Travel Distance & Time
Calculate travel time and fuel cost for a road trip at any speed.
MCA Yachtmaster Ocean, MNZ Coxswain (restricted)
Offshore sailing instructor and maritime educator with 30 years of blue-water passages. Author of coastal navigation guides for NZ waters.
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About the Travel Distance & Time
Planning a road trip involves three interrelated variables: distance, time, and cost. The naïve calculation — divide distance by speed — consistently underestimates journey time because it ignores stop time (fuel, food, rest), traffic delays, and the physical reality that motorway average speeds rarely match the speed limit. The UK Highway Code recommends stopping for at least a 15-minute break every 2 hours; the Highway Code also notes that driver fatigue contributes to around 20% of road accidents on motorways and monotonous roads. Planning realistic stop time is both safety-critical and practically important.
Fuel cost is a significant component of road trip economics. The default fuel consumption of 7L/100km reflects UK average petrol car consumption in mixed driving. Modern turbocharged engines often achieve 5.5–6.5L/100km at constant motorway speeds, but this rises sharply in traffic (stop-start driving increases consumption by 40–70%). Diesel engines typically use 15–20% less fuel by volume but diesel fuel prices have often been higher than petrol in the UK since 2022, partially offsetting the efficiency advantage. Electric vehicles don't use L/100km — their equivalent is kWh/100km (approximately 15–18 kWh/100km for most EVs), with energy costs around 30–35p/kWh for home charging.
The fuel economy of your specific vehicle is the single biggest variable in the cost calculation and can be found on your car's onboard computer (trip computer, usually displayed in the instrument cluster), the official test data from the manufacturer's website (though real-world is typically 15–25% worse than official WLTP figures), or from crowd-sourced real-world data at sites like Spritmonitor.de or Fuelly. Using accurate fuel consumption data rather than the default can change the calculated cost by 30–50% on a long trip.
How it works
Driving Time = Distance ÷ Average Speed Total Time = Driving Time + Stop Time Fuel Used = (Distance ÷ 100) × Consumption (L/100km) Fuel Cost = Fuel Used × Price per Litre
Worked example
London to Edinburgh road trip: 668 km, average speed 90 km/h (motorway with some congestion).
Driving time = 668 ÷ 90 = 7.42 hours = 7h 25m.
Stop time: 3 stops × 20 minutes = 60 minutes.
Total time = 7h 25m + 1h = 8h 25m.
Fuel: 7L/100km × 6.68 = 46.8L.
Cost at £1.55/L: 46.8 × £1.55 = £72.50 in fuel.
Split two ways: £36.25 each — comparable to a standard train but with flexibility and door-to-door convenience.
Tips to improve your result
- 1.
The AA recommends maintaining awareness of tiredness with the "yawning test": if you've yawned three or more times in 15 minutes while driving, pull over. Tiredness impairs reaction time similarly to alcohol — tired driving at the legal limit is effectively equivalent to drink driving.
- 2.
Google Maps and Waze routing uses real-time traffic data but tends to underestimate journey times for unfamiliar routes by 10–20%. Add a 15% buffer to any ETA for important journeys (flights, appointments).
- 3.
Fuel costs drop significantly on long motorway stretches vs urban driving. If your route includes significant urban driving at the start or end, increase the L/100km figure by 20–30% for a more accurate total cost estimate.
- 4.
Motorway service station fuel is consistently more expensive (up to 30p/L more) than supermarket or local filling stations. On a long trip, filling up before joining the motorway and again near the destination (at a supermarket) can save £15–20.
- 5.
For electric vehicles: plan charging stops using the Zap-Map app for the UK (most comprehensive public charging database). Fast chargers (50–150 kW) are at most motorway services; ultra-rapid chargers (150–350 kW) at selected BP Pulse and Gridserve locations can add 100+ miles of range in 15–20 minutes.