When RVing, The Best Gas Mileage Calculator Is YOU

by frugalrvers

We will show you how to calculate gas mileage and how to figure how much gas you need for a trip, to help keep that rv fuel cost travel budget accurate!

When traveling in an rv, you have to have an accurate fuel cost calculator - and that would be you! No matter if you are rving in a travel trailer or driving a motor home, you can expect to get poor mpg in almost any conditions. These heavy recreational vehicles drink up gasoline, so be prepared for that shock at the gas pump. Fuel efficiency gets even worse when you are going up hills or battling windy conditions, and you can't plan for those things very well, so it is even more important that your Point A to Point B basic fuel mileage calculation is accurate.

Fuel Calculation A Must In The Frugal RV Lifestyle

When you live a cheap rv lifestyle as we do, it is extremely important that we don't run out of funds before reaching our destination. We cannot afford unexpected surprises so we calculate gas mileage as accurately as possible.

Years ago, we completed an 1,800 mile trek from northwest Montana to Illinois in a "new to us" 1993 Fleetwood Bounder, Class A motorhome. As full time rvers, we weren't new to the gasoline expense of these long distances, but we had never done it in our Bounder. We had a lightweight travel trailer our first few years on the road, and got poor mileage towing that camper. It should, therefore, come as no surprise that we were terrified to try to figure out what mpg we would get with a motorhome. Though we stayed at cheap or even free campgrounds along the way, to help cut costs, we knew we had to calculate distance and gas mileage accurately, to be sure we had the funds for this trip.

Actually, we were quite surprised to see that our large Class A was almost identical to the gas mileage we got pulling the travel trailer. This rving is certainly a "learn as you go" deal.

So let's get rolling and show you what we do...........

TIP - Don't Calculate Gas Cost Without Properly Inflated Tires

Tire Pressure Gauge - 0 to 170 PSI - ...

How To Figure Gas Mileage - Basic MPG Calculator Steps

The first step is figuring your gas mileage, and you will be amazed at how simple the process truly is. The gas mileage calculation formula is posted below:

  1. Fill your vehicle's gas tank completely. It doesn't have to be overflowing, but make sure it's right up to the top. Then when you are back in the driver's seat and before you leave the gas station, make a note of the current mileage on your odometer.

  2. You should then put at least 100 miles on your rv in driving conditions you expect to encounter (think city vs. highway miles). When you are close to a hundred miles later (you didn't lose the note, did you?), go to your favorite gas station and fill up just like you did before.

  3. Write down how many gallons you put in to the tenth (3.1 gallons, for example) and then subtract the old mileage on the odometer from the new. Take this number of miles and divide it by gallons used (you can use a calculator). the result will be your vehicle's MPG.

So now you know how to calculate the BASELINE gas mileage you will actually get from your rv. It is extremely important that before you drive long distances, you take your rv on the road for a few hundred miles, to get a baseline for mpg you can expect from your vehicle. You should keep a gasoline journal always so you can keep track of your average mpg, in many conditions, to get to know your rv's fuel consumption intimately.

You Can Keep A Fuel Cost, Mileage Journal.......

AT-A-GLANCE Auto Mileage Log Record Book, 3.75 x 6.12 Inches, Black...

Gas Cost Calculator PROBLEMS To Watch Out For - Add A "Buffer" To That Number

It was mentioned above that the basic miles per gallon calculation above gave you a general baseline. But things can go terribly wrong if you stick to just that number. For simplicity, let's assume that we calculated we get 10mpg. But sticking to that number could turn our budget upside down! Here are the potential problems:


If you are driving your EMPTY rv around that you just got off the lot, you are in for a real surprise once you load it up with your possessions, because your gas mileage will plummet. The best suggestion is to calculate your miles per gallon baseline only when fully loaded.


Here is the good and bad news about wind - it can make for very happy rvers, or very depressed rvers! We hit a wind across the Dakotas one time that was like a hurricane - and we drove into that wind for hours and hours and hours. It would not let up and, not kidding, our gas gauge needle went from full to empty in no time - we were using double the gasoline we had been.

If you hit a really bad wind like that for a long duration, it is going to hurt until you are out of it. Probably more economical to pull off the road and stay at a campsite until it passes! However, we have had bad, gusty winds BEHIND us and "yeeee-hawwww!!!" that gas gauge needle barely moved - more money in our pockets! The point is, you have to adjust your baseline for mother nature's gas guzzling windstorms.


