Generator Fuel Consumption Calculator
Fuel burn per hour and tank runtime from load and specific fuel consumption. With the formula, a worked example and typical values.
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Estimate only. Not engineering or safety advice. Check the result against the applicable standard and the equipment data, and have a competent engineer review it before it is relied on. Terms of use.
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About this calculator
This page calculates fuel consumption and runtime on one tank from electrical load, specific fuel consumption, fuel density and tank volume. Change any value or its unit and the result updates. The steps below show the working for the default values, so you can check each line against your own method.
Limits of this calculator
Assume no more than about 90% of the tank is usable, and add reserve for fuel-polishing and sludge.
Cross-check: 6 reference cases, calculated from textbook formulas coded separately from the engine by the same author, agree with this calculator. This is not an independent review.
Verification status: Indicative
Indicative. Estimation only; further engineering checks are required. Basis: Fuel-consumption estimate.
What this calculator checks
- The arithmetic of the simplified model for the values you entered.
What remains unverified
- Whether the simplifying assumptions listed on this page hold for your case.
- Any standard, manufacturer or site data. Treat the result as an estimate and confirm it by a further engineering check.
Verification register entry
| Calculation author | Rahul Sharma (author) |
|---|---|
| Technical review | No independent technical review has been carried out |
| Individual professional approval | Not recorded |
| Formula reference | not recorded |
| Standard and edition | Not applicable: Fuel use is based on manufacturer-specific SFC and fuel density. No universal standard fixes the consumption value or this calculator’s simplified autonomy equation. |
| Standard review state | Not applicable |
| Scope-screening note | not recorded |
| Cross-check test cases | 6 reference vectors (tests/reference_vectors.json) |
| Review date | not recorded |
| Next review date | not recorded |
| Status | Indicative |
Needed before this calculator can be marked Verified: reviewer name, qualification and review date; exact formula reference; formula source (textbook or standard); next review date.
Formula
Worked example
| Input | Value |
|---|---|
| Electrical load | 400 kW |
| Specific fuel consumption (g/kWh) | 230 |
| Fuel density (kg/L) | 0.84 |
| Tank volume | 500 L |
- Fuel = 400 kW × 230 g/kWh = 92 kg/h
- L/h = 92 / 0.84 = 109.52 L/h
- Runtime = 500 L / 109.52 = 4.57 h
Assumptions
- Steady load
- SFC taken at the stated load
Assume no more than about 90% of the tank is usable, and add reserve for fuel-polishing and sludge.
Inputs and results
| Input | Unit | Allowed or shown | Note |
|---|---|---|---|
| Electrical load | kW | greater than 0 kW | |
| Specific fuel consumption (g/kWh) | (number) | 100 or more, up to 600 | From the engine data sheet at this load, typically 200 to 260 for diesel |
| Fuel density (kg/L) | (number) | 0.5 or more, up to 1.2 | |
| Tank volume | L | greater than 0 L |
| Result | Unit | Allowed or shown | Note |
|---|---|---|---|
| Fuel consumption (L/h) | (number) | Shown to 1 decimal place | |
| Runtime on one tank | h | Shown to 2 decimal places |
How it is calculated
Each input is converted to the base unit of its quantity, the formula above is applied in the order shown in the worked example, and each result is shown in the unit you choose. Results are held at full precision and rounded only for display, except where a step selects a standard size, as the worked example shows. A value outside its allowed range is refused with a message instead of giving a result.
How the result changes with electrical load
| Electrical load (kW) | Fuel consumption | Runtime on one tank (h) |
|---|---|---|
| 40 | 11 | 45.65 |
| 100 | 27.4 | 18.26 |
| 200 | 54.8 | 9.13 |
| 400 | 109.5 | 4.57 |
| 800 | 219 | 2.28 |
| 1,600 | 438.1 | 1.14 |
| 4,000 | 1,095.2 | 0.46 |
Other inputs are the same as in the worked example above.
Standards and further reading
- IEC 60909-0 (short-circuit currents)
- IEEE Std 519 (harmonic limits)
Check results against your utility's connection requirements and the equipment data sheets. These are named as background reading. Elecmetric does not embed clause text or rating tables, and the reviewer record for this calculator is separate from this list.
Frequently asked questions
What do I need to enter?
Enter electrical load, specific fuel consumption (g/kWh), fuel density (kg/L) and tank volume. Change the unit of a value with its selector and the result stays the same.
What does this calculator assume?
Steady load. SFC taken at the stated load.
Which calculators should I use next?
Common next steps are Generator kVA Selection and Appliance Running Cost (Energy and Cost). The related links at the bottom of this page open them.
How accurate are the results?
Every figure comes from the same tested engine as the Elecmetric calculators and is meant for estimating. 6 reference cases, calculated from textbook formulas coded separately from the engine by the same author, agree with this calculator. This is not an independent review. Check design values against the standard and the equipment data you work to.
Formula guides and reference
Longer explanations with worked examples and tables, written for the same topic.
- Generator Formulas: kVA, Current and Fuel: Generator formulas for kVA from kW and power factor, rated current, fuel use from specific consumption and tank runtime
- Generator Droop and Load Sharing Formulas: Generator droop formulas: the droop percentage, the load from the frequency and the load shared by parallel generators…
- Load Bank Test Formulas: Load bank test formulas for a generator: the rated power, the test steps
More Power Systems calculatorsAll engineering calculatorsGenerator Fuel Consumption and Autonomy in Elecmetric