Car affordability calculator
No UK body publishes a percentage of your income that you should spend on a car, so this calculator works the other way round: it adds up what a particular car costs to run over a year — vehicle tax, fuel or charging, the MOT fee, insurance and servicing — and gives you the monthly figure to hold against your own budget.
There is no UK rule about what share of your income a car should take.
MoneyHelper, run by the statutory Money and Pensions Service, publishes a running-cost checklist and no ratio at all. The Financial Conduct Authority stated in PS18/19 (paragraph 2.24) that it did not intend to prescribe the use of debt-to-income or repayment-to-income ratios, and its CONC 5.2A creditworthiness rules contain no numeric threshold. The "20% of income" and "20-4-10" rules you will find on other calculators come from United States personal-finance writing. They have no UK authority behind them, so this page does not use one.
What can be sourced is the cost side, and that is what this tool builds. Every line below says where its number came from.
The car
Vehicle tax is UK-wide, but MOT testing is not: the fee and the age of the first test both differ in Northern Ireland, and the Ofgem price cap covers Great Britain only.
This decides which of the three vehicle tax regimes applies, and whether the car needs an MOT yet.
On the V5C logbook. For a car registered from April 2017 it only affects the first-year rate, which the original buyer already paid.
Only used to work out the £440 Expensive Car Supplement, which runs in years 2 to 6. It is assessed on the price the car listed at when new — over £40,000 for petrol, diesel and alternative fuel, and £50,000 for zero emission cars first registered on or after 1 April 2025. A used listing does not show that price, so leave this blank unless you know it. Never infer it from the asking price.
How far you drive
Seeded with the DfT National Travel Survey figure for petrol cars in England in 2024: 6,200 miles, against 7,100 for cars overall. Survey respondents estimate their own mileage rather than reading it off an odometer, so treat it as a starting point. Mileage moves the fuel line more than anything else on this page.
All cars
7,100
petrol
6,200
diesel
8,300
hybrid
8,000
electric
8,900
Fuel
Starting value, not a source. No UK body publishes an average real-world MPG, so this is an assumption until you replace it with the figure your own car actually returns.
161.61p a litre
UK average pump price, week commencing 31 August 2026 (DESNZ)
Pump prices move every week, so the fuel line is shown as a band of plus or minus 6% around the current UK average. Hybrids are costed on petrol, because that is what they burn. Uses imperial gallons of 4.54609 litres, as UK MPG figures do.
Insurance and servicing
ABI average premium paid, Q2 2026.
ONS household average, FYE 2025.
Why the insurance default is nearly useless on its own. £566 is the average premium actually paid on comprehensive privately owned car policies in Q2 2026, published by the Association of British Insurers on 29 July 2026. It was £560 the quarter before and peaked at £635 in Q1 2024. It averages across every age, postcode and car. FCA data for England and Wales puts the average paid by 17 to 24 year olds at £1019, and reports an area spread from £356 in Ipswich to £767 in West London. Those area figures are regression coefficients with controls applied, not observed prices. Put your own renewal number in the box.
Why there is no authoritative servicing figure. The ONS publishes a vehicle maintenance and repair price index (series D7IP), which measures how fast the cost is changing — 6.5% in the year to July 2026 — but not what the cost is. The only level figure from a UK statistical source is ONS Family Spending: £9.50 a week on repairs and servicing in FYE 2025, which is £494 a year. That is an average across all households, including the many that spent nothing, so it is a household mean rather than what a car owner spends. It is the default here only because it is sourced. Your own service quote is better.
The MOT fee, and what it does not cover
Great Britain, class 4 car
£54.85
DVSA maximum. First test on the third anniversary of registration.
GOV.UKNorthern Ireland, full test
£38.00
DVA. Retest £29.50. First test at four years old, not three.
nidirectBoth are maximum fees rather than fixed prices, carry no VAT, and have not changed since 2010. The fee buys the test and nothing else: DVSA recorded a 28.08% initial failure rate across cars and vans in Great Britain in 2024/25, with 2.44 defects on average behind each failure, and 7.7% of all tests turned up at least one dangerous defect. DVSA does not test in Northern Ireland, so these figures do not describe DVA testing. Repair cost after a failure is not in the fee and not in the total below. It sits inside whatever you put in the servicing and repairs box.
A minor defect still passes, with the defect recorded on the certificate. Only major and dangerous defects fail a car.
DVSA MOT testing dataRunning cost, a month
£2,327 a year · 37.5p a mile at 6,200 miles
This is not yet a figure for your car. The insurance and servicing lines are still a published population average, and almost nobody is the average. Replace them with your own number and the total means something.
Registered on or after 1 April 2017. 2026/27 rates from GOV.UK.
626 litres a year. Pump price sourced; the MPG is a starting value, not a source.
DVSA maximum fee, Great Britain. Repairs are not included.
ABI average premium paid, Q2 2026 — an average across all drivers, not a quote for you.
ONS Family Spending FYE 2025 household average of £9.50 a week, across all households including those that spent nothing.
Fuel at today's price band: £952 to £1,073 a year.
Vehicle tax is calculated at 2026/27 rates. Cars registered from April 2017 pay a one-off first-year rate based on CO2, then a flat standard rate every year after. As a used buyer you pay the standard rate — the first-year rate was settled by the original buyer. GOV.UK rate tables.
