Calculator Methodology

Direct converters use fixed physical relationships between compatible units. Power units convert through watts; energy units convert through joules. Values stay at full JavaScript numeric precision during calculation and are rounded only for display.

A conversion is permitted only when the source and destination describe the same physical quantity. BTU is energy, while BTU/hr is power. Multi-input calculators first combine inputs into the required dimension—for example, BTU/lb multiplied by lb/hr produces BTU/hr—before converting the result.

• Blank, non-numeric, negative, infinite, and unsupported values are rejected.
• Comma decimal input is normalized when it is unambiguous.
• Reasonable upper limits protect the interface from meaningless overflow.
• Intermediate values are never rounded before the final displayed result.
• Scientific notation is used for extremely small or large results.

Direct unit conversions are mathematical equivalences. Sizing, efficiency, airflow, fuel, and equipment calculators are estimates because real installations depend on construction, climate, operating conditions, manufacturer ratings, losses, codes, and measurement quality. Each calculator states its important assumptions beside the tool.

• Check the formula and dimensions independently.
• Verify representative normal, boundary, reverse, and rounding cases.
• Compare constants with recognized SI and engineering definitions.
• Review visible units, examples, FAQs, metadata, and structured data together.
• Record the public review date and correct reported errors promptly.

To report a suspected error, use the contact page and include the calculator URL, inputs, displayed result, and expected result.

• NIST Guide to the SI, Appendix B.9 conversion factors
• U.S. Energy Information Administration natural-gas unit definitions
• U.S. Department of Energy definitions for kilowatts, kilowatt-hours, therms, and heat rate
• ASHRAE terminology for cooling capacity, equipment capacity, EER, and COP