Everyday Tool
Mortgage Overpayment Calculator
Calculate how much interest and time you could save by making extra payments.
Your Mortgage
Compare your current path with a monthly overpayment scenario.
Assumptions
- Calculations assume a repayment mortgage with a fixed rate.
- Only the overpayment types you switch on are included in the scenario.
- Extra payments are applied after the regular payment in the relevant month.
- Results are estimates and may differ from lender-specific rules.
Privacy note: Mortgage calculations run locally in the browser and sensitive figures are not stored by default.
Financial Impact
Side-by-side estimates showing the effect of your monthly overpayment.
Estimated payment
£1,389.58
Interest saved
£0.00
Time saved
0 months
Total paid
£416,874.69
Without overpayments
25 years 1 month
- Total interest
- £166,874.69
- Total paid
- £416,874.69
- Monthly payment
- £1,389.58
With overpayments
25 years 1 month
- Total interest
- £166,874.69
- Total paid
- £416,874.69
- Regular payment
- £1,389.58
No extra payments are active, so this view is acting as a general mortgage overview using your current balance, rate, and repayment setup.
Balance Over Time
A simple comparison of the remaining balance with and without extra payments.
The balance chart is hidden on smaller screens to keep the calculator focused and readable. Use the summary cards and repayment schedule below for the same comparison.
Repayment Schedule
Review how the balance falls over time with your overpayment included.
Year 1
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £11,136.69
- Principal
- £5,538.27
- Balance left
- £244,461.73
Year 2
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £10,882.28
- Principal
- £5,792.68
- Balance left
- £238,669.05
Year 3
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £10,616.16
- Principal
- £6,058.80
- Balance left
- £232,610.25
Year 4
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £10,337.84
- Principal
- £6,337.12
- Balance left
- £226,273.13
Year 5
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £10,046.69
- Principal
- £6,628.27
- Balance left
- £219,644.86
Year 6
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £9,742.20
- Principal
- £6,932.76
- Balance left
- £212,712.10
Year 7
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £9,423.71
- Principal
- £7,251.25
- Balance left
- £205,460.85
Year 8
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £9,090.60
- Principal
- £7,584.36
- Balance left
- £197,876.49
Year 9
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £8,742.15
- Principal
- £7,932.81
- Balance left
- £189,943.68
Year 10
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £8,377.72
- Principal
- £8,297.24
- Balance left
- £181,646.44
Year 11
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £7,996.54
- Principal
- £8,678.42
- Balance left
- £172,968.02
Year 12
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £7,597.85
- Principal
- £9,077.11
- Balance left
- £163,890.91
Year 13
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £7,180.86
- Principal
- £9,494.10
- Balance left
- £154,396.81
Year 14
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £6,744.72
- Principal
- £9,930.24
- Balance left
- £144,466.57
Year 15
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £6,288.50
- Principal
- £10,386.46
- Balance left
- £134,080.11
Year 16
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £5,811.37
- Principal
- £10,863.59
- Balance left
- £123,216.52
Year 17
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £5,312.29
- Principal
- £11,362.67
- Balance left
- £111,853.85
Year 18
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £4,790.29
- Principal
- £11,884.67
- Balance left
- £99,969.18
Year 19
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £4,244.31
- Principal
- £12,430.65
- Balance left
- £87,538.53
Year 20
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £3,673.23
- Principal
- £13,001.73
- Balance left
- £74,536.80
Year 21
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £3,075.94
- Principal
- £13,599.02
- Balance left
- £60,937.78
Year 22
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £2,451.20
- Principal
- £14,223.76
- Balance left
- £46,714.02
Year 23
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £1,797.77
- Principal
- £14,877.19
- Balance left
- £31,836.83
Year 24
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £1,114.31
- Principal
- £15,560.65
- Balance left
- £16,276.18
Year 25
annual- Payments
- £16,674.96
- Overpayments
- £0.00
- Interest
- £399.47
- Principal
- £16,275.49
- Balance left
- £0.69
Year 26
annual- Payments
- £0.69
- Overpayments
- £0.00
- Interest
- £0.00
- Principal
- £0.69
- Balance left
- £0.00
How it works
Overpayments reduce the principal faster, which means less interest builds up across the rest of the mortgage term.
This calculator compares a baseline repayment path with a monthly overpayment scenario, then shows the difference in payoff time, interest, total paid, and the repayment schedule over time. It also supports one-off and recurring annual extra payments.
You can use it as a simple mortgage repayment overview even if you are not planning to overpay yet, then switch on monthly, one-off, or annual extra payments to compare different payoff strategies.
FAQ
This version supports the two most common starting points: entering a remaining term or entering your current monthly payment.
It is intended as a planning tool rather than a lender-exact quotation, so always check the final figures against your lender’s own repayment rules.
If you are unsure whether to enter a remaining term or a monthly payment, use whichever figure you know with the most confidence from your latest mortgage statement.
What this mortgage overpayment calculator is useful for
A mortgage overpayment calculator helps you test whether small or large extra payments could reduce the total interest paid across the life of your mortgage. For many homeowners, even modest regular overpayments can make a noticeable difference over time.
This is useful if you are deciding whether to put spare cash toward the mortgage each month, use a bonus for a lump-sum reduction, or simply check how quickly your balance could fall under different repayment plans.
Because the tool shows both the baseline path and the overpayment scenario, it is also helpful for comparing trade-offs: shorter term versus lower cash flexibility, regular monthly overpayments versus ad-hoc lump sums, or a cautious plan versus a more aggressive payoff goal.
Common ways to use it
- Check how much interest a fixed monthly overpayment could save.
- See whether a one-off bonus or savings lump sum makes a meaningful dent.
- Compare overpaying every month versus making one annual extra payment.
- Estimate how much sooner you could become mortgage-free.
- Plan conversations with a lender or adviser using clearer figures.
Tips for using the calculator more effectively
Start with lender figures
Use the remaining balance, rate, and current repayment from your latest statement where possible. The closer the starting figures are, the more useful the comparison will be.
Model realistic overpayments
Test amounts you could comfortably sustain rather than ideal-case numbers. A smaller consistent overpayment can often be more practical than an aggressive plan that is hard to maintain.
Check lender rules
Some mortgages limit overpayments or charge early repayment fees. Use the calculator for planning, then confirm any lender-specific rules before making real payment changes.
