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Convert Kilojoules to Therms - Energy Converter

Convert energy values between kilojoules (kJ) and therms (US) quickly and reliably. This tool uses established unit definitions (therm = 100,000 British thermal units; 1 BTU ≈ 1055.05585 J) aligned with national metrology references.

Use the converter for engineering estimates, energy-reporting reconciliation, or unit normalization when comparing fuel or heating quantities across datasets. Guidance below explains the exact relationship, recommended precision, and when to reference official standards for regulatory compliance.

Updated Nov 6, 2025

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Methodology

The conversion is derived from the chain: 1 therm (US) = 100,000 BTU and 1 BTU = 1055.05585 joules (as used in international metrology). Convert kilojoules to joules by multiplying by 1,000, then divide by the joule-equivalent of one therm.

For clarity and traceability we reference national metrology guidance and energy statistics agencies. When producing data for regulatory filing or contractual measurement, round only after verifying instrument uncertainty and any jurisdictional reporting rules.

Further resources

Expert Q&A

What is the exact conversion factor used?

This converter uses 1 therm (US) = 100,000 BTU and 1 BTU = 1055.05585 J (therm ≈ 105,505,585 J, or ≈ 105,505.585 kJ). Therefore therms = kilojoules ÷ 105,505.585.

Are there different definitions of a therm?

Yes. The most common in U.S. energy reporting is the therm (US) defined via 100,000 BTU. Other regions or legacy sources may use slightly different conventions—always confirm which therm variant your dataset or contract specifies before converting.

How many significant figures should I report?

Match the number of significant figures to the measurement uncertainty of your source data. For meter-level energy meters or invoice-level numbers, 3–4 significant figures is common; for lab calorimetry use instrument uncertainty and traceable calibration to decide. Avoid false precision.

Can I use this for regulatory or tax reporting?

This tool provides a standards-aligned numeric conversion for convenience. For formal regulatory, tax, or compliance submissions, follow the specific agency guidance and reporting rules in your jurisdiction and cite the agency-prescribed unit definitions and rounding rules.

How do I account for measurement uncertainty and calibration?

Propagate instrument uncertainty through the conversion (apply relative uncertainty to the kJ value, then convert). Ensure instruments are calibrated to a traceable standard; consult NIST or your national metrology institute for calibration best practices and accredited labs for certificates.

Why do results sometimes differ slightly from other converters?

Differences come from the base constants used (BTU definition precision, J per BTU, rounding). We use widely accepted metrology values; if you need exact parity with another dataset, align on the same base constants and rounding rules.

Sources & citations