Depreciation is not in this total
It is usually the largest single cost of owning a car, and it is missing here because no UK public body publishes used-car depreciation. Any calculator that hands you a depreciation figure has estimated it, from private trade valuation data or from an assumption of its own. We would rather tell you the number is absent than invent one.
Also excluded
- Finance interest, if the car is bought on credit
- Tyres, and any repair beyond the servicing figure you entered
- Breakdown cover
- Parking, permits and tolls
- Clean air zone and congestion charges — check a car against the zones
- The cost of taxing the car on the day you buy it: vehicle tax is cancelled when a car is sold and refunded to the seller, so the buyer must tax it before driving or declare SORN
Why this page refuses to give you a percentage
Search for a car affordability rule and you will be told to spend no more than 20% of your take-home pay on motoring, or to follow "20-4-10": 20% down, a four-year term, and total transport costs under 10% of gross income. Both come from United States personal-finance writing. Neither has a UK source. MoneyHelper, which is run by the statutory Money and Pensions Service and is the closest thing the UK has to an official consumer money guide, gives a checklist of running costs and names no ratio. The Financial Conduct Authority went further and said in PS18/19, at paragraph 2.24, that it did not intend to prescribe the use of debt-to-income or repayment-to-income ratios; its CONC 5.2A creditworthiness rules set no numeric threshold either.
That leaves a choice: repeat a number with nothing behind it, or price the car. This page prices the car. The monthly total above is a cost, not a verdict. The comparison with your income is one only you can make, because it depends on everything else you are already committed to.
Where each figure comes from
| Line | Source | What it is |
|---|---|---|
| Vehicle tax | GOV.UK rate tables, 2026/27 | A statutory rate. Exact, once the registration date and CO2 are right. |
| Fuel price | DESNZ weekly road fuel prices | The published UK average for the week. Your local pump will differ. |
| Electricity price | Ofgem default tariff cap, Great Britain | A regulated maximum unit rate for a Direct Debit customer, not a price everyone pays. Northern Ireland is regulated separately. |
| MPG or miles per kWh | Yours, or an assumption | No UK body publishes a real-world MPG average. The electric default is the DfT modelling assumption, not a measurement of your car. |
| MOT fee | DVSA and DVA maximum fees | A capped fee, VAT-free, unchanged since 2010. Repairs are separate. |
| Insurance | ABI premium tracker, Q2 2026 | An average of prices paid across all drivers. Almost nobody is the average. |
| Servicing and repairs | ONS Family Spending, FYE 2025 | A weekly average across all households, including those that spent nothing. |
| Depreciation | No UK public source exists | Excluded. Normally the biggest cost of all. |
What UK households actually spend on transport
ONS Family Spending for FYE 2025 puts average weekly household expenditure at £676.60, of which £96.40 is transport — 14.2% of the total. Inside that: £18.40 a week on petrol, diesel and motor oils, £14.30 on vehicle insurance, £9.50 on repairs and servicing and £4.00 on vehicle tax.
Read that carefully before using it as a benchmark. Every one of those numbers is an average across all households, including households with no car, so they are lower than what an actual car owner spends and they are not a target for anyone. They describe the country, not you. That is a statement about what households spend, not a rule about what you should spend. The ONS publishes no such rule.
ONS Family SpendingGreat Britain and Northern Ireland are not the same
Vehicle tax is a UK-wide DVLA matter and works identically in both. Three of the inputs on this page do not. MOT testing in Great Britain is run by DVSA at a maximum class 4 fee of £54.85, with the first test due on the third anniversary of registration; in Northern Ireland it is run by DVA at £38.00, retest £29.50, and the first test is not due until the car is four years old. The Ofgem price cap covers England, Scotland and Wales only, so an electric car kept in Northern Ireland should be costed on the Power NI tariff approved by the Utility Regulator (UREGNI). And Northern Ireland has no ultra low emission zone, clean air zone or low emission zone at all, so none of those charges can apply there.
Ofgem price cap unit ratesIf the car is being bought on finance
The monthly payment sits on top of everything on this page. It is a separate cost from running the car, and this calculator does not include it. Three points of fact. A personal contract purchase is legally a form of hire purchase, so you do not own the car until the final payment and any option-to-purchase fee have been paid. Under section 99 of the Consumer Credit Act 1974 you may end the agreement at any time before the final payment falls due. And section 100(1) sets the sum payable on that termination as the amount by which one half of the total price exceeds the sums paid and due — with section 189(1) making "total price" include any sum payable on exercising the option to purchase, so the balloon payment sits inside that half.
The half-rule figure is not a ceiling on what you can be asked for, and it is routinely reported as though it were. Section 99(2) says termination does not affect liabilities that have already accrued, so arrears remain owed. The Financial Ombudsman Service has decided (DRN-3597504) that excess mileage may be charged in addition to the half-rule sum. And section 100(4) allows the amount to be increased where the car has not been taken reasonable care of.
This page states those rules and nothing more. It does not recommend a lender, a product or a course of action.
For guidance only, and factual information rather than advice. Vehicle tax at 2026/27 rates; pump prices from the DESNZ weekly series; electricity from the Ofgem cap for Great Britain; MOT fees from DVSA and DVA; insurance from the ABI Motor Insurance Premium Tracker Q2 2026; servicing from ONS Family Spending FYE 2025; mileage from the DfT National Travel Survey 2024. Figures verified 9 September 2026. Depreciation is excluded because no UK public body publishes it.