Energy density converter
Convert the energy packed into each kilogram of a fuel or a battery, in MJ/kg, kWh/kg, kcal/kg or BTU/lb.
That's about the same as petrol. To match a 60 kWh car battery you would need about 4.696 kg of it.
What it means
How much energy per kilogram?
Figures are the higher heating value by mass. They ignore the weight of the tank, engine or fuel cell around them.
Every unit
Your energy density in every unit
Learn
Three things worth knowing
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1 kWh/kg is 3.6 MJ/kg
Batteries are quoted in Wh/kg, fuels in MJ/kg. Multiply Wh/kg by 3.6 to get kJ/kg and the comparison becomes fair.
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Why hydrogen flatters itself
Hydrogen leads on energy per kilogram at 120 MJ/kg, but it is so light that a tank of it is bulky. By volume it loses badly to diesel.
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Per kilogram or per liter?
Fuel tanks have a size as well as a weight. Energy per liter decides the tank, energy per kilogram decides the payload.
Shortcuts
Popular energy density conversions
Background
About energy density
Energy density says how much energy each kilogram holds. It is the single number that explains why aircraft burn kerosene: petrol holds 46 MJ/kg while a lithium battery manages 0.9.