibble away at your borrowings gradually over time. You don’t have to think about it. With interest only it’s up to you to find the money.
Buy to let (BTL) landlords prefer this type of mortgage. Though they do appreciate capital gains, landlords usually need a surplus between the amount of rent their tenants pay and their mortgage repayments.
It’s harder to get that surplus with repayment mortgages because the monthly payments are higher.
Landlords assume they’ll sell the house or remortgage at the end of the term and make a nice profit with capital gains. And whilst in many cases, that works great, now and again it doesn’t.
Nobody knows what the future holds. Bad tenants, housing market crashes and the like can lay waste to even the best laid plans.
The bottom line being, interest only mortgages come with more risk and more costs over the long term but lower monthly repayments mean you can grow your portfolio and consequently wealth faster.
Monthly payment
Monthly payments are given for both interest only and repayment so you can compare the two.
Total interest
The total amount of interest you end up paying is calculated for both interest only and repayment mortgages.
Total to pay to the bank
The total to pay to the bank includes the interest and capital.
Total to pay (How much is this house really costing you!)
Total to pay includes the interest you pay, the capital you need to repay to the bank that you borrowed and your deposit.
Example mortgage calculations
We’ve included a few examples just in case you want to run some test numbers. All assume a £300K house is bought over a 25 year term and the numbers are rounded.
Example 1 – 100K mortgage interest only 6%
- Your monthly payment is £500.
- The total interest you pay is £150K
- The total you pay back to the bank is £250K
- The total you pay for the house including the deposit is £450K
Example 2 – 100K repayment 6%
- Your monthly payment is £644
- The total interest you pay is £93K
- The total you pay back to the bank is £193K
- The total you pay for the house including the deposit is £393K
Example 3 – 200K mortgage interest only 5%
- Your monthly payment is £833
- The total interest you pay is £250K
- The total you pay back to the bank is £450K
- The total you pay for the house including the deposit is £550K
Example 4 – 200K mortgage repayment 5%
- Your monthly payment is £1,169
- The total interest you pay is £151K
- The total you pay back to the bank is £351K
- The total you pay for the house including the deposit is £451K
Mortgage payment monthly calculator – the bottom line
So there you have it. Our mortgage calculator crunches the numbers so that you don’t have to.
It covers interest only and capital repayment mortgages. And it shows you what you pay each and every months throughout the term.
The key takeaways being the lower your interest rate the less you pay for your house.
And I guess, the best way to lower your interest rate is to find a good mortgage broker.