When Will My Mortgage Be Paid Off? How to Work Out Your Mortgage-Free Date
The end date printed on your mortgage statement is only a forecast. It assumes today’s rate lasts for the whole term and that you never pay a penny extra. Here is how the calculation actually works, why the balance barely moves in the early years, and how much sooner £100 to £500 a month of overpayments would make you mortgage-free.
Published: 29 September 2026 at 09:00 · 7 min read
The Short Answer
Your mortgage-free date is set by three things: the balance you owe, the interest rate, and how much you pay each month. Change any one and the date moves. A £200,000 repayment mortgage at 4.5% over 25 years costs £1,112 a month and is cleared in exactly 25 years, with about £133,500 of interest along the way. Overpay £100 a month and it is gone in 21 years 6 months. Overpay £500 a month and you are mortgage-free in 14 years, saving roughly £63,900 of interest.
If you only want the date, your annual statement gives it. If you want to know how to bring it forward, read on, or go straight to our mortgage overpayment calculator and enter your own balance, rate and payment.
How Do I Calculate When My Mortgage Will Be Paid Off?
You need three numbers, all on your latest mortgage statement or in your lender’s app:
- Outstanding balance — what you owe today, not what you originally borrowed.
- Interest rate — your current deal rate. Divide by 12 to get the monthly rate, so 4.5% becomes 0.375%.
- Monthly payment — the contractual payment plus any regular overpayment you make.
The number of months left is then:
Take someone seven years into a mortgage with £160,000 left at 4.5%, paying £1,000 a month. Monthly rate 0.00375 × £160,000 = £600, divided by £1,000 = 0.6. One minus 0.6 is 0.4, and −ln(0.4) is 0.916. Divide by ln(1.00375), which is 0.003743, and you get 245 months, or 20 years 5 months. Pay £1,200 a month instead and it drops to about 15 years 5 months. Pay £1,500 and it is 11 years 4 months.
One warning built into the formula: if your payment is less than the monthly interest (here, less than £600) the loan never clears. That is what an interest-only mortgage looks like in the maths, and why those borrowers need a separate repayment plan.
Why Does the Balance Fall So Slowly at First?
Interest is charged on the whole outstanding balance, so early payments are mostly interest. On £200,000 at 4.5%, the first £1,112 payment contains £750 of interest and just £362 of capital. As the balance shrinks the interest shrinks with it and the capital share grows. This is the principal versus interest curve, and it explains why the balance looks stuck for years:
| Years into a £200,000, 25-year mortgage at 4.5% | Total paid so far | Balance remaining | Share of loan cleared |
|---|---|---|---|
| 5 | £66,700 | £175,700 | 12% |
| 10 | £133,400 | £145,300 | 27% |
| 15 | £200,100 | £107,300 | 46% |
| 20 | £266,800 | £59,600 | 70% |
| 25 | £333,500 | £0 | 100% |
After ten years you have handed over £133,400 and cleared only just over a quarter of the loan. The second half of the mortgage clears far faster than the first. The upside is that every pound overpaid early goes straight to capital and stops earning the lender 4.5% for the rest of the term, which is why early overpayments move the date so much.
How Much Do Overpayments Bring the Date Forward?
Same £200,000 mortgage, 4.5%, 25 years, £1,112 a month. Overpayments start from month one and the contractual payment stays the same:
| Monthly overpayment | Mortgage paid off in | Earlier by | Total interest | Interest saved |
|---|---|---|---|---|
| £0 | 25 years | — | £133,500 | — |
| £100 | 21 years 6 months | 3 years 6 months | £112,400 | £21,100 |
| £200 | 18 years 11 months | 6 years 1 month | £97,200 | £36,300 |
| £300 | 16 years 11 months | 8 years 1 month | £85,800 | £47,700 |
| £500 | 14 years | 11 years | £69,600 | £63,900 |
| £1,000 | 9 years 10 months | 15 years 2 months | £47,500 | £86,000 |
Notice the diminishing returns. The first £100 buys 3½ years; the fifth £100 buys about 1½ more. That is not a reason to stop, but it does mean the case for switching spare cash from overpayments into an ISA gets stronger as the overpayment grows. We compare the trade-off in pay off the mortgage or invest.
A one-off lump sum works the same way. Putting £10,000 in at the start of that mortgage clears it 2 years 2 months early and saves about £19,300. See lump sum vs monthly overpayments for the full comparison, and check the 10% annual limit on most fixed deals in how much can I overpay.
Mid-mortgage: what if you are already years in?
Most readers are not at month one. Take £160,000 left with 18 years to run at 4.5%, a payment of £1,082. Overpaying £100 clears it in 15 years 10 months (2 years 2 months early, £10,000 saved). £200 makes it 14 years 1 month (3 years 11 months early, £17,600 saved). £500 makes it 10 years 8 months, 7 years 4 months early, saving £32,200. The years saved are smaller than at the start because less interest is left to avoid, but the effect is still substantial.
