Journey Times: Common Mistakes, Tips and FAQs
Introduction
UK drivers juggle imperial gallons, pence per litre and pence per kWh. Converting everything to the same basis is the key to fair comparisons.
This article covers the most common mistakes people make with journey Times, what really moves the result, and answers to the questions we hear most often.
Why it matters
Accurate motoring numbers help you budget journeys, claim mileage relief from HMRC and decide whether an electric car makes financial sense for you.
How it's calculated
Time = distance ÷ average speed. We add your planned stop time on top.
What changes the result most
The result depends on the choices you make in the calculator, so it's worth trying several combinations. In a typical example, journey time is 2h 39m.
Common mistakes to avoid
- Using US MPG figures for UK calculations.
- Ignoring depreciation and insurance in cost-per-mile estimates.
- Forgetting to claim mileage allowance relief when your employer pays below HMRC rates.
- Comparing EVs using public charging prices when you'll mostly charge at home.
A quick example
With the inputs below, journey time comes out at 2h 39m.
| Input | Value |
|---|---|
| Distance | 120 miles |
| Average speed | 50 mph |
| Stops | 15 minutes |
Tips
- UK MPG uses imperial gallons (4.546 litres), which differ from US gallons.
- HMRC's approved mileage rate is 45p per mile for the first 10,000 business miles.
- Home EV charging on an off-peak tariff is usually far cheaper than public rapid chargers.
- Depreciation is often the largest hidden cost of owning a newer car.
Frequently asked questions
What's the quickest way to work out journey Times?
Use our free journey Time Calculator. It applies this method automatically: Time = distance ÷ average speed. We add your planned stop time on top.
What MPG should I use?
Use your real-world figure from your car's trip computer if you can; official figures are often optimistic.
Can I claim for commuting miles?
No. Normal commuting to a permanent workplace doesn't count as business mileage.
How often do HMRC mileage rates change?
Rarely. The 45p rate has been unchanged for many years, but always check GOV.UK.
Related calculators
- Fuel Cost Calculator
- MPG Converter
- Car Cost Per Mile Calculator
- EV Charging Cost Calculator
- EV vs Petrol Cost Calculator
- Car Depreciation Calculator
Try the journey Time Calculator
Enter your own figures and get an instant answer – free, no sign-up.
Open the journey Time CalculatorFor the full method, read How to Calculate Journey Times in the UK: Step-by-Step Guide.
More motoring guides
- Fuel Costs for a Journey: Common Mistakes, Tips and FAQs
- MPG Conversions: Common Mistakes, Tips and FAQs
- Car Running Cost Per Mile: Common Mistakes, Tips and FAQs
- EV Charging Costs: Common Mistakes, Tips and FAQs
- EV vs Petrol Running Costs: Common Mistakes, Tips and FAQs
This guide is general information, not financial, tax, legal or medical advice. Figures use 2025/26 UK rates where relevant. Always check GOV.UK or NHS.uk for official guidance.