Tools

Deposit Needed for the Next Price Band

Mortgage pricing steps down at loan-to-value boundaries rather than sliding. How much more deposit reaches the next band, and what is that band worth once the smaller loan is taken out of the answer?

A lender does not price a mortgage on a sliding scale. It prices in bands, so an extra pound of deposit changes nothing at all across most of the range and changes the whole rate at a boundary. This page takes the ladder you are actually looking at and says two things: how far your deposit is from the next step down, and what that step is worth per month — held apart from what the smaller loan is worth, which is the larger half and has nothing to do with the boundary.

What this tool does not decide

Whether to stretch for a band. Reaching a boundary means finding money from somewhere, and where it comes from — savings, an emergency fund, family, a delayed purchase — is what decides whether it is worth doing. None of that is here.
Who to borrow from. This tool ships no band table, names no lender, broker, product or country, fetches nothing and has no field to name one with. The bands are yours to enter, and that is why nothing on this page can go out of date.
Whether anyone would lend to you. A ratio sitting inside one of your bands is a row in your table, not an offer. "No band prices this" means your own ladder stops short of your ratio — not that nobody would lend.
What the mortgage would actually cost. A rate held for a whole term is not how most mortgages work, and fees, mortgage insurance and purchase taxes are all outside this arithmetic. They are listed in the methodology rather than summarised away.
Anything about tax, in any jurisdiction.

Your figures

The interactive calculation runs in your browser and needs local JavaScript, which is currently switched off. Activating the Calculate button does nothing at all: no request is sent and nothing is submitted.

Everything else on this page works without it. The model, the formulas, the timing convention, the worked example, the assumptions and the limitations are all in the methodology below, and the companion explainer covers the mechanism in full.

Your figures, and your lender's bands

Three numbers about the purchase, and the price ladder you are actually looking at. Nothing is sent anywhere, nothing is stored, and no lender, product or market rate is looked up.

The price of the property

What you are paying for it. Every band is a proportion of this figure, so it is what turns a ratio into a deposit.

The deposit you have

What you can put in today. Enter 0 if you have none yet — the answer is then the whole distance to the first band you could reach.

The term

How long the loan runs, in years. It may be fractional, and the schedule is monthly. A longer term makes every payment smaller and makes the step worth less per month and more in total.

The band table

The bands are yours to enter and this page ships none. Lenders price at different boundaries, they move them, and the rate inside a band changes week to week — a table published here would be out of date before it was read, and would quietly become a recommendation about who to borrow from. Copy the ladder from the lender, the broker or the comparison you are actually looking at. Nothing you type is sent anywhere.

Five rows, and you need at least two. Leave a row completely blank if you do not need it — a row with only one half filled in is refused rather than quietly dropped. If your lender has a longer ladder, enter the part of it around where you stand: the answer depends on the band you are in and the one below it, and on nothing else.

Band 1 — highest loan-to-value it prices

The top of the band, as a percentage of the price. 80 means a band that runs up to eighty per cent. A loan sitting exactly on a ceiling is inside that band.

Band 1 — the annual rate it prices at

The rate this band charges, as an annual percentage. Enter it exactly as the ladder states it; this page does not check that rates fall as the ceiling falls, because a table where they do not is either a copying slip or a lender that prices that way, and it has no basis for deciding which.

Band 2 — highest loan-to-value it prices

Band 2 — the annual rate it prices at

Band 3 — highest loan-to-value it prices

Band 3 — the annual rate it prices at

Band 4 — highest loan-to-value it prices

Band 4 — the annual rate it prices at

Band 5 — highest loan-to-value it prices

Band 5 — the annual rate it prices at

Result

Putting in more deposit does two different things at once, and they are almost always reported as one number. It makes the loan smaller, which lowers the payment at any rate at all — that saving is just owing less money, and you would get it from any extra deposit anywhere in the range. And at a boundary it also moves you into a cheaper band, which lowers the rate. Only the second one is what the band is worth. This page publishes the two separately and never publishes the total without them, because a figure that added them together would credit the boundary with a saving most of which was nothing to do with it.

Enter your figures and your bands above, then select Calculate. Nothing is sent anywhere: the calculation runs in this browser, and no value is stored, shared or placed in the address bar.

