There are many ways to correctly calculate fuel consumption. Not everyone has on-board computers. Various online calculators require the input of actual data, which you still need to find out. But proven folk methods are a completely different matter. Simple. Accurate. Reliable. And the most important thing is that they are available for any interested car enthusiast.

If you already have the initial data, use the calculator to calculate: consumption per 100 km; consumption per 1 km; mileage per 1 liter of fuel; cost of 1 km of the way; the cost of a full tank; mileage on a full tank; the cost of the upcoming trip and how much fuel is needed for it.

Fuel calculator

Benefits of correct fuel consumption calculation

If you are interested in the question - how to calculate fuel consumption - you probably already have some kind of goal. However, expanding your horizons is never superfluous. Therefore, for starters, we suggest briefly considering all the benefits that a correctly measured consumption of your car gives.

Real fuel consumption allows you to find out:

  1. Do the actual figures match those declared by the manufacturer of the new, or the seller of the used car.
  2. Whether the technical condition of the engine has deteriorated.
  3. What benefits (losses) does a car used for commercial purposes bring.
  4. When gas stations are filled with low-quality fuel.
  5. How much money does 1 km of run or a specific trip cost.
  6. The amount of savings after switching from gasoline to gas.
  7. How consumption changes in winter, summer, on the highway, in the city, with a trailer, and so on.

As a result, it turns out that regular and correct control of fuel consumption for commercial vehicles is simply a must. For ordinary motorists, such calculations are often carried out solely for the sake of sports interest. Although there are those who note the runs and fuel used for practical purposes. For example, to indirectly monitor the condition of the engine, the quality of service at gas stations, or to understand the impact of various factors on consumption.

The motorist is asked:

- What is the consumption of your car?

- Yes, no more than 5-6 liters per hundred.

A little bit later:

- Take me to one place. Nearby is 100 km. I'll give you gas. How many liters do you need?

- OOO! Yes, it's 10 liters, at least.

— …

Formula and principles for calculating fuel consumption

If we discard the secondary factors that affect consumption, then to calculate it, you need to know only two indicators - mileage, and the amount of fuel spent on it. With car mileage, everything is simple. Any model has an odometer for both daily mileage and total mileage. With the help of these devices, fixing the mileage is not a problem. But here there are a couple of nuances.

Firstly, the regular odometer does not always show the distance traveled corresponding to reality. For example, if non-standard wheels or tires are installed on the machine. This all changes the circumference of the wheels, and therefore the readings can be both overestimated and underestimated. Moreover, even the pressure in the tires depends on how far the wheel travels in one revolution.

Secondly, it is practically useless to try to calculate fuel consumption, focusing on the readings of navigation instruments. They mark the kilometers traveled extremely inaccurately. What can I say, if even during parking, many navigators continue to add mileage. Of course, you can roughly find out the flow rate in both the first and second cases. But the accuracy will be such that it is easier to look at the technical characteristics of the car, and not waste your time.

However, calculating mileage is much easier than calculating fuel burned. In fact, this is precisely the difference between the methods described below. So we will return to this issue a little later. Now let's figure out how to calculate fuel consumption based on the kilometers traveled and the liters spent.


R = (V / L) × 100

Or like this:

R = V ×100/ L

Where R is fuel consumption per 100 km;

V is the fuel spent during measurements in liters;

L - marked mileage;

100 is a coefficient due to which the result is obtained in liters per 100 km.

If you need to calculate fuel consumption per 1 km of track, then it is enough to remove the coefficient from the formula. As a result, we get net l / km. This allows using the same formula to find out the cost of a kilometer in money. To do this, we multiply the amount of fuel spent per 1 kilometer by the price of 1 liter at a gas station.

For clarity, let's look at a couple of examples with specific numbers. Suppose the car traveled exactly 100 km, spending 9 liters of gasoline on this path. We substitute the numbers in one of the formulas, and we get the flow rate - 9 liters per hundred. Same with other miles. For example, the mileage was 600 km, and 50 liters of fuel were spent. We substitute the values in the formula and get the flow rate - 8.33 liters per 100 km.

Having such results, it will be easy to calculate the fuel consumption per 1 km. In the first example, this is 900 ml or 0.9 liters. In the second, respectively, 833 ml or 0.83 liters. If the price of a liter is, say, $1, a kilometer of travel in our examples will cost 90 and 83 cents. Now even a child will be able to tell how much money will have to be spent on refueling, if the distance to the destination is known.

