How Many Hours a Day Should You Actually Drive?
Multi-day drives fail on fatigue rather than distance, and the arithmetic that prevents it is worth doing before setting off.
A worked plan
The road trip planner splits a distance into days under a daily driving cap and works out the break time. For 2,400 km at an average 90 km/h, capped at 8 driving hours a day with a 20-minute break every 2 hours:
- 26.67 hours of driving in total
- 4 driving days, averaging 600 km each
- 13 breaks, totalling 4.33 hours
That last figure is the one people leave out. Four and a third hours of breaks across the trip is more than half a driving day, and a plan that ignores it arrives late every single day.
Average speed is not the limit
Ninety km/h as an average across a driving day is not a modest figure — it implies very little traffic, few towns and no delays. Motorway cruising speed and trip average speed are different numbers, and the gap is where plans go wrong.
The honest approach is to use a lower average than feels right. If a previous trip on similar roads averaged 75 km/h door to door, that is the figure to plan with regardless of what the speed limit says.
Why the daily cap matters more than the total
Driver fatigue is the largest controllable risk on a long drive, and its effect is on reaction time — which, as the stopping distance calculator shows, is the biggest thing a driver controls. At 100 km/h the difference between a 0.7-second and a 2.5-second reaction is 50 metres of stopping distance.
A tired driver does not brake less hard; they start braking later, and the delay is spent at full speed. That is the mechanism, and it is why an eight-hour cap is a safety input rather than a comfort preference.
Breaks are not optional slack
The break cadence in the planner — every two hours — matches the general advice given by most road-safety bodies. The point is to interrupt the fatigue accumulation rather than to rest once it has arrived.
A break that involves getting out of the car and moving does considerably more than one spent sitting at a service station looking at a phone. And if a break is not helping, that is a signal to stop for the day rather than to push to a planned destination.
Building rest days in
The planner takes a rest-day count for a reason. On trips beyond three or four driving days, a non-driving day is usually faster overall than the alternative, because the days either side of it are better.
It also creates slack. A trip planned with no spare days has no way to absorb weather, a closure or a slow morning, and the pressure to make up time is exactly the pressure that produces long days.
For an EV, plan charging into the day
Charging stops and breaks are the same stops if you plan them together. Twenty minutes on a 150 kW charger for a 20–80% top-up is close to the break cadence anyway — but only if the stop is where you need it.
Planning arrivals at 10–20% rather than at zero, and knowing the next charger before leaving the last one, converts charging from a constraint into part of the rhythm.
Who is driving matters as much as how far
A two-driver trip is a different plan from a one-driver trip, and swapping at breaks is more effective than swapping when someone is already tired. The daily cap applies to each driver, not to the vehicle.
Sleep before the trip matters more than most people credit. Starting a long drive already short of sleep moves reaction time in exactly the direction the stopping-distance arithmetic punishes.
The last hour is the dangerous one
Fatigue accumulates, and the final stretch of a long day is where a plan's optimism gets paid for. Planning to arrive with daylight and margin, rather than to a fixed time, removes the pressure that produces that last hour.
If a break stops helping, that is the signal to stop for the day — and a plan with a spare day in it makes that an easy decision rather than an expensive one.
Reaction time is the part of stopping distance that belongs entirely to the driver, and the Stopping Distance Reference Table shows exactly what it costs: at 100 km/h, the gap between an alert reaction and a tired one is about 50 metres of road covered before the brakes have done anything.