The loan you would take at that deposit: Not yet calculated
Your loan-to-value ratio now: Not yet calculated
The rate your own table prices that at: Not yet calculated
The monthly payment on that loan, at that rate: Not yet calculated
The deposit that reaches the next band: Not yet calculated
How much more deposit that is: Not yet calculated
The rate the next band down prices: Not yet calculated
The size of the step, in percentage points: Not yet calculated
Monthly saving from the smaller loan alone, at your current rate: Not yet calculated
Monthly saving from the lower rate — this is what the band is worth: Not yet calculated
The two together, per month: Not yet calculated
Total paid over the term, as you are: Not yet calculated
Total paid over the term, after the step: Not yet calculated

Every payment here is a level monthly repayment that clears the loan to zero over whole months, at the annual rate you entered for that band, convertible monthly. It is comparable with another payment worked out the same way and with nothing else. It is not a quotation, it is not an offer, and it is not what a lender would actually charge you: a real illustration carries fees, a fixed period that ends, and an assessment of you that this page knows nothing about.

This is arithmetic on a price, a deposit, a term and a table you typed. It assumes the rate you entered for a band applies for the whole term, which is almost never true — most rates are fixed for a period and then revert — and it assumes nothing else is added along the way. The step it prices is the step your own table describes, so a table copied wrongly produces an answer that is exactly as wrong and gives no sign of it.

A distance and a saving are not a verdict. Reaching a boundary means finding money from somewhere, and where it comes from is the part that decides whether it is worth doing: a deposit stretched from an emergency fund, a family loan or a delayed purchase costs something this page cannot see and does not price. It also says nothing about whether any lender would lend to you at any ratio at all. A ratio inside a band is a row in your table, not an offer.

How this is worked out

Why mortgage pricing is a staircase rather than a slope

A lender does not price your loan as a smooth function of how much you are borrowing against the property. It prices in bands: everything up to some ratio costs one rate, everything up to the next ratio costs another.So an extra pound of deposit is worth almost nothing across the whole of a band, and worth a complete change of rate at a boundary. That is the mechanism, and it is why "what is my loan-to-value" — which every calculator answers — is not the question. The question is how far you are from the next step down, and what that step is worth.

The two things extra deposit does, and why they must not be added

Here is the part that gets reported as one number and is really two. Putting in more deposit makes the loan smaller, which lowers the payment at any rate whatever. At a boundary it also makes the rate lower. Only the second is what the band is worth, and in an ordinary ladder it is much the smaller half — so a figure that added them together would credit the boundary with a saving most of which was nothing to do with it.

Three payments, and the middle one is not an arrangement anybody is offered. It is what separates the deposit's effect from the band's.
Payment	On which loan	At which rate	Why it is here
What you pay now	The loan you have	The rate of the band you are in	Where you start
The same loan the next band would price, at your current rate	The smaller loan	Still the rate of the band you are in	Nobody offers this. It is the separator, and it is the only way to see which half of the saving is the band
What you would pay in the next band	The smaller loan	The rate of the band below	Where you end up

From the smaller loan: The first payment less the second. You would get this from the same extra deposit at any ratio anywhere in the range, boundary or no boundary — it is simply owing less money
From the lower rate: The second payment less the third. This is the whole of what the boundary earns, and it is the figure this page leads with
The two together: Their sum, and never the difference between the first payment and the third. Computing it both ways and publishing one would let a rounding disagreement hide inside the decomposition

The arithmetic

The loan is the price less the deposit, and the ratio is the loan divided by the price. The band that prices it is the one with the smallest ceiling at or above that ratio. The deposit that reaches the next band is the price times that band's ceiling, subtracted from the price — a level, not a difference — and how much more you need is that level less what you have.

L = P − D            v = L ÷ P            band(v) = the smallest ceiling c with c ≥ v

pay(L, r) = L · i ÷ (1 − (1 + i)^−m)            i = r ÷ 12            m = round(12 · years)

The payment is a level monthly amount that clears the loan to zero over m whole months. At a rate of exactly zero it is the loan divided by the months, which is a genuine case rather than a guard — the general expression divides by the monthly rate.

What you enter, and what this page will never enter for you

A price, a deposit, a term and the band table you are looking at.This page ships no bands and names no lender. Boundaries differ between lenders, they move, and the rate inside a band changes week to week — a ladder published here would be stale before it was read and would quietly become a recommendation about who to borrow from. Because it holds no such fact, there is nothing on this page that can go out of date.

