Planning a UK road trip and want to know what it will cost in fuel? The maths is simpler than it looks, and a few easy decisions before you set off can knock real money off the total.
Quick answer: To work out your journey fuel cost, divide the trip distance by your car's mpg, multiply by 4.546 to convert gallons to litres, then multiply by the price per litre. The biggest savings come from filling up cheaply before you leave (avoiding motorway services) and driving smoothly. Use our fuel cost calculator to do the sums instantly.
How to work out fuel cost for a trip
You need just three numbers: the distance, your real-world mpg, and the price per litre.
Here is the manual method, step by step:
- Distance — the round-trip mileage, including any detours.
- Gallons used — divide distance by your mpg.
- Litres used — multiply gallons by 4.546.
- Total cost — multiply litres by the price per litre, then divide by 100 for pounds.
So a 250-mile trip in a car doing 50 mpg uses 5 gallons, or about 22.7 litres. At a pump price of 134.9p that's roughly £30.65 each way.
Rather than reach for a calculator at the kitchen table, drop your details into our fuel cost calculator. Enter the distance, your mpg and the current price, and it returns the total for the trip. For multi-stop or return journeys, the journey planner maps the route and totals the fuel cost for you.
Example fuel costs for common UK trips
These figures assume 50 mpg and an example price of 134.9p a litre. Your real cost will depend on today's prices, your car and your driving, so treat them as a guide.
| Route (one way) | Approx miles | Litres used | Approx cost |
|---|---|---|---|
| London to Manchester | 200 | 18.2 | £24.50 |
| Birmingham to Cardiff | 115 | 10.5 | £14.10 |
| Edinburgh to Glasgow | 50 | 4.5 | £6.10 |
| Bristol to London | 120 | 10.9 | £14.70 |
| Leeds to Newcastle | 95 | 8.6 | £11.65 |
Double these for the return leg, and add a margin for traffic and detours, which always push real-world fuel use higher than the textbook figure.
Where you fill up matters more than you think
The single easiest saving on any road trip is choosing the right place to fill up. The same fuel can vary by 15 to 20p a litre between a cheap supermarket and motorway services on the same day. On a 60-litre tank, that's around £12 gone for nothing.
A simple plan beats luck:
- Brim the tank before you go at a competitively priced local station. Check today's live prices on our find the cheapest fuel near you map first.
- Avoid motorway services for fuel unless you are genuinely running low.
- Top up just off the motorway at a supermarket in a town a mile or two from the junction if you need more.
- Plan a cheap refuel near your destination if it's a long stay.
If your route crosses different regions, it's worth a quick look at fuel prices by city to spot where fuel is cheapest along the way, and you can compare two areas to decide which side of a long stretch to fill up.
Cut your fuel use, not just your price
Even with a cheap fill-up, how you drive decides how far that tank goes. These habits routinely save 10 to 20 percent on a long trip:
- Ease off the speed. Fuel use rises sharply above about 60 to 65 mph. Dropping from 80 to 70 on a long motorway run makes a noticeable difference.
- Smooth it out. Gentle acceleration and reading the road to avoid harsh braking keeps the engine efficient.
- Check your tyres. Underinflated tyres increase drag and burn more fuel. Set them to the loaded pressure for a trip with luggage.
- Lose the drag. Remove empty roof boxes and bike racks; they hammer your economy at speed.
- Pack light. Extra weight means extra fuel, so clear out the boot.
- Use cruise control on flat, steady stretches to hold an efficient speed.
Budgeting the whole trip
For an accurate budget, build in a buffer. Real-world mpg is usually below the official figure, motorway speeds use more fuel, and traffic, hills and air conditioning all add up. Adding 10 to 15 percent to your calculated cost gives you a realistic figure.
If you take regular trips, log your fills in your garage to see your true average mpg over time. That real number, rather than the optimistic showroom figure, makes every future estimate far more accurate.
The bottom line
Working out road trip fuel cost is straightforward: distance divided by mpg, converted to litres, times the price. But the real wins are in the planning. Fill up cheaply before you leave, dodge the motorway premium, and drive smoothly to stretch every litre.
Get your numbers nailed down with the fuel cost calculator, map your route in the journey planner, and find the cheapest fill-up before you set off on our find the cheapest fuel near you map.
Frequently Asked Questions
How do I calculate the fuel cost for a road trip?
Divide your trip distance by your car's mpg to get gallons used, multiply by 4.546 to get litres, then multiply by the price per litre. A fuel cost calculator does all of this for you in seconds.
How much does fuel cost for a 300-mile trip?
At 45 mpg, a 300-mile trip uses about 30 litres, so the cost depends on the pump price you pay. Always check today's live prices, as filling up cheaply before you set off can save several pounds.
What is the cheapest way to fill up before a long journey?
Fill up at a competitively priced supermarket or local forecourt before you leave, and avoid motorway services, which are often 15 to 20p a litre dearer.
Does driving style affect road trip fuel cost?
Yes, significantly. Steady speeds, gentle acceleration, correct tyre pressures and removing roof boxes can cut your fuel use by 10 to 20 percent on a long trip.
Should I fill up before or after the motorway?
Before, if you can. Motorway services charge a premium, so topping up at a cheaper station near home or just off the motorway usually works out far better value.