If you are about to embark on a trip through the Rockies, do keep in mind you will burn a lot of fuel going up. But never underestimate the "hilly country" either. Sure, you coast down the other side, but we really see our fuel efficiency decline in hilly terrain.


So what to do about these potential issues? I always err on the side of caution. If my baseline is 10mpg fully loaded and I am driving 1,000 miles across pretty flat terrain, I would probably go with 8-9 mpg as my fuel calculation. But if I am about to go through many mountains and hills, I might bring it down to 7mpg. Here is the good news (there is some!) - if you overestimate, you will have leftover funds in the end...but if catastrophe hits (more hills than you thought, terrible winds and you just had to bring along and extra 800 pounds of books, you won't run out of money - especially when living cash only like us, that is important!

Finally, The True Road Trip Calculator - Where Miles Meet Your MPG

So now it is time to calculate your total travel costs - it is time for you to estimate the miles you will be driving - and then bring your mpg into the equation, so you can calculate gas cost for your entire trip.

Here is how we did it:

  1. Get the exact mileage, to the best of your ability, from the city you are departing from to the exact destination you will be stopping at. If a long distance trip, don't just do a "Chicago to Seattle" search on Google Maps. Plan where you will be staying and add up mileage estimates by day, from campsite to campsite, because many campgrounds can be 10 miles off the highway - that's 20 miles round trip just to and from! Be accurate and take your time on this part!

  2. Look at the average cost of a gallon of gas in each state you will be traveling through. We use the free site called GAS BUDDY. If going through five states (here is that math again), write down the 5 average gas prices, total them all, then divide by 5, which gives you the overall average you can expect to pay for gas.

  3. Now grab that MPG average you came up with (your baseline plus adjustment for weight, wind, mountains, etc.). It is time to put it altogether. For ease, I will use clean, rounded numbers for this final calculation. I am going to say that I am going exactly 2,000 miles, that I get 10mpg AND the average fuel cost is $3.00/gallon (if you don't have these three pieces of data in front of you, you missed a step somewhere!) Divide 2,000 miles by 10mpg, which is 200. This figure means you will need 200 gallons of fuel on your trip. Now, multiply these 200 gallons by the average fuel cost of $3.00/gallon - which is $600. So you can expect to pay around $600 for fuel when rving on your long distance journey! You did it!

Final Fuel Consumption Calculator, Calculate Gas Cost Thoughts

Even if you aren't unconventional, frugal rvers like us, it is doubtful any rver out there doesn't want to keep tabs on his/her expenses. In a sticks and bricks house, you know what the cost of running that house is - you get those monthly bills - it should be no different for rving folks.

If you are on a limited budget, calculating fuel costs accurately can be the difference between joy and tragedy. You have to be prepared or you could end up washing dishes somewhere in North Dakota for months to pay for gas for the rest of your trip!

Calculating fuel costs on the road is a daily practice - it isn't just for one long trip. You should have a dedicated travel journal, where you keep track of mpg at each fill up and also notate any unusual conditions that may have impacted better or worse fuel efficiency. The more you get to know your rig and its gas guzzling habits, the more you can fine tune the calculations we shared above.

Hope these gas mileage and trip calculator tips have helped. When rving across the country, you should be able to relax and enjoy the ride. Being prepared for fuel costs, instead of shocked and upset at the gas pump, will ensure a fantastic trip.

Safe Travels.................

Other RV Tips Articles We've Written

Dry rot tires on an rv tire are no laughing matter. Having survived losing two while on the highway, we do laugh at our ignorance, but want to pass on this rv safety tip to you!
Living in an rv with cats is possible - but you need to plan ahead for your feline friends. The RV cat has special needs, so be sure to read these tips!
Portable waste tanks can be a lifesaver for rvers. We will review the two most popular brands, Thetford SmartTote And Barker Tote Along, and help you decide if you need one, too!
If you care about your rv's flooring, you will soon find that an outdoor, reversible patio mat is the key to preserving the interior of your camper..just take a look at these mats!
Updated: 09/29/2018, frugalrvers
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DerdriuMarriner on 07/20/2017

frugalrvers, Do you go for the lowest, the middle or the highest price at the pump?

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