How to Calculate Car Running Costs: Fuel, Tyres & the Full Cost per Mile

Taking how to calculate car running costs as the case in point: The total cost per mile of driving is the sum of its parts — fuel, tyres, insurance, servicing and depreciation — and the tyre is usually the smallest of them, which is why it is worth getting the tyre figure right before judging it. The tyre cost per mile is price ÷ expected mileage, and the fuel cost per mile is fuel price ÷ MPG (or, in metric units, litres per 100 km ÷ 100 × price per litre). This page works both out with stated example assumptions, adds them together, and shows how the total moves with the price and the mileage in the table below. Every price and mileage here is an example used to show the working, and no tyre's real-world mileage is stated as fact, because it depends on driving, alignment, pressure and load.

On this page, how to calculate car running costs is the case in point: The worked example uses a tyre costing £130 as an example over an assumed 30,000 miles, giving 0.43 p per mile for one tyre and 1.73 p per mile for a set of four. A fuel example alongside it — using an example fuel price and an example MPG, both labelled as assumptions — gives the fuel cost per mile, and the two together are the running cost per mile before insurance, servicing and depreciation. The sections below cover the tyre maths, the fuel maths, the other costs, the table, and the mistakes that make a total cost per mile wrong.

The cost-per-mile formula for how to calculate car running costs

For how to calculate car running costs, the point is this: Cost per mile = tyre price ÷ expected mileage. For a single tyre, divide the price of one tyre by the miles it is expected to cover. For a set of four, the cost per mile is (4 × tyre price) ÷ expected mileage, which is four times the single-tyre figure. The result is usually expressed in pence or cents per mile: a tyre costing £130 over an assumed 30,000 miles gives £130 ÷ 30,000 = £0.0043, or 0.43 p per mile. The mileage in the formula is the uncertain half — it is an assumption or a measurement, never a guaranteed property of the tyre — so the worked example below states its assumptions plainly, and the section on measuring wear shows how to replace the assumption with a figure measured on the actual car.

What cost per mile means for how to calculate car running costs

Taking how to calculate car running costs as the case in point: Tyre cost per mile turns two numbers — the price and the mileage — into one number that can be compared across tyres, vehicles and budgets. The formula is cost per mile = tyre price ÷ expected mileage, and for a set of four tyres the total is (4 × price) ÷ mileage. A result of 0.5p per mile means each mile of driving wears away half a penny of tyre value, and the table below shows how that figure moves when the price or the mileage changes. The prices and mileages in this article are examples, labelled as such, because no tyre's real-world mileage can be stated as a fact: it depends on driving style, alignment, inflation pressure, load and the roads the car uses.

how to calculate car running costs: Worked example: £130 over 30,000 miles

On this page, how to calculate car running costs is the case in point: Take a tyre priced at £130 as an example, with an assumed life of 30,000 miles. The cost per mile for one tyre is £130 ÷ 30,000 = £0.0043, which is 0.43 p per mile. A set of four costs £520 and lasts the same 30,000 miles, so the cost per mile for the set is £520 ÷ 30,000 = 1.73 p per mile. Over 10,000 miles of driving, the set costs 173.33 £ in tyre wear; over 12,000 miles a year it costs 208.00 £ a year. If the same tyre lasted 40,000 miles instead of 30,000, the cost per mile for the set would fall to 1.30 p; if it lasted only 20,000 miles, it would rise to 2.60 p. Both the price and the mileage are examples, labelled as such, and the mileage is the figure that matters most because it is the one that varies most between drivers.

Cost per mile table: three prices against three mileages for how to calculate car running costs

All prices and mileages are examples used to show the working. Read across for the mileage and down for the price. That is the point this page works through for how to calculate car running costs.

Tyre price (example) 20,000 miles 30,000 miles 40,000 miles
£90 0.45 p per mile 0.30 p per mile 0.22 p per mile
£130 0.65 p per mile 0.43 p per mile 0.33 p per mile
£180 0.90 p per mile 0.60 p per mile 0.45 p per mile

Taking how to calculate car running costs as the case in point: The table shows the two directions of the formula at once: moving right along a row, the cost per mile falls as the mileage rises, and moving down a column it rises as the price rises. A £90 tyre over 20,000 miles costs 0.45 p per mile, while the same tyre over 40,000 miles costs 0.22 p — the same tyre, the same price, and a very different cost per mile, decided entirely by how long it lasts. That is why the mileage deserves more attention than the price: it is the bigger lever, and it is the one the driver can influence by the way the car is driven and maintained. Compare tyres at the same assumed mileage so the comparison is like-for-like, and use a measured wear rate where one is available.

how to calculate car running costs: Adding fuel to get the full running cost per mile

