Table of contents
- Introduction
- Diesel Generator Fuel Consumption Chart (kVA → L/hr) at 25/50/75/100% Load
- How to Calculate Diesel Generator Fuel Consumption (L/hr & L/kWh)
- Diesel generator fuel consumption formula (L/hr and L/kWh)
- Need an instant result? Try our Fuel Consumption Calculator →
- What Affects Fuel Consumption?
- What Load Uses the Least Fuel? (The 50–80% Efficiency Sweet Spot)
- How many liters per hour does a 100 kVA diesel generator use?
- Fuel Use by Duration (Example: 100 kVA at Full Load)
- Conclusion
Introduction
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A clear fuel consumption chart by kVA, kW and load percentage.
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Practical real-world examples (construction site, home backup, hospitals).
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A free online calculator for personalized results.
Diesel Generator Fuel Consumption Chart (kVA → L/hr) at 25/50/75/100% Load
| Generator Size (kVA) | 50% Load (L/h) | 75% Load (L/h) | 100% Load (L/h) |
|---|---|---|---|
| 20 kVA | 2.5 L | 3.7 L | 5.0 L |
| 50 kVA | 5.5 L | 8.0 L | 11.0 L |
| 100 kVA | 11.0 L | 16.0 L | 22.0 L |
| 200 kVA | 20.0 L | 30.0 L | 40.0 L |
| 500 kVA | 55.0 L | 82.0 L | 110.0 L |
💡Tip: Running a generator at 50–75% load is often more fuel-efficient than at full load.For a quick and accurate estimate tailored to your generator, try our Diesel Generator Fuel Consumption Calculator – Free Online Tool.
How to Calculate Diesel Generator Fuel Consumption (L/hr & L/kWh)
- 100 kVA generator, ~75% load, 10 hours/day
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≈ 16 L/h × 10 h = 160 L/day
- 30 kVA generator, 5 hours, full load
- ≈ 6.6 L/h × 5 h = 33 L
- 500 kVA generator, 24h/day, full load
- ≈ 110 L/h × 24 h = 2,640 L/day
Diesel generator fuel consumption formula (L/hr and L/kWh)
1) Formula: convert power load to fuel use per hour (L/hr)
Fuel consumption (L/hr) = Electrical output (kW) × Specific fuel consumption (L/kWh)
- kW = real power your generator is delivering (important: not kVA)
- L/kWh = liters of diesel needed to produce 1 kWh
- Typical diesel genset at mid-load might be around 0.24–0.30 L/kWh (varies by model and load)
2) Convert kVA to kW (if you only know kVA)
kW = kVA × Power Factor (PF)
Where:
•PF is often 0.8 for many industrial loads (but your real PF could be 0.7–1.0)
3) One worked example (100 kVA at 75% load)
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Assume:
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Generator size = 100 kVA
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Load level = 75%
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Power factor (PF) = 0.8
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SFC = 0.27 L/kWh (example value)
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Step 1) Convert 75% load to kVA output
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kVA output = 100 × 0.75 = 75 kVA
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Step 2) Convert kVA to kW
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kW = 75 × 0.8 = 60 kW
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Step 3) Convert kW to L/hr
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L/hr = 60 × 0.27 = 16.2 L/hr
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4) Optional: cost per hour
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Fuel cost per hour = L/hr × diesel price per liter
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For example: 16.2 L/hr × $1.20/L = $19.44 per hour
Need an instant result? Try our Fuel Consumption Calculator →
What Affects Fuel Consumption?
- Load level – 50%, 75%, or 100% of generator capacity.
- Generator size & efficiency – newer models may save fuel.
- Maintenance & condition – dirty filters = more fuel.
- Operating environment – hot climates and high altitudes reduce efficiency.
What Load Uses the Least Fuel? (The 50–80% Efficiency Sweet Spot)
- Most diesel generators are most fuel-efficient at ~50–80% load (best balance of fuel use, combustion efficiency, and engine temperature).
- Below ~30–40% load, fuel economy usually worsens because the engine still burns “baseline” fuel and may run cooler/less efficiently (light-load operation).
- At ~90–100% load, total fuel use is highest and heat stress increases—it can be efficient per kWh for short periods, but it’s not the best “everyday” operating point for economy and longevity.
How many liters per hour does a 100 kVA diesel generator use?
Quick answer (typical diesel genset): a 100 kVA generator usually burns the least fuel per kWh around 50–80% load, and the liters per hour (L/hr) depends mainly on load % and engine efficiency.
Typical fuel consumption for a 100 kVA diesel generator (L/hr)
- At 50% load (~50 kVA): ~10–14 L/hr
- At 75% load (~75 kVA): ~14–20 L/hr
- At 100% load (~100 kVA): ~18–26 L/hr
*Rule of thumb range (real-world varies by engine brand, altitude, temperature, maintenance, and fuel quality).
Why the range is wide (what changes L/hr)
- Engine & alternator efficiency: premium engines often consume less fuel at the same load.
- Load type: motors / compressors (high reactive power & surges) can raise consumption.
- Operating conditions: high altitude / high heat reduces power and may increase L/hr.
- Maintenance: clogged filters, injector wear, low-quality diesel increase fuel use.
Fuel Use by Duration (Example: 100 kVA at Full Load)
| Duration of Use | Fuel Consumption |
|---|---|
| 1 hour | 22 L |
| 8 hours | 176 L |
| 24 hours | 528 L |
| 7 days | 3,696 L |
Conclusion
- Use the chart for quick estimation
- Review the real-world examples for practical insight
- Try the free tool for accurate, personalized results
- 🚀 Calculate My Generator Fuel Consumption Now
