Fuel Consumption Calculator
Enter kVA or kW to see diesel use per hour at ¼, ½, ¾ and full load, plus tank runtime. Typical: 100 kVA ≈ 16 L/h at 75% load, about 21 L/h at full load.
Enter your generator’s power to estimate its approximate hourly diesel consumption at different load levels. Below the calculator is a typical consumption table by kVA, taken from our product data.
Estimated full-load consumption is calculated with the formula active power (kW) × 0.28 litres/hour; when you enter kVA, active power is found as kW = kVA × power factor. Results are approximate: actual consumption varies with engine make and model, maintenance condition, ambient temperature and the nature of the load. Model-specific values are given in the technical tables on the product pages.
With the formula, 100 kVA (power factor 0.8 → 80 kW) gives 80 × 0.28 = 22.4 L/h at full load and 16.8 L/h at 75% load; this is what the calculator shows when it opens. The 16 and 21 L/h in the typical consumption table and in the worked example are the median of the same power group in our product data. Because the two methods differ, the results can differ by a few litres.
Load and consumption
A diesel generator’s fuel consumption rises with the load it carries. Generators used for standby power usually run between 50% and 75% load, so the 75% load value is commonly used for cost and tank calculations. The full-load (100%) value is used for worst-case tank and refuelling planning.
Worked example
Assume a 100 kVA generator will run on a construction site for 10 hours a day at an average load of 75%:
- Hourly consumption: In the typical consumption table below the calculator, the 100 kVA row shows a typical value of about 16 litres per hour at 75% load.
- Daily consumption: 16 L/h × 10 h = about 160 litres.
- Weekly consumption (6 days): 160 L × 6 = about 960 litres.
- Tank running time: With a 200-litre tank, 200 ÷ 16 = about 12.5 hours of running; with a 10% reserve, about 11 hours.
If the same generator runs at full load, hourly consumption rises to about 21 litres and the tank running time is shorter. For a project-specific calculation, use the value on the product page of the selected model.
Related pages
- Details of the formula: how to calculate generator fuel consumption
- Tank volume and running time: generator fuel tank sizing
- To find the power you need: power calculator
- All models and technical data: products
Typical fuel consumption by kVA
Typical values: the median consumption calculated from the product data of the diesel generator models on our site. Each row covers a power group; unverified fields are excluded. For model-specific values, see the technical table on the product page.
| Rating | Standby ratings covered (kVA) | At 50% load (L/h, typical) | At 75% load (L/h, typical) | At 100% load (L/h, typical) |
|---|---|---|---|---|
| 20 kVA | 16–24 | 2.9 | 4 | 5.3 |
| 30 kVA | 25–38 | 3.9 | 5.4 | 6.6 |
| 50 kVA | 40–60 | 5.7 | 8.2 | 10.7 |
| 75 kVA | 61–89 | 8.1 | 11.5 | 15 |
| 100 kVA | 90–124 | 10.6 | 16 | 21.3 |
| 150 kVA | 125–174 | 15.9 | 23 | 30.3 |
| 200 kVA | 175–229 | 19.5 | 32 | 41.4 |
| 250 kVA | 230–300 | 27.3 | 41.2 | 56 |
| 400 kVA | 301–439 | 35.8 | 52.3 | 69.7 |
| 500 kVA | 440–560 | 47 | 71 | 95 |
| 650 kVA | 561–700 | 60.9 | 90 | 122.3 |
| 800 kVA | 701–899 | 74.4 | 111.7 | 149.5 |
| 1000 kVA | 900–1120 | 100.8 | 146.5 | 195.5 |
| 1250 kVA | 1121–1400 | 133.1 | 193.4 | 258 |
| 1500 kVA | 1401–1700 | 155 | 222 | 296.9 |
| 2000 kVA | 1701–2250 | 200 | 291 | 401 |
| 2500 kVA | 2251–2800 | 240.5 | 355 | 484.7 |
| 3000 kVA | 2801–3400 | 311.1 | 450.4 | 586.7 |
| 4000 kVA | 3401–4125 | 364.9 | 526 | 707.8 |
Frequently asked questions
How many litres per hour does a 100 kVA generator use?
In the 100 kVA power group in our product data, typical consumption at 75% load is about 16 litres per hour, rising to about 21 litres at full load. The actual value depends on the engine make and model, the load and the maintenance condition; the model-specific value is given in the technical table on the product page.
What affects fuel consumption most?
The biggest factor is the load: the more the generator is loaded, the more fuel it uses. Engine make and model, maintenance condition (air and fuel filters, injectors), fuel quality, ambient temperature and altitude also affect consumption.
Does running a generator at low load save fuel?
Hourly consumption falls, but consumption per kWh produced rises. Diesel engines that run at very low load for long periods do not burn fuel completely, and soot builds up in the exhaust. For this reason the generator's power should match the requirement; you can use the power calculator to find the right size.
How many hours will a fuel tank last?
Divide the tank volume (litres) by the hourly consumption at the expected load to find the approximate running time. For example, with a 200-litre tank and consumption of 16 litres per hour, the running time is about 12.5 hours. To avoid running the tank completely dry, it is advisable to keep a reserve of about 10% in the calculation.
Why do the typical values in the table differ from model-specific values?
The table shows the median value of models built with different engine makes in the same power group. Within a group there are differences by engine make and standby rating; for quotations and project calculations, use the model-specific value on the product page.