HOW MUCH CAN I BORROW?
...is the wrong question if the income number isn’t stable yet.
Most mortgage affordability calculators turn income into a single borrowing number.
That works if the income is simple.
It breaks badly when the case includes bonus, commission, overtime, allowances, second-job income, or anything that gives lenders room to interpret the same borrower differently.
This calculator shows where your borrowing number may stretch, compress, or split once your actual income pattern enters the equation.
Earning Self-Employed income including dividends, retained profit or day-rate contracts? Use our self-employed borrowing range calculator instead.
Before you run it
What to Know Before Using This Calculator
The same payslip total can produce very different borrowing results once a lender starts separating clean income from income that needs proving.
- A steady monthly bonus behaves differently from one annual payout
- Commission depends on the window being measured, not just the total earned
- Overtime can look normal in your job and still look temporary in affordability
- Guaranteed income and variable income do not carry the same weight
- A wider gap between the ranges means lender choice matters more
Step 1 of 1
How much can I borrow?
Estimate your mortgage borrowing range using salary, bonus, commission, overtime, commitments and mortgage term.
What This Calculator Shows That Most Don’t
- Why the same employed income can produce different borrowing ranges between lenders
- How bonus, commission and overtime can lift the result, then get cut back by evidence, timing or trend
- Where allowances, second jobs and variable pay stop behaving like simple salary
- How much the result can move when income is accepted, averaged, capped or ignored
- Whether the higher end of the range needs a stronger lender route before you rely on it
Before you spend months building plans around a mortgage, understand where people usually get caught out.
Most people only realise how differently mortgage applications are interpreted once something slows down, falls apart, or stops making sense. This short walkthrough helps you recognise problems earlier, before you commit too much time, money or certainty to the wrong path.
See where borrowers get caught out →Why Mortgage Borrowing Doesn’t Start With Your Total Income
Most borrowers start with the number they earn.
Lenders want a number they can evidence, reapeat and defend over the life of the mortgage.
That gap can be small when the income is a smooth basic salary.
It gets wider when the income depends on patterns: bonus cycles, commission rhythm, overtime history, allowances, second-job income, or anything that needs proving before it counts.
That’s where a normal borrowing calculator can start to mislead.
It gives a number before the lender has finished deciding which parts of the income actually belong in the calculation.
Why Variable Income Changes the Borrowing Result
Variable income turns a mortgage affordability calculation into a timing problem.
The lender has to choose which version of the income is most likely to continue.
Last month.
Last three months.
Last year.
Latest bonus.
Average bonus.
Lowest recent figure.
That choice can reshape the borrowing result before the rest of the case is even touched.
That’s why bonus, commission, overtime and other enhancements need to be looked at separately.
Bonus income
Bonus income creates a strange affordability problem because the lender isn’t only looking at the amount paid.
It’s looking at the cycle behind it.
A large annual bonus can strengthen the case with one lender and get averaged, capped, reduced or pushed aside by another. The difference often comes down to history, wording, timing, and whether the bonus looks like part of normal pay or a one-off performance spike.
» MORE: Bonus Income Mortgages: Why High Flyers Get Clipped
Commission income
Commission usually lives closer to the application date.
That makes the measurement window more important.
A lender may look at the latest three months, six months, twelve months, or the lowest recent figure. So one weaker month can drag down a case that still looks strong across the year
Overtime income
Overtime gets judged on whether the pattern looks sustainable.
Some roles make heavy overtime normal. NHS, care, emergency services, shift work and frontline roles can all produce payslips that look messy but still follow a pattern lenders understand.
The problem starts when the lender sees the extra income as temporary pressure rather than normal earnings.
» MORE: Overtime Mortgages: When Payslips Look Like Shopping Receipts
Other allowances and enhancements
Not every payslip line fits neatly into bonus, commission or overtime.
Some borrowers have shift premiums, location allowances, car allowances, call-out payments, standby payments, bank work, unsocial hours, retainers, or employer-specific enhancements with names that only make sense inside that workplace.
Those payments can help affordability, but the label alone doesn’t decide the outcome.
The lender still has to work out whether the income is contracted, regular, evidenced, role-based, likely to continue, or too unusual to rely on fully.
The less familiar the income looks, the more the result depends on whether the lender understands the pattern behind it. The overtime mortgages article will get you closest to the answer.
Why the Same Income Can Produce Different Borrowing Results
When you step back, what a lender has to do here is pretty wild.
It’s trying to turn a payslip into a 25-year assumption.
Take an annual bonus.
The lender has to decide whether that bonus is just part of how this person gets paid, or whether this year lined up nicely.
