How to Calculate Your Real Weekly Commuting Cost

The cheapest commute is not always the one with the lowest fuel price. To compare petrol, diesel, an electric vehicle or public transport fairly, calculate the cost of the complete weekly journey: energy, distance, parking, charging access and fares. Local prices and route conditions can change the result, so use figures checked for your own area and travel days.

Start with the cost of the whole journey

For a petrol or diesel car, use this formula:

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

First multiply the one-way distance by the number of return trips. Then use your vehicle’s real-world fuel economy if you know it. The figure printed in a brochure may not match stop-start traffic, winter driving, heavy loads or motorway speeds.

Add costs that are easy to overlook:

• Daily or weekly parking
• Congestion, clean-air or toll charges
• A paid station or workplace parking permit
• Occasional longer routes caused by traffic
• Maintenance and depreciation, if you are comparing the full cost of owning a car

For a diesel vehicle, use its actual miles-per-gallon figure and the local diesel price. Do not assume diesel is cheaper simply because the car uses less fuel; the pump price and vehicle efficiency both matter.

A worked example using hypothetical figures

Imagine a commuter travelling 18 miles each way, five days a week. The weekly distance is 180 miles. These figures are illustrative, not a UK average.

The petrol example assumes 42 mpg and petrol at £1.50 per litre. The calculation is 180 ÷ 42 × 4.546 × £1.50, giving about £29.24.

The electric-car example assumes efficiency of 3.5 miles per kWh and home charging at 30p per kWh. The calculation is 180 ÷ 3.5 × £0.30, or about £15.43. Public charging may cost more, while a cheaper tariff could reduce home-charging costs.

The bus figure is a hypothetical weekly ticket price. Check the actual fare, ticket zone, peak-time restrictions and whether a season ticket offers better value. The table shows how the method works; it does not prove that one option is cheapest everywhere.

Check local prices before comparing options

Use a current price from a nearby forecourt, rather than an unverified national average. Record the price per litre and the date checked. For an electric vehicle, check the tariff for the charger you would actually use, including connection fees, parking charges and idle fees.

For public transport, check the operator’s own fare page or a journey planner for the exact origin, destination and travel times. Rail, bus and tram prices can differ by zone, time of day, ticket type and booking date. A route that looks cheaper may take longer or require an additional connection.

Repeat the comparison for your real working pattern. A three-day office week, occasional parking, remote work or a lift-sharing arrangement can change the answer more than a small movement in the pump price.

Why the result can change from week to week

Driving style, vehicle type and route all affect consumption. Cold starts, congestion, hills, tyre pressure, roof boxes and acceleration can reduce fuel economy. An electric car’s range and energy use can also change with temperature, speed, heating and charging losses.

The most useful comparison is therefore a range, not a single precise number. Test a low-cost and high-cost scenario using different fuel prices, traffic conditions or parking days. Include the time taken and reliability as separate considerations, because the lowest cash cost may not be the most practical commute.

Before making a decision, check the local forecourt price, the charger tariff, the public-transport fare and the route-specific parking cost on the same day. That gives you a current comparison without treating a national average as your personal bill.

Source: GOV.UK