How to Split Gas Money Fairly Between Friends

Splitting gas money sounds simple until someone brings up wear and tear, different fuel prices, or the fact that one person drove twice as far as everyone else. Here's how to do it right, whether you're carpooling to work or roadtripping across the country.

THE SIMPLE FORMULA

The fairest way to split gas costs is based on actual fuel consumed, not a flat rate or rough guess. Here's the formula that works for any vehicle:

For a gas car, fuel efficiency is measured in L/100km (or you can convert from MPG). For an electric vehicle, it's kWh/100km. The fuel price is whatever you're paying per litre of gas or per kWh of electricity.

STEP-BY-STEP EXAMPLE

THREE COMMON METHODS

1. ACTUAL COST SPLIT (RECOMMENDED)

Use the formula above. Calculate what the trip actually cost in fuel and divide it equally. This is the fairest method because it accounts for the specific vehicle's efficiency and current fuel prices.

2. FLAT RATE PER PERSON

Agree on a fixed amount per person per trip (e.g., "$10 every time"). This is simpler but often unfair, especially if distances vary or fuel prices change. It tends to either overcharge or undercharge passengers.

3. "I'LL DRIVE NEXT TIME"

Taking turns driving so costs roughly balance out over time. Works well for two-person carpools with similar commutes, but breaks down quickly with groups of three or more, or when one person drives more often.

WHAT ABOUT ELECTRIC VEHICLES?

The same formula works for EVs. Just swap the units:

Yes, EVs really are that cheap per trip. That's why splitting EV costs often feels pointless for short trips, but it adds up over months of daily commuting.

HANDLING MPG INSTEAD OF L/100KM

If you think in miles per gallon, convert to L/100km first:

So a car rated at 30 MPG (US) is about 7.84 L/100km. Once converted, use the same formula as above.

COMMON MISTAKES

1. Only counting gas money, not round trips. If someone drove you to the airport, that driver also had to drive home empty. Account for the full round trip.
2. Using the sticker fuel economy. Real-world efficiency is often 10-20% worse than the manufacturer's rated number, especially in city driving or cold weather.
3. Splitting by distance driven, not cost. Two equal-distance trips can have very different costs if one was in highway conditions and the other in stop-and-go traffic.
4. Forgetting the driver pays too. The driver is also a rider. If there are 4 people in the car including the driver, divide by 4, not 3.
5. Not tracking over time. One-off splits are fine, but for regular carpools, a running balance is essential for fairness.

WHAT ABOUT WEAR AND TEAR?

Some people argue that passengers should also contribute to vehicle maintenance, tire wear, and depreciation. While technically fair, this overcomplicates casual cost splitting and can create friction between friends.

Our recommendation: stick to fuel costs only for casual carpools. If you're running a more formal rideshare or commute arrangement, the CRA's per-kilometre rate ($0.72/km for the first 5,000 km in 2026) is a reasonable all-in number that includes wear and depreciation.

TIPS FOR FAIR SPLITTING

• Agree on the method before the trip, not after
• Use actual fuel prices, not estimates
• Account for return trips when relevant
• Track costs over time instead of settling every single trip
• Use an app to remove the awkwardness of asking for money
• Be generous on rounding — don't fight over $0.37

THE BOTTOM LINE

Splitting gas money fairly comes down to one principle: calculate the actual cost and divide it equally among everyone in the car. The formula works for gas, diesel, hybrid, and electric vehicles. The hardest part isn't the math — it's remembering to do it consistently.

That's why apps that automate the calculation and track running balances between friends make the whole process painless. No spreadsheets, no mental math, no awkward "so you owe me..." texts.