Why use this calculator
Most road trip plans fail on time rather than money. A maps app quotes the drive at the speed limit with no stops, but real trips include towns, roadworks, fuel, food, toilet stops and the rest breaks that road safety agencies in Australia, the UK and the US all recommend.
Leave those out and a trip planned as one long day becomes a tired night drive, which is when fatigue crashes happen. This calculator builds the day honestly. It uses a realistic average moving speed, adds a 15 minute break for every two hours at the wheel, adds your meal and sightseeing stops, and splits the driving into days at a limit you choose.
It also works out fuel cost and how many times you will need to refuel given your tank, keeping a quarter tank in reserve, which matters on remote Australian and American highways where stations are far apart.
How to use it
- Pick your units: metric, US or UK.
- Enter the total distance from a maps app, adding a margin for detours.
- Enter your expected average moving speed, which should sit below the highway limit. Enter your fuel economy for highway driving. Enter the average fuel price along the route.
- Enter the usable fuel tank size from the owner's manual.
- Enter how many extra stops you plan for meals or sightseeing beyond the recommended rest breaks.
- Enter the average length of those stops in minutes.
- Finally set the most hours you are willing to drive in one day.
What each result means
- Total trip time
- Driving time plus rest breaks plus your extra stops. This is the figure to plan departure and arrival around.
- Drive time
- Time with the wheels turning at your average moving speed, before any breaks or stops are added.
- Days on the road
- How many days the driving takes at no more than the daily hours you set. Overnight stops are not added to trip time.
- Recommended rest breaks
- Fifteen minute breaks, one for each two hours of driving, as road safety agencies in Australia, the UK and the US advise.
- Time in your extra stops
- The total of your planned meal and sightseeing stops, separate from the recommended rest breaks.
- Refuelling stops
- How many times you need to refuel after starting full, refilling when a quarter of the tank is left.
- Total fuel cost
- Fuel for the whole distance at your economy and the average price you entered along the route.
- Fuel needed
- Litres, or US gallons in US mode, the whole trip will burn at your fuel economy.
- Running cost per distance
- The fuel cost of each kilometre or mile, useful for comparing against flights or splitting costs.
The formula
Drive time
(min) = distance / average speed x 60
Rest breaks = round up (drive time / 120) - 1, each 15 minutes, following the guidance to rest every two hours
Total trip time = drive time + rest breaks + extra stops x stop length
Days = round up (drive time / (hours per day x 60))
Fuel (L) = L/100km / 100 x km
Range = 75 per cent of tank / (L/100km / 100)
Refuelling stops = round up (km / range) - 1, starting with a full tank
How this number is used in practice
Fatigue is a leading factor in fatal crashes on long country drives. Australian road safety agencies, the UK Highway Code and the US National Highway Traffic Safety Administration all advise a break of at least 15 minutes every two hours, and warn that the risk climbs sharply after a normal day's work, in the mid-afternoon dip and between midnight and 6 am.
Sharing the driving helps, but a passenger who has been asleep is not instantly alert either. Planning the trip over two days is often safer and cheaper than it looks once a night's accommodation is weighed against the risk.
Average moving speed is always lower than the speed limit. On Australian country highways with 100 or 110 km/h limits, towns, roadworks, overtaking lanes and trucks usually bring the average to 85 to 95 km/h. On US interstates, 60 mph is a realistic average with a 70 mph limit, and in the UK a mix of motorway and A-roads averages around 50 mph. Use a lower figure for mountain roads, caravans and holiday traffic.
In remote Australia and parts of the western US, fuel stations can be 200 to 300 km apart and may close at night. Refuel whenever you pass one below half a tank, and carry water. Fuel prices in these areas can run well above city prices, so budget on the high side.
