Convert Pounds per Btu (IT) to Calories (IT) per Gram
Pound per Btu (IT) (lb/Btu) to Calorie (IT) per Gram (cal/g) mass-basis fuel efficiency conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 lb/Btu = 0.55555556 cal/g
1 Pound per Btu (IT) = 0.55555556 Calories (IT) per Gram
1 Calorie (IT) per Gram = 0.55555556 Pounds per Btu (IT)
1 lb/Btu in every supported unit
Conversion chart: Pound per Btu (IT) to Calories (IT) per Gram
Conversion table
| Pound per Btu (IT) (lb/Btu) | Calorie (IT) per Gram (cal/g) |
|---|---|
| 0.01 lb/Btu | 55.555556 cal/g |
| 0.1 lb/Btu | 5.5555556 cal/g |
| 1 lb/Btu | 0.55555556 cal/g |
| 2 lb/Btu | 0.27777778 cal/g |
| 3 lb/Btu | 0.18518519 cal/g |
| 5 lb/Btu | 0.11111111 cal/g |
| 10 lb/Btu | 0.055555556 cal/g |
| 20 lb/Btu | 0.027777778 cal/g |
| 50 lb/Btu | 0.011111111 cal/g |
| 100 lb/Btu | 0.0055555556 cal/g |
| 1000 lb/Btu | 0.00055555556 cal/g |
Pound per Btu (IT) (lb/Btu)
Definition: A US customary specific fuel consumption unit — pounds of fuel mass required to deliver one British thermal unit of energy, the reciprocal of Btu per pound.
History: A natural inversion of the Btu-per-pound calorific value unit, adopted in US industrial contexts that budget fuel supply by weight against a required heat output.
Current use: Used in US industrial boiler and furnace fuel-supply planning, where the required heat output is known and the fuel mass to be delivered must be calculated.
Calorie (IT) per Gram (cal/g)
Definition: The International Table calorie's specific-energy unit — how many calories of heat energy are released per gram of a substance.
History: Rooted in 19th-century calorimetry, where the calorie was defined as the heat needed to raise one gram of water by one degree Celsius; the International Table calorie was later fixed to a precise joule equivalent for scientific consistency.
Current use: Widely used in nutrition science and food-energy labeling (as kilocalories per gram, i.e. "Calories") and in chemistry for reporting combustion and reaction energies.
Supported Units
| Unit | Symbol | Category |
|---|---|---|
| Joule per Kilogram | J/kg | Specific energy (energy/mass) |
| Kilojoule per Kilogram | kJ/kg | Specific energy (energy/mass) |
| Calorie (IT) per Gram | cal/g | Specific energy (energy/mass) |
| Btu (IT) per Pound | Btu/lb | Specific energy (energy/mass) |
| Kilogram per Kilojoule | kg/kJ | Specific fuel consumption (mass/energy) |
| Gram per Calorie (IT) | g/cal | Specific fuel consumption (mass/energy) |
| Pound per Btu (IT) | lb/Btu | Specific fuel consumption (mass/energy) |
| Pound per Horsepower-hour | lb/(hp·h) | Specific fuel consumption (mass/energy) |
| Gram per Kilowatt-hour | g/kWh | Specific fuel consumption (mass/energy) |
About These Parameters
- Value
- The fuel-efficiency figure you want to convert, expressed in the "From" unit. Accepts decimals.
- From Unit
- The unit your input value is currently measured in — a specific-energy unit like J/kg or Btu/lb, or an engine SFC unit like g/kWh.
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly.
How Fuel Efficiency - Mass Conversion Works
The Formula
Within the same group (both specific energy, or both specific fuel consumption), conversion is a simple multiplication:
result = value × (factor of "From" unit ÷ factor of "To" unit)
Crossing between the two groups instead inverts through the base unit:
SFC unit = (factor of SFC unit) ÷ (value × factor of specific-energy unit)
For Pound per Btu (IT) → Calorie (IT) per Gram: 1 lb/Btu = 0.55555556 cal/g.
Specific Energy vs. Specific Fuel Consumption
Specific energy (J/kg, cal/g, Btu/lb) describes a fuel's raw calorific value — an intrinsic property of the fuel itself, independent of any engine. Specific fuel consumption (g/kWh, lb/(hp·h)) instead describes how efficiently a real engine turns that stored energy into usable mechanical output, and depends on the engine's thermal efficiency, not just the fuel. A lower SFC figure always means a more fuel-efficient engine, the opposite direction from specific energy, where a higher figure means a more energy-dense fuel.
Why g/kWh Replaced lb/(hp·h)
Pounds per horsepower-hour was the standard engine efficiency rating through the early-to-mid 20th century, when horsepower was the universal power unit in aviation and marine engineering. As engine testing and international trade shifted to the metric kilowatt, grams per kilowatt-hour became the global standard — it's the figure printed on virtually every modern diesel and gasoline engine's technical datasheet today.
Example
A diesel engine rated at 200 g/kWh converts to about 0.32879736 lb/(hp·h) — a typical figure for a modern, efficient diesel; older or smaller gasoline engines often run well above 250 g/kWh.
Frequently Asked Questions
How many Calories (IT) per Gram are in 1 Pound per Btu (IT)?
1 Pound per Btu (IT) (lb/Btu) equals exactly 0.55555556 Calories (IT) per Gram (cal/g).
Why does a lower g/kWh mean a better engine, when higher J/kg means a better fuel?
They measure different things in opposite directions. J/kg (specific energy) is a property of the fuel — more energy per kilogram is always better. g/kWh (specific fuel consumption) is a property of the engine — it asks how much fuel mass is spent to deliver one unit of output, so less fuel for the same output means a more efficient engine.
Can I convert a fuel's calorific value directly into an engine's SFC rating?
This converter performs the mathematical reciprocal between the two groups, but that number alone assumes a perfectly (100%) efficient engine. Real engines lose energy to heat, friction, and exhaust, so an actual SFC rating is always numerically worse (higher) than the theoretical reciprocal of the fuel's calorific value.
How accurate are these conversions?
Every conversion factor used here is the exact, internationally recognized relationship between the underlying energy, mass, and power units (e.g. 1 kWh = exactly 3,600,000 joules) — results are limited only by floating-point display precision, not by rounded conversion constants.