What this calculator does
The Carpooling Savings Calculator estimates how much fuel a trip uses, what it costs in total, and how that cost drops once you split it between everyone riding in the car. It is a universal tool — it works with any currency and any distance unit as long as you keep your inputs consistent (kilometres with km-per-litre, or just adapt the labels for miles and gallons).
How to use it
Enter the one-way (or round-trip) distance, your vehicle's fuel efficiency in kilometres per litre, the current fuel price per litre, and how many people are in the car. The calculator returns the cost each person should pay, the total fuel cost, the litres burned, and how much you personally save compared with driving the route alone.
The formula explained
First the fuel used is distance ÷ efficiency. Multiplying by the price per litre gives the total fuel cost. Dividing that by the number of passengers gives each person's fair share:
$$\text{Cost per Person} = \frac{\dfrac{\text{Distance (km)}}{\text{Efficiency (km/L)}} \times \text{Price (per L)}}{\text{People}}$$
Worked example
Suppose four people drive 100 km in a car doing 12 km per litre, with fuel at 1.50 per litre. Fuel used = \(100 \div 12 = 8.33\) litres. Total cost = \(8.33 \times 1.50 = 12.50\). Split four ways, each person pays \(12.50 \div 4 = 3.13\), and each saves \(12.50 - 3.13 = 9.38\) compared with driving alone.
FAQ
Should I include the driver as a passenger? Yes — the "people in car" field is everyone sharing the trip, including the driver, so costs are split fairly among all occupants.
Does this include tolls, parking or wear? No, this calculator covers fuel only. Add other shared costs separately and divide them the same way.
Can I use miles and gallons? Yes. Enter distance in miles, efficiency in miles per gallon, and price per gallon — the maths is identical.
