Road trip stops:
working out refuels from distance and range

Legs and stops: the rounding-up rule

A road trip divides into legs, each as long as one tank allows. The number of legs is the distance divided by the range, rounded up to the next whole number, because even a short final stretch needs fuel. The number of refuelling stops is one fewer than the number of legs, since you start with a full tank.

When the distance is an exact multiple

An exact multiple such as 800 km on a 400 km range gives 2 legs and 1 stop, but you would arrive at the stop with a completely empty tank. That is not a plan, it is a gamble. The next section shows how to avoid it.

Plan on less than the full range

Nobody should schedule a refuel for the moment the needle hits empty. Fuel stations may be closed, queues may be long, or a diversion may add kilometres. A cautious planner uses 75% to 80% of the range as the working leg length.

Using 80% of 400 km gives 320 km legs. The 950 km trip then divides by 320, which is 2.97, rounded up to 3 legs and still 2 stops. At 75%, legs are 300 km, 950 ÷ 300 = 3.17, rounded up to 4 legs and so 3 stops. The reserve changes the answer, and it does so in a way that is easy to miss on a long route.

Choosing where to stop

The arithmetic tells you how many stops, not where. Once you know the leg length, mark the point where each leg would end on the route and then look for a fuel station before that point, not after it.

• Look at the map for reliable stations around the 70% mark of each leg, so you can skip one if it looks poor and still reach the next.
• Combine a fuel stop with a meal or rest break; many drivers need a break every two hours anyway.
• On routes with sparse stations, top up at the last good opportunity even if the tank is not low.
• Check opening hours if you drive at night.

What stops do to total journey time

Each stop adds time: leaving the road, queueing, refuelling, paying and rejoining. Fifteen minutes per stop is a reasonable planning figure, with more for a meal break.

For the 950 km example at an average speed of 80 km/h, driving takes about 11.9 hours. Two 15-minute stops add half an hour, so the trip is about 12.4 hours; three stops add 45 minutes, for about 12.6 hours. A trip-time calculator helps combine driving time with stops, and the fuel trip cost tool puts a rupee total on the fuel you will need.

Adjusting the plan for a night drive

Night driving changes the plan in two ways. Fewer stations are open on some roads, and drivers get tired sooner. A sensible adjustment is to refuel earlier, at around 60% of the range, and to plan the rest stops on the same schedule.

With a 400 km range and a 60% planning share, each leg is 240 km. The 950 km trip then divides to 3.96, which rounds up to 4 legs and 3 stops. The extra stop costs about fifteen minutes, which is a small price for not hunting for an open pump at 2 a.m.

Combining fuel stops with driver changes

If two people share the driving, line up the refuel with the swap. Each leg of about 300 km is roughly three to four hours on the road, a reasonable shift. That way the stop does double duty: the car is refuelled while the driver rests, and nobody loses extra time.

On a 950 km trip with 4 legs of about 238 km each, the legs come out to under three hours at highway speeds, which fits a comfortable rotation. Dividing the distance by the number of legs, instead of filling each leg to the limit, spreads the load evenly.

A short checklist before you set out

1. 1Decide your planning range, usually 75% to 80% of the full-tank range.
2. 2Divide the distance by that leg length and round up.
3. 3Mark the end of each leg on the route and find a station ahead of it.
4. 4Add 10 to 15 minutes per stop to the travel time.
5. 5Carry a payment method that works across states, and keep a little cash for rural pumps.

Adjusting the range for the real trip

The range you plug in should be what your vehicle gets on this trip, not the brochure number. Steady highway driving usually does better than the city figure, but a heavily loaded vehicle, roof carriers or mountain roads can pull it down.

If your normal mixed range is 400 km but the trip is mostly flat highway, you might raise your planning range a little. If you are crossing hills with luggage, reduce it. Re-run the numbers with the revised range. The formula is simple; the skill is in choosing a realistic input.