Accuracy of fuel consumption calculation

Before you calculate the fuel consumption of your car, it is extremely important to be familiar with the factors that affect accuracy. Otherwise, you can mislead yourself. For example, it is unfair to attribute a diagnosis to a car - it eats buckets. Or get very optimistic results, and then, in fact, go at a loss, using the machine to make money. Perhaps many of these factors will seem obvious, and therefore unworthy of mention. But let's not forget about novice motorists who have recently begun to get acquainted with such an exciting business as owning a car.

Factors affecting the calculation of fuel consumption:

  1. Very often, when the car owner is focused on measurements, he tries to drive a car in a style unusual for him. Not so aggressive on the accelerator pedal, read about how to shift gears, and does it differently. As a result, the consumption is underestimated, not corresponding to the average.
  2. If you want to calculate your gas mileage as accurately as possible, increase your miles. The longer the distance traveled, the more the indicators are averaged, and the result approaches reality.
  3. Surely everyone knows that the consumption is different in the city and on the highway. Therefore, if you want to know some kind of average, divide the measured period into two parts by driving them in different modes.
  4. Road condition. You should not choose an area with perfect coverage for measurements. The figures obtained will be very far from reality, since the pits significantly affect fuel consumption.
  5. In summer, on average, there is less fuel per hundred than in winter. Including, this affects the warming up of the engine.
  6. Current weather. In one way or another, fuel consumption is affected by the direction of the wind, and its speed, and density. Precipitation, temperature and humidity are also taken into account.
  7. The quality of gasoline (diesel). If you stock up on high-quality gasoline for the time of measurement, but usually refuel with something cheaper and with a different octane number, the indicators can vary very noticeably.
  8. Machine loading. It is believed that every additional 100 kg of cargo carried results in a 10% increase in consumption. This is a very inaccurate figure, but it is not without meaning.
  9. Tire pressure. The larger it is, the less fuel is consumed. Not by much, but in combination with other factors, a solid error accumulates.
  10. Included consumers. Especially for powerful devices - headlights, air conditioning, defrosters and other things. All this gives a noticeable load on the generator, which is pulled by the motor.

From all this it follows that it is not so easy to calculate fuel consumption correctly. On the one hand, there are ways to find out everything in half an hour. But in this case, many factors that give errors during the year cannot be taken into account. On the other hand, there are methods designed for long-term use. Yes, this approach is slow. But only it gives truly accurate, objective, honest results.

Quick Ways to Calculate Fuel Consumption

Despite what has just been said, quick methods for calculating the fuel consumption of a car are, nevertheless, necessary. Firstly, not everyone has the desire and time to focus on this for several months in a row. Secondly, the fast method can be applied several times, constantly changing conditions. For example, calculate fuel consumption in winter, and the second time in summer. Then separately on the highway and in the city. As a result, it will be possible to collect different, but quite specific indicators. And some of them are average.

Actually, there are two quick ways, and both of them involve filling the car's tank to full. Perhaps this condition is another drawback. Agree, not every motorist is ready to fill a full tank just to find out the fuel consumption. Especially if he started it for the sake of satisfying a sporting interest. Many regularly travel, as they say, "on a light bulb." Therefore, if you are one of them, immediately proceed to slow methods.

Quick way 1

It is good not only because for some half an hour it allows you to find out the fuel consumption. It is almost the only one if your car runs on gas. All happy owners of HBO know that there are some difficulties with controlling the consumption of this type of fuel. Let's get started.

Full tank of gasoline
Full tank of gasoline

Action algorithm:

  1. We're going to the gas station.
  2. Fill up to full.
  3. Note the mileage.
  4. We drive (the more, the more objective the results will be).
  5. We return to the gas station.
  6. We mark the run.
  7. We refuel again to full.
  8. We look at the column - how many liters are included.
  9. We get two treasured figures - liters and kilometers.
  10. We substitute them into one of the above formulas.

Regarding this method, it is worth noting a couple of characteristic nuances. First, try to return after measurements to the same gas station where you filled the full tank at the beginning. No one has canceled the underfill yet. Secondly, the accuracy of this method increases in direct proportion to its cost. That is, the more control kilometers you drive, you will burn more fuel. But the result will be more accurate. By the way, no one forces you to do a control run to no avail. You can return to the gas station on the second day.