Who do they work for?
What does that industry look like?
Is the bonus normal for the role?
What happens if they change job?
What happens if the market slows?
What happens if life changes and they can’t keep performing at the same level?
Nobody can answer all of that perfectly.
So lenders choose what they want to understand.
One lender builds its process around a certain kind of income. It knows the sector, the pay structure, the evidence, the normal range, and what a strong case looks like.
That lender can use more of the income because it knows what it’s looking at.
Another lender takes the 80/20 efficiency route.
It doesn’t ignore the income, but it doesn’t fully trust it either. So it averages it, caps it, reduces it, or drags the case back to a safer number.
Then there are lenders that specialise in a different part of the market altogether.
They can be excellent for one type of borrower and awkward for another. Strong on annual bonuses, weak on monthly commission. Comfortable with NHS enhancements, cautious with employer-specific allowances. Good with overtime, poor with second-job income.
That’s the trade-off.
The more complicated the income mix becomes, the less likely it is that one lender uses every part of it perfectly.
The aim is to find the lender that wastes the least income while still fitting the rest of the case.
LENDER FIT RANGE
Same income. Different lender outcome.
What The Calculator’s Lender Fit Range Shows You
This is why the calculator doesn’t stop at one number.
The standard estimate gives you the normal planning figure.
The lender-fit range shows what happens when the income finds a better route through the market.
If the range stays tight, lender choice isn’t doing as much heavy lifting.
If the range opens up, the result will vary massively from one lender to the next.
The top end can be achievable, but it has to be placed properly.
That’s the point of the range.
It shows whether the borrowing figure is straightforward, or whether the income needs a more careful route.
How To Read Your Calculator Result
Start with the mortgage size you need.
That’s the target.
If the standard estimate gets you there, move on to mortgage readiness.
If you need the higher end, work backwards.
Which income has to carry the gap: bonus, commission, overtime, allowances, second job or other income?
That tells you where the case needs the most pressure-testing before you treat the number as usable.
It reveals which lenders were realistic in the first place.
Borrowing Power Can Become a Trap
Affordability figures are the high-dopamine part of mortgages.
One number can make the next move feel real fast.
You start looking at properties differently. You stretch the search. You treat the higher figure like it’s already been tested in the real market.
That’s where the trap sits.
A borrowing figure is only one marker on the map.
It won’t tell you whether the wider case is ready for the property, lender, timing and evidence behind the move.
Before you build the next step around the number, run the Mortgage Readiness Check.
See How Lenders Are Likely to Read Your Case
Most borrowers compare rates before they know whether a lender will actually like their case.
That’s how people waste time with the wrong bank, get weaker offers, or end up with avoidable declines.
The readiness check gives you an early read on how your case is likely to land, where the pressure points are, and whether lender choice needs more care.
- Avoid wrong lenders
- Spot pressure points
- Understand case fit
- Check before applying
See How Lenders Are Likely to Read Your Case
Mortgage Readiness Check
See how lenders will read your case.
Whether the income pattern looks stable enough to rely on, and how much of it they are prepared to include.
Employed Mortgage Affordability Calculator FAQs
Is this a mortgage affordability calculator or a borrowing calculator?
Both phrases are asking the same thing: how much can I borrow?
“Mortgage affordability calculator” is the lender-style phrase. “Mortgage borrowing calculator” is the borrower-style phrase.
This page uses both because the result has to do both jobs: estimate the borrowing number and show where lender fit can change it.
Is a borrowing range better than one “how much can I borrow?” figure?
A single figure is easier to read.
A range helps more when the income needs interpretation.
If all the income behaves like basic salary, one number may be enough. If the case includes bonus, commission, overtime, allowances or other variable pay, the range shows how much the answer depends on lender fit.
Is this the same as an agreement in principle?
No.
An agreement in principle comes from a specific lender. It can involve a credit check, lender criteria and the details entered at that point.
This calculator helps you understand the borrowing range before that stage, especially where the income could be read in more than one way.
Should I use the standard estimate or the top of the range when looking at properties?
Use the standard estimate as the safer planning number.
Use the top of the range when you know what has to go right for that number to work.
That usually means knowing which income needs to count, how strong the evidence looks, and whether the case needs a lender that fits that income properly.
What if part of my income isn’t employed income?
Use the calculator for the employed part of the case.
If the borrowing figure depends on business accounts, retained profit, company dividends, a contractor day rate or income that sits outside payroll, the case may need a different route.
That’s where the self-employed mortgage calculator or contractor guidance gives a better read.
