About this calculator
Most overpayment calculators focus on interest saved over the full term. This one focuses on something more immediately useful: what LTV you will be at when your fixed deal ends, and whether a bit of overpaying now could move you into a cheaper rate bracket.
When your fixed rate expires, your lender prices your new deal based on your loan-to-value ratio at that point. UK lenders work in bands - typically 60%, 65%, 70%, 75%, 80%, 85% and 90% LTV. Crossing from one band into a lower one can unlock a noticeably better rate, sometimes worth thousands over your next fixed term.
The question this calculator answers is simple: how much do you need to overpay - monthly or as a lump sum - to cross that threshold by the time your deal ends?
Your loan-to-value ratio is your outstanding mortgage balance as a percentage of your property's current value. Owe £180,000 on a home worth £250,000, and your LTV is 72%.
UK mortgage lenders use LTV bands to price their deals. The lower your LTV, the less risk for the lender, and the better the rate on offer. The key thresholds to know are:
| LTV bracket | What it means for your rate |
|---|---|
| 60% or below | Best rates on the market - you own at least 40% of your home |
| 60-65% | Near-best rates, a small step up from 60% |
| 65-70% | Competitive rates, plenty of lenders to choose from |
| 70-75% | Good range of products still available |
| 75-80% | Rates start to climb noticeably |
| 80-85% | Fewer lenders, higher rates |
| 85-90% | Limited products, significantly higher rates |
Worth understanding: going from 76% to 74% LTV - crossing the 75% boundary - can make a bigger difference to your rate than going from 80% to 76% within the same band. It is not a smooth curve, it is a step change.
Every overpayment reduces your outstanding balance faster than your standard repayment schedule would. So by the time your fixed deal ends, your balance is lower, your LTV is lower, and you may qualify for a better rate band.
Most UK fixed-rate mortgages let you overpay up to 10% of your outstanding balance each year without triggering an early repayment charge. Tracker and variable rate mortgages usually have no such limit. Always worth checking your mortgage offer document before overpaying.
You can overpay in two ways: a regular extra amount each month, which chips away at the balance steadily; or a one-off lump sum, which reduces it straight away. Both options are in the calculator above.
Common questions
Click any question to expand the answer.
It depends on your current balance, property value, interest rate, and how long you have until your remortgage date. Enter your details in the calculator, set your remortgage date, and drag the slider until the LTV bar shows you crossing into the 70-75% bracket. The slider shows the exact monthly or lump sum figure needed to get there.
Only if it moves you across a bracket boundary. If you are heading for 76% LTV at remortgage, paying enough to get to 74.9% could unlock the sub-75% rate tier. If you are already sitting comfortably inside a band, overpaying will still save you interest over the full term - it just will not change which rate band you are offered at remortgage.
Most UK fixed-rate mortgages let you overpay up to 10% of your outstanding balance each year without an early repayment charge (ERC). On a £200,000 mortgage that is £20,000 a year, penalty-free. The limit usually resets annually. Go over it and ERCs of 1-5% of the excess may apply. Check your mortgage offer document for the exact terms on your deal.
The numbers-only answer: compare your mortgage rate to the savings rate you can actually get. If your mortgage rate is higher, overpaying wins mathematically. If savings rates are better, you might be better off saving. But the LTV angle changes things a bit - if overpaying would move you into a lower bracket at remortgage, the rate saving you would get could tip the balance in favour of overpaying even when savings rates are competitive.
With most UK lenders, overpayments reduce your balance and by default shorten your term rather than cutting your monthly payment. Some lenders give you the choice. Shortening the term means you are mortgage-free sooner and pay less total interest. The calculator models term reduction, which is the more common and usually more financially beneficial outcome.
It is your outstanding mortgage balance on that date divided by your property's current value, as a percentage. Your property value may have changed since you bought - if your home has gone up in value, your LTV is already lower than when you started, even without any overpayments. You can test different property value scenarios in the calculator by adjusting that field.
Good news if it has - your LTV is already lower than it was when you took out the mortgage. Enter your current estimated property value in the calculator to see where that puts you. Even modest house price growth can nudge you across an LTV threshold. You might find you are already closer to the next bracket than you thought, and only a small overpayment would get you there.
Remortgage Lens is a planning tool to help you think through the impact of mortgage overpayments on your LTV at remortgage. It is not financial advice. Calculations assume a fixed interest rate for the period modelled and do not account for early repayment charges, lender-specific rules, or future changes in property value. Speak to a qualified mortgage adviser before making overpayment decisions.