From SFOC to t/day
kg/h = SFOC x P / 1000 = 190 x 3000 / 1000 = 570 kg/h (190 g/kWh is an example). t/day = 570 x 24 / 1000 = 13.68 t/day. At 85 % of 5000 kW the power is P = 4250 kW.
Reference tool — arithmetic, not engine data
Fuel consumption.
SFOC · kg/h · t/day · m3/day · endurance
SFOC, power, days.
Type a line (SFOC 190 g/kWh 3000 kW; 185 g/kWh 85 % of 5000 kW density 0.89; consumed 12.5 t in 24 h at 2800 kW; add tank 350 m3 for the days) or fill in the fields: the line and the fields stay in step.
Examples:
All 130 engineering tools
Enter the SFOC of a diesel engine or a generator set from its shop test and the power, in kW, MW, hp or PS or as a per cent load of the rated power, and the calculator gives the fuel consumption in kg/h, t/h and t/day; with the density at 15 °C it adds m3/h, m3/day and l/h. It also works the other way, the SFOC from a measured consumption (a flow meter, or tank soundings over a time) and the power, and gives the endurance: the days the fuel on board lasts. The working is shown with your numbers, a bar draws the fuel on board against one day of consumption to scale, and the result is a line you can copy.
Arithmetic only: no typical SFOC, no density correction for temperature (the ASTM D1250 volume correction factors are not applied), no emission factors and no fuel prices. The engine maker data govern.
How it is worked out
Mass, volume, days.
From tonnes to m3
m3/h = kg/h / density = 570 / 890 = 0.6404 m3/h = 640.4 l/h; x 24 = 15.37 m3/day. The density at 15 °C is the one on the bunker delivery note; no correction for temperature.
Back to the SFOC, and days on board
SFOC = kg/h x 1000 / P: 12.5 t in 24 h at 2800 kW is 520.83 x 1000 / 2800 = 186.01 g/kWh. Days = fuel on board / consumption per day: 350 m3 / 15.37 m3/day = 22.77 days.
| g/kWh | g/hph | g/PSh | kg/h per 1000 kW | t/day per 1000 kW |
|---|---|---|---|---|
| 150 | 111.9 | 110.3 | 150 | 3.60 |
| 175 | 130.5 | 128.7 | 175 | 4.20 |
| 200 | 149.1 | 147.1 | 200 | 4.80 |
| 225 | 167.8 | 165.5 | 225 | 5.40 |
| 250 | 186.4 | 183.9 | 250 | 6.00 |
The figures in the first column are round numbers for the conversion, not typical SFOC values: the shop test gives the SFOC of your engine. 1 g/hph = 1.34102 g/kWh, 1 g/PSh = 1.35962 g/kWh.
Sources
The consumption is plain arithmetic: kg/h = SFOC x P / 1000, t/day = kg/h x 24 / 1000, m3 = mass / density, and the reverse. That shop-test SFOC is quoted at the ISO 3046-1 reference conditions and for a fuel of a stated lower calorific value (42 700 kJ/kg), with a tolerance, is stated alike in the published engine definitions of two engine makers and in a two-stroke engine project guide. The DMA density pick is the upper limit in table 1 of ISO 8217, editions 2010 and 2017, as two fuel references reproduce it. 1 hp = 745.69987 W (550 ft lbf/s) and 1 PS = 735.49875 W (75 kgf m/s) are exact by definition. The engine maker data and the bunker delivery note always come first.
Before you work it out
Questions about fuel consumption
How is the fuel consumption worked out from the SFOC?
The consumption in kg/h is the SFOC in g/kWh times the power in kW, divided by 1000. An engine at 3000 kW with an SFOC of 190 g/kWh (an example figure, not a typical one) burns 190 x 3000 / 1000 = 570 kg/h, and 570 x 24 / 1000 = 13.68 t/day. At a part load the power is that per cent of the rated power: 85 % of 5000 kW is 4250 kW, and at an SFOC of 185 g/kWh that is 786.25 kg/h, 18.87 t/day.
How do I get m3 and litres?
Divide the mass by the density: 570 kg/h at 890 kg/m3 is 0.6404 m3/h, 640.4 l/h and 15.37 m3/day. Take the density at 15 °C from the bunker delivery note, in kg/m3 or kg/l (0.89 kg/l is 890 kg/m3). The one density offered as a pick is the ISO 8217 upper limit for DMA, 890 kg/m3 at 15 °C, which is a limit and not the density of a delivery; there is no pick for residual fuels. No correction is made for temperature: the ASTM D1250 volume correction factors are not included.
Where does the SFOC come from, and under which conditions is it quoted?
From the shop test report or the engine maker data, at the load you work with; this page gives no typical SFOC. Engine makers quote it at the ISO 3046-1 reference conditions (air at 25 °C and 1 bar) and for a fuel of a stated lower calorific value, 42 700 kJ/kg in the maker data checked for this page, with a tolerance. For service figures, the engine maker data govern.
How is the SFOC worked out from a measured consumption?
Divide the mass consumed per hour by the power: 12.5 t in 24 h is 520.83 kg/h, and at 2800 kW that is 520.83 x 1000 / 2800 = 186.01 g/kWh. A flow meter or tank soundings in m3 need the density first: from 48.6 to 44.4 m3 in 12 h is 0.35 m3/h, at 860 kg/m3 that is 301 kg/h, and at 1500 kW 200.67 g/kWh. The power must be the one the engine delivered over the same time.
How many days does the fuel on board last?
The quantity divided by the consumption per day, both in tonnes or both in m3: 350 m3 at 15.37 m3/day lasts 22.77 days, 546.5 h. If the tank is in m3 and the consumption in tonnes, the density links them. The whole quantity entered is used: no unpumpable remainder and no reserve are taken off.
Which units does the calculator take?
The SFOC in g/kWh, g/hph (mechanical horsepower, 745.69987 W) or g/PSh (metric horsepower, 735.49875 W), so 1 g/hph = 1.34102 g/kWh and 1 g/PSh = 1.35962 g/kWh. The power in kW, MW, hp or PS; kWe is read as kW, so take the SFOC and the power on the same basis. A measured consumption in kg/h, t/h, t/day, m3/h, m3/day, l/h or l/min, or a quantity in t, kg, m3 or l over a time in h, days or min. There are no emission factors and no fuel costs.
Parts for the engine or its fuel system?
Send the engine type and the part.
The calculator works out the consumption from the figures you enter. When fuel pumps, injectors, filters or other parts for the engine are needed, send the engine type, its serial number and a photograph of the nameplate, and Vessel Core checks the details before an offer goes back.
Buyer tools
