What this calculator works out
Enter when a car was first registered and what the odometer reads now, and this gives its average mileage per month and per year, along with how that compares to a typical UK car.
It is useful when judging a used car, checking whether you are on course to exceed a lease or PCP mileage allowance, or working out a realistic figure to declare to an insurer.
The month of registration matters more than people expect. Knowing only the year leaves the car's age uncertain by up to twelve months, which on a three-year-old car shifts the annual average by a third. The number plate usually tells you the month, and this page explains how to read it.
Enter your details
Before you calculate
- Use the date of first registration from the V5C log book, not the model year. A car built in late 2020 may not have been registered until 2021.
- The month matters. "A 2021 car" could mean January or December 2021, and on a car of that age the difference moves the annual figure by well over a thousand miles.
- If the mileage came from an old MOT certificate rather than the car in front of you, change the reading date to match. Otherwise the average comes out too low.
On a UK plate registered since 2001, the two digits after the first two letters are the age identifier. Between March and August it is the year: 25 means March to August 2025. Between September and February it is the year plus fifty: 75 means September 2025 to February 2026. So a 71-plate car was registered between September 2021 and February 2022, which is enough to date it within six months without the log book.
How this calculator works
Age in months = (reading year − registration year) × 12
+ (reading month − registration month)
Miles per month = mileage ÷ age in months
Miles per year = miles per month × 12The arithmetic is division. The care goes into the age, because that is where the error creeps in.
Counting whole months between two dates is more reliable than dividing days by 30.44, and it matches how registration dates are recorded. Where you do not know the month, the calculator assumes July, the middle of the year, which keeps the error to about six months either way rather than up to twelve.
The result is an average across the whole life of the car. It is not a prediction of what the car does now, and it says nothing about how the miles were distributed. A car with a 9,000-mile average might have covered 20,000 in its first year as a company car and 4,000 a year since.
Worked example: a 71-plate car
A car first registered in September 2021, reading 46,500 miles on 28 July 2026:
- Age: September 2021 to July 2026 is 4 years and 10 months, or 58 months
- Miles per month: 46,500 ÷ 58 = 802 miles
- Miles per year: 802 × 12 = 9,621 miles
- Against a 7,100-mile benchmark, that is 36% above average
Now suppose you only knew it was "a 2021 car". Assuming January gives 8,455 miles a year; assuming December gives 10,145. The same odometer reading produces answers nearly two thousand miles apart, purely from not knowing the month. That is why the plate is worth reading.
Understanding the result
The annual figure is the one to compare, because that is the unit insurers, lease agreements and used car adverts all use.
| Miles a year | Miles a month | How it reads |
|---|---|---|
| Under 5,000 | Under 420 | Low. Attractive on paper, but check for short-journey wear |
| 5,000 to 9,000 | 420 to 750 | Around average for a UK car |
| 9,000 to 15,000 | 750 to 1,250 | High. Commuting or business use |
| Over 15,000 | Over 1,250 | Very high. Expect motorway miles and a fuller service record |
Low mileage is not automatically good. A car that has covered 2,000 miles a year on short trips from cold may have a tired battery, corroded brakes, perished rubber and, on a diesel, a clogged particulate filter. A 12,000-mile-a-year car with a full service history and mostly motorway use can be in better mechanical order.
Diesel cars average noticeably more than petrol ones — roughly 8,300 miles a year against 6,200 in recent survey data — so judge a diesel against a diesel.
UK plate age identifiers
| First registered | Identifier |
|---|---|
| March to August 2022 | 22 |
| September 2022 to February 2023 | 72 |
| March to August 2023 | 23 |
| September 2023 to February 2024 | 73 |
| March to August 2024 | 24 |
| September 2024 to February 2025 | 74 |
| March to August 2025 | 25 |
| September 2025 to February 2026 | 75 |
| March to August 2026 | 26 |
A private or personalised plate breaks this, because it can be transferred to a car of any age — though never to make a car look newer than it is. If a plate does not follow the pattern, check the V5C.
