BTU to Kilojoules Converter Calculator

Convert British thermal units to kilojoules with precise factors select IT or thermochemical modes adjust rounding view reverse calculation copy results instantly see formulas and constants clearly enjoy batch entry paste lists handle scientific notation get engineering prefixes optional output precision and trustworthy results in a clean responsive layout with accessibility checks and tooltips

1 BTU = 1055.055853 J
International energy unit based on heat required to raise water temperature.
Kilojoule equals 1000 joules. SI energy unit.
Batch mode

Paste numbers separated by spaces commas semicolons or new lines. Uses current direction and BTU definition.

Formulas

BTU → kJ: kJ = BTU × (1055.055853 J / BTU) ÷ 1000

kJ → BTU: BTU = kJ × 1000 ÷ (1055.055853 J / BTU)

Selected definition: International Table BTU (IT)

Notes
  • Energy equality: 1 kJ = 1000 J.
  • Common BTU definitions vary slightly; pick the one required by your standard or data sheet.
  • Scientific format uses %.E with your chosen decimals.
  • Batch mode skips tokens that are not valid numbers.

Frequently Asked Questions

Which BTU definition should I choose?
Use IT for most engineering contexts and heating equipment. Use thermochemical when your source data uses thermochemical calories. Mean BTU appears in some legacy tables.
How accurate are the constants?
The IT and thermochemical constants are standard values to many significant figures. You can control rounding via the decimals setting to match reporting requirements.
Can I convert in both directions?
Yes. Choose the desired direction from the selector to compute BTU to kJ or kJ to BTU. Both single and batch conversions support either direction.
What input formats are accepted?
You can enter plain decimals or scientific notation such as 1.23e6. Batch mode accepts values separated by spaces commas semicolons or new lines.
How is scientific notation displayed?
When the Scientific switch is enabled the calculator formats outputs with exponential notation using the number of decimals you specify.
Does the tool support copyable outputs?
Yes. Use the Copy Out buttons near the result fields or Copy Table to grab the batch results for spreadsheets and reports.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.