Worked examples
A 1,600 km outback leg at 90 km/h, 8 L/100km, $1.90, 55 L tank, two 45 minute meals
17 h 47 min driving, 8 rest breaks, 21 h 17 min in total over 3 days, 3 refuelling stops and $243.20 in fuel
A US 1,000 mile trip at 60 mph, 28 mpg, $3.50 a gallon, 14 gallon tank, 3 meal stops of 40 minutes
16 h 40 min driving, 20 h 40 min in total with 8 rest breaks over 3 days, 3 refuelling stops and $125.00 in fuel
A UK 450 mile run to Scotland at 55 mph, 45 UK mpg, £1.45 a litre, 50 L tank, one 45 minute stop
8 h 11 min driving, 9 h 56 min in total with 4 rest breaks, 1 refuelling stop and £65.92 in fuel
When people use it
- Planning departure times so you arrive in daylight
- Deciding whether a long drive should be split over two days
- Budgeting fuel for a holiday or a house move by car
- Checking whether the car's range covers remote stretches between towns
- Comparing drive time and cost against a flight
Tips
- Stop for at least 15 minutes every two hours, and swap drivers if you can.
- Avoid driving between midnight and 6 am and in the mid-afternoon slump when fatigue peaks.
- Refuel below half a tank in remote areas. The next station may be closed or far away.
- Use an average speed 10 to 20 per cent below the limit for a realistic arrival time.
- Check tyre pressures and fluids before leaving. A loaded car needs the higher placard pressure.
- Download offline maps before leaving mobile coverage on country highways.
What it assumes, and where it stops being accurate
- The average speed applies to the whole trip. Cities, roadworks and mountain sections all reduce it.
- Rest breaks are 15 minutes every two hours. Fatigued drivers need longer breaks or a sleep.
- Overnight stops split the driving into days but are not added to the trip time figure.
- Refuelling starts from a full tank and refills at a quarter tank. Station spacing is not checked.
- Fuel economy and price are constant along the route.
- Tolls, accommodation, food and wear on the car are not costed.
Terms used on this page
- Average moving speed
- Distance divided by the time the car is actually moving, excluding stops.
- Driver fatigue
- Tiredness that slows reaction and judgement, a major factor in country road crashes.
- Usable tank
- The fuel you can draw before the tank is empty, usually close to the stated capacity.
- Range
- How far the car travels on the fuel available between refills.
Questions people ask
- How often should I take a break when driving?
- Road safety agencies in Australia, the UK Highway Code and US safety bodies recommend a break of at least 15 minutes every two hours. Stop sooner if you yawn repeatedly, drift in the lane or miss signs. Those are signs of fatigue, and only sleep fixes it.
- What average speed should I use?
- Use a figure 10 to 20 per cent below the speed limit. For Australian country highways, 85 to 95 km/h is realistic. US interstate trips average about 60 mph, and UK trips mixing motorways and A-roads around 50 mph. Use lower figures when towing.
- How many hours can I safely drive in a day?
- There is no legal limit for private drivers in most places, but road safety advice is to avoid more than about 8 to 10 hours at the wheel in a day. Heavy vehicle drivers are legally limited, which shows how seriously fatigue is taken.
- How are refuelling stops worked out?
- The calculator takes 75 per cent of your usable tank as the range between fills, so you refuel with a quarter left. It divides the trip by that range and subtracts one because you start full. On remote routes refuel more often than this.
- Is driving cheaper than flying?
- For two or more people, often yes on fuel alone. Add accommodation, meals, tolls and wear on the car, and value the extra days, before deciding. The running cost per distance here is fuel only, and full car running costs are several times higher.
Use this with
Road Trip Planner Calculator answers one part of the question. These pick up where it stops: Fuel Cost Calculator, Fuel Efficiency Calculator, Speed Distance Time Calculator and Moving Cost Estimator.
Where these figures come from
This calculation is jurisdiction-neutral arithmetic. No country-specific rules are applied.
- UK Government: The Highway Code. Rule 91 on driver fatigue and breaks every two hours
- National Highway Traffic Safety Administration. US drowsy driving research and guidance
- US Department of Energy and EPA: fueleconomy.gov. Trip fuel cost and economy guidance
Road Trip Planner Calculator produces an estimate for general information. It is not financial, tax, medical, legal or engineering advice. read the full disclaimer. Spotted a wrong number? Report it and it gets fixed. The form picks up this calculator and the inputs you used.