What this converter does
This converter changes calorific (heating) value from BTU/lb to MJ/kg and back, plus kcal/kg and kJ/kg. US fuel tables quote BTU/lb, which often needs converting to SI MJ/kg. Every pair uses an exact factor. Type a value and read the answer instantly.
One thousand BTU/lb is about 2.326 MJ/kg, so a 20,000 BTU/lb gasoline is roughly 46.5 MJ/kg.
The units it covers
Specific-energy (heating-value) units, each expressed against MJ/kg.
View all units & their values
| Unit | Symbol | Value | Mainly used |
|---|---|---|---|
| Megajoule per kilogram | MJ/kg | 1 | SI heating value |
| Kilocalorie per kilogram | kcal/kg | 0.004184 | Metric fuel tables |
| BTU per pound | BTU/lb | 0.002326 | US fuel tables |
| Kilojoule per kilogram | kJ/kg | 0.001 | SI, smaller values |
The formula
Each unit has a fixed value in MJ/kg, so any pair converts through it:
result = value × factor_from ÷ factor_toWhere:
- value = the number you typed
- factor_from = the “from” unit in MJ/kg
- factor_to = the “to” unit in MJ/kg
Worked example
Convert 18,000 BTU/lb to MJ/kg.
1 BTU/lb = 0.002326 MJ/kg18,000 × 0.002326 = 41.87 MJ/kgSo a fuel at 18,000 BTU/lb has about 41.9 MJ/kg of heating value.
The units in this example
The US measure of fuel heating value, used in oil, gas and coal energy tables.
- 1 BTU/lb ≈ 0.002326 MJ/kg
- 1,000 BTU/lb ≈ 2.326 MJ/kg
- Coal ≈ 12,000 BTU/lb
- Gasoline ≈ 20,000 BTU/lb
The SI measure of specific energy or heating value — how much energy a kilogram of fuel releases.
- 1 MJ/kg ≈ 429.9 BTU/lb
- 1 MJ/kg ≈ 238.8 kcal/kg
- 1 MJ/kg = 1,000 kJ/kg
- Diesel ≈ 45 MJ/kg