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Fuel Efficiency-Mass Converter

Convert J/kg, cal/g, BTU/lb, kg/J, and more — instantly.

Free fuel efficiency (mass) converter. Convert joules per kilogram to calorie and BTU variants; mass-per-energy units use verified inverse math. Use the express converter for any unit pair, or open a quick conversion below.

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1 joule per kilogram = 0.0004299226 BTU (IT) per pound

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Hand-picked pairs with dedicated converter pages — open one to convert instantly.

Joule per Kilogram → Kilojoule per Kilogram

Joule per Kilogram to Kilojoule per Kilogram

Kilojoule per Kilogram → Joule per Kilogram

Kilojoule per Kilogram to Joule per Kilogram

Joule per Kilogram → BTU (IT) per Pound

Joule per Kilogram to BTU (IT) per Pound

BTU (IT) per Pound → Joule per Kilogram

BTU (IT) per Pound to Joule per Kilogram

Calorie (IT) per Gram → Joule per Kilogram

Calorie (IT) per Gram to Joule per Kilogram

Joule per Kilogram → Calorie (IT) per Gram

Joule per Kilogram to Calorie (IT) per Gram

Browse all fuel efficiency (mass) units

Pick any unit to open a two-way conversion. IT and thermochemical calories/BTUs are labeled separately. Mass-per-energy reciprocal units use inverse math.

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JOULE PER KILOGRAM

1 J/kg = 0.0004299226 BTU (IT)/lb

joule per kilogram (J/kg) → btu (it) per pound (BTU (IT)/lb) btu (it) per pound (BTU (IT)/lb) → joule per kilogram (J/kg)

KILOJOULE PER KILOGRAM

1 kJ/kg = 1,000 J/kg

kilojoule per kilogram (kJ/kg) → joule per kilogram (J/kg) joule per kilogram (J/kg) → kilojoule per kilogram (kJ/kg)

CALORIE (IT) PER GRAM

1 cal (IT)/g = 4,186.8 J/kg

calorie (it) per gram (cal (IT)/g) → joule per kilogram (J/kg) joule per kilogram (J/kg) → calorie (it) per gram (cal (IT)/g)

CALORIE (THERMOCHEMICAL) PER GRAM

1 cal (th)/g = 4,184 J/kg

calorie (thermochemical) per gram (cal (th)/g) → joule per kilogram (J/kg) joule per kilogram (J/kg) → calorie (thermochemical) per gram (cal (th)/g)

BTU (IT) PER POUND

1 BTU (IT)/lb = 2,326 J/kg

btu (it) per pound (BTU (IT)/lb) → joule per kilogram (J/kg) joule per kilogram (J/kg) → btu (it) per pound (BTU (IT)/lb)

BTU (THERMOCHEMICAL) PER POUND

1 BTU (th)/lb = 2,324.4 J/kg

btu (thermochemical) per pound (BTU (th)/lb) → joule per kilogram (J/kg) joule per kilogram (J/kg) → btu (thermochemical) per pound (BTU (th)/lb)

KILOGRAM PER JOULE

1 kg/J = 1 J/kg

kilogram per joule (kg/J) → joule per kilogram (J/kg) joule per kilogram (J/kg) → kilogram per joule (kg/J)

KILOGRAM PER KILOJOULE

1 kg/kJ = 1,000 J/kg

kilogram per kilojoule (kg/kJ) → joule per kilogram (J/kg) joule per kilogram (J/kg) → kilogram per kilojoule (kg/kJ)

GRAM PER CALORIE (IT)

1 g/cal (IT) = 4,186.8 J/kg

gram per calorie (it) (g/cal (IT)) → joule per kilogram (J/kg) joule per kilogram (J/kg) → gram per calorie (it) (g/cal (IT))

GRAM PER CALORIE (THERMOCHEMICAL)

1 g/cal (th) = 4,184 J/kg

gram per calorie (thermochemical) (g/cal (th)) → joule per kilogram (J/kg) joule per kilogram (J/kg) → gram per calorie (thermochemical) (g/cal (th))

POUND PER BTU (IT)

1 lb/BTU (IT) = 2,326 J/kg

pound per btu (it) (lb/BTU (IT)) → joule per kilogram (J/kg) joule per kilogram (J/kg) → pound per btu (it) (lb/BTU (IT))

POUND PER BTU (THERMOCHEMICAL)

1 lb/BTU (th) = 2,324.4 J/kg

pound per btu (thermochemical) (lb/BTU (th)) → joule per kilogram (J/kg) joule per kilogram (J/kg) → pound per btu (thermochemical) (lb/BTU (th))

POUND PER HORSEPOWER HOUR

1 lb/(hp·h) = 5,918,352.5016 J/kg

pound per horsepower hour (lb/(hp·h)) → joule per kilogram (J/kg) joule per kilogram (J/kg) → pound per horsepower hour (lb/(hp·h))

GRAM PER HORSEPOWER (METRIC) HOUR

1 g/(hp (metric)·h) = 2,647,795,500 J/kg

gram per horsepower (metric) hour (g/(hp (metric)·h)) → joule per kilogram (J/kg) joule per kilogram (J/kg) → gram per horsepower (metric) hour (g/(hp (metric)·h))

GRAM PER KILOWATT HOUR

1 g/(kW·h) = 3,600,000,000 J/kg

gram per kilowatt hour (g/(kW·h)) → joule per kilogram (J/kg) joule per kilogram (J/kg) → gram per kilowatt hour (g/(kW·h))