Why the Date on Your Statement Keeps Moving
Three things push the date around even if you never overpay:
- Rate changes. When a fix ends, the lender recalculates the payment over the remaining term at the new rate. The end date normally stays put, but the payment rises or falls. If you keep paying the old, higher amount after a rate cut, the date comes forward.
- Remortgaging onto a new term. Moving to a new lender on a fresh 25-year term resets the clock unless you deliberately match the remaining years. A borrower who remortgages every five years on 25-year terms never finishes.
- Reducing the payment after an overpayment. Some lenders default to lowering your monthly payment after a lump sum, which keeps the original date. Ask for the term to be reduced instead if the date is what you care about. We cover this choice in reduce the term or the payment.
The interest rate matters less to the years saved than you might expect. Overpaying £200 a month on £200,000 over 25 years brings the date forward by 5 years 11 months at 3%, 6 years 1 month at 4.5% and 6 years 4 months at 6%. The money saved swings far more: £21,600, £36,300 and £54,100 respectively. So a higher rate does not change your plan much in time, but it makes each overpayment worth more.
How Does the Mortgage-Free Date Fit a FIRE Plan?
For most UK FIRE pursuers the mortgage is the biggest fixed cost, so its end date and the retirement date are linked. At a 4% withdrawal rate, every £1,000 a year of spending needs about £25,000 invested. A £1,112 monthly payment is £13,340 a year, which adds roughly £333,600 to your FIRE number for as long as it lasts. Clearing the mortgage before you stop work removes that entire chunk.
That does not always mean overpaying is right. Cash in a Stocks & Shares ISA compounding at 6% or 7% can outgrow a 4.5% mortgage over 15 to 20 years, and a higher-rate taxpayer gets 40% relief on pension contributions that no overpayment can match. A common compromise is to aim the mortgage-free date at your planned retirement date, with an overpayment sized to hit it, and to invest everything above that. Our guide to overpayments and your FIRE date runs the numbers both ways, and retiring with a mortgage covers the case where the two dates do not line up.
Whatever you decide, keep an emergency fund outside the house first. Overpayments are hard to get back, and a mortgage-free date brought forward by two years is no comfort if a boiler failure ends up on a credit card.
Frequently Asked Questions
How do I calculate when my mortgage will be paid off?
Take your current balance, your interest rate and your monthly payment from your latest statement. The number of months left is: minus the natural log of (1 minus the monthly rate times the balance divided by the payment), divided by the natural log of (1 plus the monthly rate). For a £160,000 balance at 4.5% (0.375% a month) with a £1,000 payment, that is about 245 months, or 20 years 5 months. Most people find it easier to use a mortgage overpayment calculator, which does the same sum and lets you add overpayments.
Is the end date on my mortgage statement accurate?
Only if your rate never changes and you never overpay. The statement date assumes your current rate lasts for the whole remaining term. When a fixed deal ends and you remortgage, the lender recalculates your payment over the remaining term, so the date usually stays the same but the payment moves. Overpaying with the payment kept the same brings the date forward; reducing the payment instead leaves the date where it is.
How much sooner will my mortgage be paid off if I overpay £100 a month?
On a £200,000 mortgage at 4.5% over 25 years (£1,112 a month), overpaying £100 a month clears it 3 years 6 months early and saves about £21,100 of interest. £200 a month brings the date forward by 6 years 1 month and saves £36,300. £500 a month clears it in 14 years, 11 years early, saving £63,900. The effect is largest early in the term, when most of each payment is interest.
Why does my mortgage balance fall so slowly in the first few years?
Because interest is charged on the whole outstanding balance, the early payments are mostly interest. On £200,000 at 4.5%, the first £1,112 payment includes £750 of interest and only £362 of capital. After five years you have paid about £66,700 but the balance has only fallen to £175,700. The split flips over time: by the final years almost every payment is capital. This is why overpayments made early in the term save the most.
Should my mortgage be paid off before I reach FIRE?
It is not essential, but it makes the maths simpler. Every £1,000 of annual spending needs roughly £25,000 invested at a 4% withdrawal rate, so a £1,112 monthly payment adds about £333,600 to your FIRE number for as long as it lasts. Many UK FIRE pursuers aim to line up the mortgage-free date with, or slightly before, their planned retirement date. Others keep a cheap mortgage and invest instead. Compare the two paths with a FIRE number calculator before deciding.
Work Out Your Own Numbers
Grab your latest statement for the balance, rate and payment, then model your own mortgage-free date:
- Mortgage Overpayment Calculator — enter your balance, rate and term, add a monthly or lump-sum overpayment, and see the new payoff date and interest saved
- Mortgage Principal Calculator — see how much of each payment goes to capital versus interest, and how the balance falls year by year
For the wider picture, read our mortgage overpayment calculator guide and what £100, £200 or £500 a month really saves.
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