How to Compare the Full Cost of a UK Commute

Business & Money Desk 2026-10-11 08:19 5 min read

Iconic red double-decker bus navigating a roundabout in a busy UK city center.

A cheaper petrol or diesel price does not always make your commute cheaper overall. To estimate what you will spend, use your own weekly mileage and your vehicle’s real-world fuel economy, then add parking, tolls and any costs for public transport or park-and-ride. Check local pump prices on the day you plan to fill up, because prices vary by place and date.

Calculate weekly fuel use from your mileage

Start with the miles you actually drive in a typical week. Include the return journey and any regular detours, such as a school run or a trip to a station. If your route changes from week to week, work out a representative average from your recent journeys.

Use this formula when fuel economy is shown in miles per UK gallon (mpg):

Weekly fuel cost = weekly miles ÷ miles per gallon × 4.546 × price per litre

There are about 4.546 litres in a UK gallon. The result estimates the cost of fuel used for those miles; it does not include parking, tolls, vehicle wear or the cost of owning and insuring a car.

Use the mpg figure that best reflects your driving. A manufacturer’s official figure can differ from real-world results, especially in stop-start traffic, cold weather or on short journeys. If you track fuel purchases and mileage, your own average can give a more useful estimate.

For a diesel vehicle, use its diesel economy and the diesel price per litre. For a petrol vehicle, use its petrol figures. Do not compare the two fuel types using one price or efficiency figure.

How to Compare the Full Cost of a UK Commute

Worked example: estimate a week of petrol commuting

Assumptions: 150 miles of commuting in a week; a petrol car averaging 40 mpg; petrol priced at £1.50 per litre on the day checked. These figures are for illustration only, not current UK prices.

Divide 150 weekly miles by 40 mpg: 3.75 UK gallons.
Convert gallons to litres: 3.75 × 4.546 = about 17.05 litres.
Multiply by the assumed price: 17.05 × £1.50 = about £25.58 in weekly fuel.

If the same car’s real-world economy were 35 mpg, the estimate would rise to about 19.48 litres, or £29.22 at the same assumed price. That difference shows why your own mileage and fuel economy matter as much as the number on a forecourt sign.

To estimate a monthly amount, multiply the weekly figure by the number of commuting weeks in your month. Four weeks is a quick approximation; using your actual workdays gives a closer budget, especially around holidays or variable shifts.

Add parking, tolls and other journey costs

Fuel is only one part of the commute. Add costs that apply to your route and schedule, such as:

Daily or monthly parking, including a workplace permit or station car park.
Tolls and any applicable road or congestion charges.
Regular bus or train fares, or a park-and-ride ticket.
A practical allowance for occasional extra trips, if they are part of your normal commute.

Keep regular commuting costs separate from broader car costs such as insurance, tax, servicing and depreciation. Include those ownership costs if you are deciding whether to keep a car or switch modes; avoid counting them as a new cost of one particular trip if you would pay them either way.

A lower-priced filling station may also involve a detour. If you drive extra miles to reach it, include those miles in your calculation. Compare the saving on the fuel you buy with the fuel used and time spent on the extra trip.

Compare the whole journey with public transport

Compare options for the same origin, destination and number of travel days. A weekly car estimate can be set beside the weekly cost of a bus or train ticket, or a mixed journey such as driving to a station and taking the train for the rest of the route.

Check whether fares, parking and travel times change by day or time. If someone else shares the car, divide shared journey costs among the people travelling when that reflects how you split the expense. Keep each option’s assumptions visible so you can see what would change the result, such as a fare increase, a change in office days or a different parking arrangement.

The cheapest option on paper may not work for every schedule. Consider the time required, service frequency and how reliably you can make connections alongside the weekly cost.

Find current UK petrol and diesel prices

The Department for Energy Security and Net Zero publishes a collection of monthly UK road fuel price statistics. These figures provide national context; they are not a live quote for a particular forecourt. The collection is updated monthly, so check its publication date and the period covered when using it.

For a local comparison, check a price listing that shows when a forecourt’s price was reported, and verify the price at the station before making a special trip. Record the price per litre and date you checked it, then use that figure in your calculation. Petrol and diesel prices can differ between nearby stations and can change after a listing is updated.

Recalculate when your regular route, weekly mileage, vehicle or fuel price changes. That keeps the comparison tied to the commute you make now rather than to an old estimate.

Source: UK Department for Energy Security and Net Zero

Context & actions About this article

Source check How the estimate works

The fuel estimate uses weekly mileage, miles per UK gallon and a dated price per litre; example prices are assumptions, not live quotes.

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