For how to calculate car running costs, the point is this: Fuel cost per mile is fuel price ÷ MPG, using an example fuel price and an example MPG, both labelled as assumptions. As an illustration, at an example price of £1.50 per litre and an example consumption of 50 MPG (UK imperial gallons), the fuel cost is about 13.6p per mile — the arithmetic is (4.546 litres per imperial gallon ÷ 50) × £1.50, which is 0.0909 litres per mile × £1.50. Add the tyre cost per mile from the worked example — 1.73 p per mile for a set of four — and the running cost before insurance, servicing and depreciation is about 15.3p per mile at those example figures. Insurance, servicing, depreciation and any finance cost are the remaining lines, and they are usually larger than the tyre line, which is why the tyre should be judged on its cost per mile rather than its price alone. Use your own fuel price and your own measured MPG for a real figure, and keep the gallon type — US or UK imperial — consistent throughout.

how to calculate car running costs: What decides how long a tyre lasts

For how to calculate car running costs, the point is this: What a tyre actually lasts depends on more than the tyre. Smooth driving, correct alignment, correct pressures and moderate loads all extend life; hard acceleration and braking, a misaligned suspension, under-inflation and heavy loads all shorten it. The road surface and the climate add their own effects, and the tyre's compound and construction set the baseline that the other factors work from. That is why this article never states a tyre's real-world mileage as a fact: the same tyre can last very different mileages on two cars, and the only mileage worth putting into the formula is one measured on the car in question — from the tread depth at fitting and at replacement, divided by the miles driven between the two.

How to measure your own tyre mileage for how to calculate car running costs

Taking how to calculate car running costs as the case in point: The way to get a real mileage figure is to measure tread wear over a known distance. Record the tread depth with a gauge when the tyres are fitted and the odometer reading at the same time. After several thousand miles, measure again: the wear rate is the depth lost divided by the miles driven, and the remaining life is the depth left above the legal minimum divided by that wear rate. The legal minimum is 1.6 mm in the UK and 2/32 inch in the USA — jurisdiction-specific figures that change, so check the current limit where the car is used. That measured wear rate is the honest input to the cost-per-mile formula, and it is far more useful than any mileage quoted for the tyre, because it reflects the actual car, the actual driving and the actual roads.

Common mistakes with cost per mile for how to calculate car running costs

Taking how to calculate car running costs as the case in point: A few errors spoil cost-per-mile comparisons. One is judging tyres by the price on the shelf instead of the price per mile — the dearer tyre that lasts longer is often the cheaper one to run. Another is taking a mileage figure from a brochure or a review and treating it as a fact about the tyre on your car, when mileage depends on driving, alignment, pressure, load and roads. A third is leaving fitting and balancing out of the price, which flatters the result. A fourth is comparing tyres at different assumed mileages, which makes the cheaper per mile figure an artefact of the assumption rather than the tyre. And the last is forgetting that the per-mile figure is for one tyre: multiply by four for the set, and remember that tyres are only one part of the cost of running a car.

how to calculate car running costs: Related pages

Frequently asked questions

How do I calculate how to calculate car running costs?

On this page, how to calculate car running costs is the case in point: Divide the tyre price by the expected mileage: cost per mile = price ÷ mileage. For a £130 example tyre over an assumed 30,000 miles, that is 0.43 p per mile for one tyre, or 1.73 p per mile for a set of four. The tyre cost per mile calculator runs the same formula with your own figures.

What is a good tyre cost per mile?

There is no single good figure, because it depends on the price and the mileage together. At the example figures on this page, a £130 tyre over 30,000 miles costs 0.43 p per mile for one tyre. Compare tyres at the same assumed mileage and judge the result against your own budget — and remember that the mileage is the figure that moves the answer most. That is the point this page works through for how to calculate car running costs.

Does the price include fitting?

On this page, how to calculate car running costs is the case in point: It should, if fitting, balancing and any disposal charge were part of what was paid. Leaving them out understates the true cost per mile, so add them to the price before dividing by the mileage. The worked example above uses the tyre price alone as an illustration, so add the fitting cost for a real figure.

How can I make my tyres last longer?

For how to calculate car running costs, the point is this: Keep pressures at the placard figure, checked cold; have the alignment checked when the tyres show uneven wear; drive smoothly instead of accelerating hard and braking late; avoid overloading the car; and rotate the tyres if the manufacturer recommends it. Each of these extends the mileage in the formula, which cuts the cost per mile directly.

What is the legal minimum tread depth?

On this page, how to calculate car running costs is the case in point: In the UK the legal minimum tread depth is 1.6 mm across the central three-quarters of the tread, and in the USA it is 2/32 inch. Both are jurisdiction-specific limits and they change, so check the current figure where the car is used. Most drivers replace tyres before the legal minimum, because wet grip falls off well before the tread is bare.