Things that affect the result
- Registration date against build date. Pre-registered and unsold stock can be several months older than the plate suggests.
- Imports. A vehicle first registered abroad and later registered in the UK will have a UK date later than its true age.
- How the miles were spread. An average tells you nothing about the pattern, and the pattern is what wears a car out.
- Replaced instrument clusters. A replacement unit can reset or alter the displayed reading. It should be documented.
- Odometer tampering. Reducing a reading to raise the price is fraud, and it is not rare. MOT history is the check.
- Kilometres. An imported car may read in kilometres. Divide by 1.609 to get miles.
Common mistakes
- Using the model year. A "2022 model" may have been registered in 2021 or 2023.
- Ignoring the month. The single largest source of error on a car under five years old.
- Using an old MOT reading against today's date. Set the reading date to match the reading.
- Treating the average as current use. Insurers want your expected mileage for the year ahead, not the car's lifetime average.
- Assuming low mileage means good condition. Service history and use pattern matter more.
- Comparing across fuel types. Diesels average a third more than petrol cars.
Frequently asked questions
What is a good mileage for a used car?
Around 7,000 to 8,000 miles a year is typical for a UK car, so a five-year-old car with 35,000 to 40,000 miles is unremarkable. But mileage on its own decides very little. A higher-mileage car with a full service history and steady motorway use is often a better buy than a low-mileage one that has done nothing but short cold trips. Judge the two together.
How do I check a car's real mileage history?
Use the free MOT history service on GOV.UK. It lists the odometer reading recorded at every MOT, which shows you the actual year-by-year pattern rather than a lifetime average, and reveals any reading that has gone down or jumped implausibly. It needs only the registration number. For a car over three years old it is the single most useful free check available.
Is it illegal to wind back a car's odometer?
Adjusting an odometer is not in itself an offence, but selling a vehicle without disclosing that the reading is incorrect is, under consumer protection law, and it is treated as fraud. It remains common enough to be worth checking. Compare the reading against MOT history, and against wear on the pedals, steering wheel and driver's seat.
Why does the month of registration matter so much?
Because it can change the age by up to twelve months. On a three-year-old car that is a third of its life, which moves the annual average by a third. Knowing only the year is usually enough for a rough sense of things and not enough for an insurance declaration or a lease calculation.
How do I work out the registration month from the plate?
On plates issued since September 2001, the two digits after the first two letters give it. March to August uses the year itself, so 25 is March to August 2025. September to February uses the year plus fifty, so 75 is September 2025 to February 2026. This narrows it to a six-month window. A personalised plate can be transferred between cars, so check the V5C if the plate looks inconsistent.
Will this tell me if I am going to exceed my lease mileage limit?
It gives you the average that matters for that question. Compare the annual figure against your agreement's yearly allowance, and remember that excess mileage is charged per mile at a rate set in the contract. If your average is running above the allowance, it is usually cheaper to renegotiate the allowance than to pay the excess at the end.
What mileage should I declare to my insurer?
Your best honest estimate of what you expect to drive in the year ahead, not the car's lifetime average. If your driving has changed — a new job, retirement, working from home — the historic figure will mislead. Under-declaring to reduce a premium can give the insurer grounds to reduce or refuse a claim, so a realistic figure is worth more than a flattering one.
The car reads in kilometres. What do I do?
Divide the reading by 1.609 to convert to miles before entering it, or enter the kilometre figure and read the results as kilometres per month and per year. Just do not compare a kilometre figure against the mileage benchmark.
Is what I enter stored?
No. Figures are processed in your browser and never transmitted or retained.
Related tools
References
These organisations publish the guidance and figures behind this page.
- GOV.UK — check the MOT history of a vehicle — free odometer readings recorded at every MOT, which show the real year-by-year pattern
- Department for Transport — National Travel Survey — the source of UK average annual car mileage figures, including the split between petrol and diesel
- GOV.UK — vehicle registration — V5C log books, first registration dates and number plate rules
Average mileage figures are revised as new survey data is published. Check the source for the current position before relying on the benchmark.