When you’re busy planning a road trip, it’s easy to forget about the costs of seemingly minor expenses like gas and tolls. This guide will help you avoid that rather unpleasant surprise by teaching you how to calculate gas costs for a road trip, and how to find the perfect rental car for the journey.

Gas price estimator for road trips

While you can certainly bring out a pen, pencil, and calculator to determine a gas estimate for your road trip, AAA’s handy gas cost calculator can tell you in seconds. It works by using current national average gas prices, your vehicle’s miles per gallon (how far it can travel on a gallon of fuel, also called MPG), and the distance you plan to drive. 

If you’re going to rent a car for your trip, you can use the MPG numbers below for nine popular gas-powered rental car models.

How to calculate gas costs for a road trip

We’ve been talking a bit in the abstract so far, so let’s see what these calculations actually look like in action. Below we mapped out three fun trips around the US and have broken down the price of gas by vehicle type, using its highway MPG. These numbers should give you a sense of how much you may need to put aside for gas for your own trip.

335 miles – San Diego to Las Vegas road trip

One-way drive time: ~5 hours

Drive through desert landscapes and take a detour or two into a national park as you travel from coastal San Diego to lively Las Vegas. This 335-mile journey is an unforgettable road trip. With just a one-hour detour of ~50 miles, you can add Joshua Tree National Park to your itinerary (not included in the below gas estimate for this road trip).

500 miles – Dallas to New Orleans road trip

One-way drive time: ~7.5 hours

This route is filled with Southern charm, delicious eats, and historic neighborhoods. The drive from Dallas to New Orleans clocks in at about 500 miles and makes for a perfect multi-day escape.

2,778 miles – New York City to Los Angeles road trip

One-way drive time: ~41 hours

This cross-country adventure from New York City to Los Angeles is one of the ultimate American road trips. You’ll pass by so many roadside attractions and tempting turnoffs that the 41-hour drive estimate will be laughable by the time you’ve actually reached your destination. Have fun with it and enjoy the long journey!

Factors affecting fuel efficiency

Gas mileage can vary more than you’d think. From what you drive to how you drive, the following key factors all play a role when estimating gas for a road trip.

1. Vehicle type

Smaller cars tend to use less gas than larger ones. If you’re in a compact sedan, for example, you’ll generally get better mileage than if you’re in a truck or SUV.

2. Driving habits

Driving smoothly and continuously — avoiding sudden stops and starts — can help save gas and reduce wear and tear on the vehicle. It’s good for your wallet and your car.

3. Road conditions

Driving uphill requires more power and fuel than driving on a flat surface, while stop-and-go traffic can also lower your fuel efficiency. Instead, opt for routes with smoother terrain and less congestion to improve your vehicle’s gas mileage.

4. Maintenance and tune-ups

Well-maintained vehicles use less fuel, so ensure your car has been tuned up before driving off. Then while on the road, keep tires properly inflated and air filters clean to help your engine run efficiently.

5. Load and cargo

Heavier cars burn through more gas, as more power is needed to move the vehicle. This means more stops and more spending. Try to pack light to save fuel, especially on longer trips.

6. Fuel quality

Using the right fuel for your car matters. Stick to your car’s recommended octane rating for optimal performance and efficiency, helping your budget stretch further on the road trip.

Tips for saving money on gas

Want to stretch your gas dollars further? These smart tips can help cut down on costs.

1. Drive a fuel-efficient vehicle

When buying or renting a car, it’s important to think about the MPG (miles per gallon) rating. Smaller or lighter vehicles typically get more miles per gallon, while trucks and SUVs burn through gas quicker. You may even consider renting a hybrid or fully electric vehicle to further reduce fuel costs.

2. Plan your route carefully

Use apps like Waze or Google Maps to plan the most efficient and optimal route for your road trip. You can select options like avoiding tolls, add multiple stops, and get real-time traffic updates.

3. Maintain optimal tire pressure

Properly inflated tires improve fuel efficiency by reducing rolling resistance. Even when you’re not planning a road trip, it’s important to check your tire pressure regularly, and inflate them to the manufacturer’s recommended pressure.

4. Use cruise control

On highways or long stretches of open road, cruise control helps maintain steady speeds. This means less fuel wasted on sudden acceleration or deceleration.

5. Close windows and use air conditioning

When driving at higher speeds, open windows create drag, which forces the engine to work harder and consume more fuel. Instead, use the AC to keep things cool without sacrificing fuel efficiency.

6. Consider fuel rewards programs

Many gas stations and grocery store chains offer points or discounts on gas purchases. Sign up to save every time you fill up on your road trip.

7. Stay on top of vehicle maintenance

Properly maintaining your vehicle can help keep your gas budget down. A well-tuned engine, clean oil, and fresh filters can make a noticeable difference in fuel efficiency.

8. Carefully select gas stations along the route

Prices can vary quite a lot between stations, even in the same local area. Use fuel price comparison apps like GasBuddy to find the cheapest options and plan your road trip route accordingly.

9. Carpool or use public transportation

If you’re traveling with others, share a ride and split the gas budget. What’s more, fewer cars on the road means less congestion and lower overall fuel usage — leading to lower costs.

Final thoughts: Estimating gas for a road trip

Estimating your gas cost before a road trip helps you budget smarter and stay aware of your fuel use, which is especially helpful if you're watching your spending. You can use a helpful tool like AAA’s gas calculator to quickly calculate gas cost for your road trip, and you’re done! By taking a few minutes to estimate your fuel expenses, you can ensure a smoother, more budget-friendly road trip.