Five rows are offered and two are the minimum. If your lender's ladder is longer, enter the part of it around where you stand: the answer depends on the band you are in and the one below it, and on nothing else.

The limits this calculation imposes on itself

The rate you enter for a band is assumed to apply for the whole term. Almost no mortgage works that way — most rates are fixed for a period and then revert — so every payment here is a comparison between two rates rather than a forecast of what you will pay.
The band that prices a ratio is the one with the smallest ceiling at or above it, so a loan sitting exactly on a ceiling is inside that band rather than the one above.
The price, the deposit and every payment are in the same unit, and every ratio is invariant in it.
A table whose rates rise as the ceiling falls is not refused. The step is reported as the negative number it is, because this page has no basis for deciding whether such a table is a copying slip or a lender that genuinely prices that way.
Nothing here is conditional on any lender, broker, product or country, and no figure below describes a market.

What is not modelled

any arrangement, booking, valuation or broker fee, which are often larger at lower ratios
a rate that is fixed for a period and then reverts to something else, which is most of them
whether any lender would lend to you at any ratio, which depends on income, credit and the property
stamp duty, land tax or any other purchase cost, in any jurisdiction
mortgage insurance or a guarantee charged at higher ratios
what the money used for a larger deposit would otherwise have done
overpayments, early repayment charges, or paying the loan off before the term ends
the identity of any lender, broker, product or country
tax, in any jurisdiction

The mechanism behind the decision — why committing more money here can only be judged against what the same money would have done elsewhere — is taught in the explainer:how to compare two financial uses of money.

Go deeper

The nearest published mechanism
How to Compare Two Uses of Money Without Fake Certainty
Why opportunity cost only exists relative to a real alternative, what makes a comparison like-for-like, why a higher annual rate can start behind, and why the option that ends higher is not automatically the one to choose.
This page prices what an extra pound of deposit buys at a boundary. Whether that is the best thing that pound could do is a comparison against something else, and the explainer is about how to make one honestly.
Read the explainer: How to Compare Two Uses of Money Without Fake Certainty

Calculation model and corrections

Calculation model: Deposit Band Step v1.0
Last reviewed: 27 August 2026
What the band is worth: The difference between the payment on the smaller loan at your current rate and the payment on the same loan at the lower rate. It is the only figure here that the boundary itself earns
What the deposit is worth: The difference between the payment you have now and the payment on the smaller loan at the same rate. You would get it from that extra deposit whether or not it crossed a boundary, which is why it is published separately
The total: Their sum, and never the difference of the two ends. Computing it both ways and publishing one would let a rounding disagreement hide inside the decomposition, and the decomposition is what this page is for
The band that prices a ratio: The one with the smallest ceiling at or above it. A ratio sitting exactly on a ceiling is inside that band rather than the one above, which is what makes the distance to the next band always strictly positive
The payment: A level monthly amount that clears the loan to zero over the whole months in the term, at the band rate, convertible monthly. A rate of exactly zero gives the loan divided by the months
The bands: Yours. This page ships none, names no lender and has nowhere to put one. It therefore holds nothing that can go out of date
A table whose rates rise as the ratio falls: Not refused. It is either a table copied wrongly or a lender that genuinely prices that way, and this page has no basis for deciding which — so the step is reported as the negative number it is rather than corrected
A ratio above every band: Reported as unpriced, in words rather than as a zero. It is a statement about your table and not about the market: it does not mean nobody would lend
The unit: Unspecified, and the answer does not depend on it. Every amount is in the same unit and every ratio is invariant in it
Excluded: Fees of every kind, a fixed period that reverts, mortgage insurance, purchase taxes, and whether anybody would lend to you at all
Rounding: Display only; intermediate values remain unrounded

Correction history

A single "what the next band saves you" figure was ruled out at specification. Adding deposit lowers the rate and shrinks the loan at the same time, and the second effect is present at every deposit in the range rather than at a boundary — so one number attributing the whole saving to the band would have overstated what a boundary earns, often by several times. The model publishes three payments rather than two, and the total is defined as the sum of its two halves rather than as the difference of the ends, so a consumer cannot obtain it without them.
A deposit landing exactly on a ceiling is inside the band it reached, not the band it left. The opposite convention would have made the distance to the next band exactly zero for a reader already standing on a boundary, which reads as "you need nothing" when the truthful answer is "you have it". The comparison is inclusive, and the distance is strictly positive wherever it exists at all.