Fast way 2

This method is similar in principle to the previous one. But it has a couple of significant advantages. We will return to them later, but for now we will prepare a little. Actually, in order to calculate fuel consumption in this way, you will need some kind of container with the ability to accurately measure the displacement. Many take a plastic canister, on the side of which there is a gradation in liters. It is better to refuse such an option.

Firstly, it is unsafe to collect fuel in plastic containers. And not all gas stations will allow it to be used. Therefore, we take a normal steel canister designed for gasoline. Separately, we stock up on some kind of measuring vessel, with which it will be possible to measure the volume with high accuracy. Sold at any hardware store.

Canisters for gasoline
Canisters for gasoline

Action algorithm:

  1. We go to the gas station.
  2. We mark the mileage (reset the daily or write down the total).
  3. Fill up a full tank.
  4. Additionally, we collect fuel in the canister.
  5. We drive as much as we took with us gasoline in a canister.
  6. Record the distance travelled.
  7. We compensate for the burned fuel from the canister, measuring the volume along the way.
  8. How much went into the tank, so much was spent on the distance traveled.
  9. Now we have all the necessary data.
  10. We substitute them into the universal formula and find out the consumption.

Now a few words about the benefits mentioned above. The first advantage of the described method of calculating fuel consumption is that you do not have to visit a gas station after measurements. In some cases, this is actually out of hand. The second advantage is that you eliminate the error in case of underfilling at a gas station. That is, if in the previous method you find out the amount of compensated fuel from the scoreboard on the column (and air is often counted there), then in the second - what you yourself intended will be.

Slow Ways to Calculate Fuel Consumption

There are three of these here. All proven in practice. Everyone has a common drawback - it will not work quickly to calculate fuel consumption. But any of them ultimately gives exactly the average, taking into account all the factors that affect accuracy. Let's get started.

Slow way 1

All he needs is a smartphone. You need to install one of the many applications that are designed to track fuel consumption on it. They are both free and paid. In fact, buying an application with additional functionality does not make much sense. Moreover, even free options can not only calculate gas mileage, but also have other interesting features.

It is very easy to work with such applications. Open, create a profile for your car. And then, at each refueling, enter the current mileage on the total odometer, filled liters and money spent into the appropriate forms. The more fillings you make, the more accurate and objective the results will be. As a rule, they are expressed both in understandable figures, and in graphs, and in tables. Additionally, other interesting statistics are shown.

Mobile application for car owner
Mobile application for car owner

There are only a couple of drawbacks. First, you must not forget to enter each gas station, otherwise, you understand, the program will calculate the fuel consumption incorrectly. The second drawback is that you won’t be able to learn anything in one day. At a minimum, it is necessary to naturally refuel at least three times. Ideally, enter data for several months. At the same time, you can clearly see the dynamics of fuel consumption. The difference between the winter and summer charts looks especially good.

Slow way 2

The principle of operation of this method is the same as the previous one. Only in this case, it will not be the program that will calculate the fuel consumption, but you. Using the formula. All you have to do is try to refuel using the arrow method. It lies in the fact that you visit a gas station when the fuel level in the tank drops to approximately the same mark. For example, when the arrow on the instrument panel enters the red zone.

Refueled. Recorded in a notebook the amount of fuel filled and the odometer reading. Everything. After several such gas stations, you will accumulate a certain mileage and the amount of fuel spent. Insert the numbers into our formula and find out the expense. Again, the more fillings will be recorded, the more honest the result will be. Although, by and large, after 3-5 visits to the gas station, according to the described principle, you can get sane indicators.

Slow way 3

Fuel level lamp
Fuel level lamp

Similar to the previous method, only suitable for those who have a low fuel light on the instrument panel. That is, in this case, we try to go to the gas station as soon as the light comes on. Each time the mileage and the amount of fuel filled are noted. As a result, the data necessary for calculating the consumption will be accumulated in the notebook. Unlike the arrow method, the light bulb is a more accurate guide. Or rather, accelerating the receipt of an adequate result. To get it, it is not at all necessary to refuel exactly according to the light bulb or arrow. But if you do it this way, you can calculate fuel consumption earlier.

Brief summary

As a result, we examined in detail as many as 5 ways to calculate fuel consumption. Two of them are fast, but not very objective. Three, on the contrary, are slow. But on the other hand, they help to include errors in the data obtained, which, as you yourself saw, are not so small. If you ignore them, then it is impossible to calculate fuel consumption and get honest results. They are bound to be either too high or too low.

VIDEO: about fuel consumption