Truck fuel consumption calculator

Calculate the real cost of a trip: diesel, AdBlue and road tolls, with different consumption on the outbound and return legs. The default values are for a 40-ton combination — replace them with your own.

How fuel consumption is calculated

The basic formula is the same for any vehicle:

Liters consumed = (distance in km × consumption per 100 km) ÷ 100

For an 850-kilometer trip with consumption of 31 liters per 100 kilometers, the result is 263.5 liters. Multiply by the diesel purchase price and you get the fuel cost.

The problem arises when this figure is confused with the cost of the trip. For a goods vehicle, diesel is the largest part, but not the only one.

What goes into the real cost per kilometer

The calculator above adds two lines that car calculators don't have:

• AdBlue. Vehicles with an SCR system consume urea solution at a rate of approximately 4–6% of diesel volume. For 263 liters of diesel, that means around 13 liters of AdBlue — a small amount per trip, but a steady one per year and per fleet.
• Road tolls. Entered as an average per kilometer for all countries transited. For vehicles over 3.5 tons, the switch to per-kilometer tolling changes how this cost is calculated — details in the guide on the difference between TollRo and the rovinieta.

What the calculator intentionally leaves out: tires, oil and consumables, servicing and parts, vehicle depreciation, driver wages and per diem, insurance, licenses and certified true copies. These are operating costs that depend not on the trip but on the period, and they are calculated separately — how they are allocated per kilometer is explained in the article on price per kilometer in freight transport.

Why return-leg consumption is different

A combination that runs loaded at 40 tons and returns empty doesn't consume the same in both directions. The difference is typically between 15 and 25%.

Generic calculators use a single consumption figure for the whole distance, which systematically overestimates the cost of a trip with an empty return. Over 1,700 kilometers round trip, the difference between calculating with 31 l/100 km throughout and correctly calculating 31 outbound and 25 on the return exceeds 200 lei — on a single trip.

If the return leg is also loaded, enter the same value in both fields.

What affects consumption, in order of impact

• Payload weight — the factor with the biggest effect, hence the outbound–return difference.
• Route terrain — a mountain route can add a few liters per 100 kilometers compared to the same distance on flat ground.
• Driving style — harsh acceleration and braking, speeds above the fuel-efficient optimum, incorrect use of momentum. The difference between two drivers in the same vehicle on the same route is measurable and often greater than the difference between two truck models.
• Idling — time with the engine running while stationary produces no kilometers but burns fuel. Over a month, accumulated idling hours become a visible cost line.
• Tires and aerodynamics — incorrect pressure, uneven wear, poorly fitted tarps and deflectors.

Estimated vs. measured consumption

The calculator's result is only as accurate as the consumption figure you enter. And that's where the difference between an estimate and a measurement comes in.

The sensitivity table in the calculator shows why it matters: at the default values, just one extra liter per 100 kilometers changes the trip cost by about 90 lei, and over 120 trips a year by around 11,000 lei — for a single vehicle. In a fleet of ten trucks, a one-liter estimation error adds up to an amount well worth looking at.

Real consumption comes from vehicle data, not from the spec sheet. The methods and the differences between them are detailed in the guide on fuel consumption monitoring, and for direct measurement of the tank level, in the article on Fuel level sensor (probe).

Frequently asked questions

How is fuel consumption per 100 km calculated?

Divide the amount of fuel consumed by the distance traveled and multiply by 100. Conversely, to find the liters needed for a trip, multiply the distance by the consumption per 100 km and divide by 100.

How much does a 40-ton truck consume per 100 km?

A tractor unit with a semi-trailer loaded to maximum weight typically consumes between 28 and 34 liters per 100 kilometers, depending on terrain, speed, driving style and vehicle condition. Empty, consumption usually drops by 15–25%.

How much AdBlue does a truck use?

About 4–6% of the diesel volume consumed, for vehicles equipped with an SCR system. For 300 liters of diesel, that's around 15 liters of AdBlue.

What does this calculator not include?

Tires, oil and consumables, servicing and parts, vehicle depreciation, driver wages and per diem, insurance and administrative fees. These are period costs, not trip costs, and are allocated per kilometer separately.

Why does calculated consumption differ from actual consumption?

Because the value you enter is an estimate. Actual consumption varies with payload weight, terrain, driving style, idling time and tire condition. The difference doesn't show on a single trip but in the fleet's monthly average.