HVAC and Refrigeration Converters

Browse 15 published tools in HVAC and Refrigeration Converters. Select the source and destination unit that match your measurement. Each generated calculator shows a formula, worked examples, a conversion table and detailed answers so you can check the relationship before using the result.

Choosing a unit convention

Read the unit definition beside the calculator. The same everyday name can describe a different regional or industry standard. Keep the original unit and its convention with the converted value. A unit change does not determine a missing density, duration, market rate or material property.

Energy and power describe different quantities

Energy is an amount, while power is the rate at which energy is transferred or used. Watts measure power. Watt-hours and kilowatt-hours measure energy. One kilowatt-hour is 3.6 million joules. A device rated at a given wattage does not have a fixed kilowatt-hour consumption without a duration and operating behaviour. A unit conversion from watts to horsepower can use a fixed factor because both describe power, but watts to kilowatt-hours needs time. Appliance ratings can also describe maximum, nominal or average power, so a conversion of the rating should retain that description.

Calorie, horsepower and BTU conventions

A thermochemical calorie is 4.184 joules, and a kilocalorie is one thousand calories. Food labels often call a kilocalorie a Calorie, so context is essential when comparing nutritional and physics measurements. Mechanical horsepower is approximately 745.7 watts and differs from metric horsepower. BTU values can use several historical conventions; this site uses the International Table definition where stated. Refrigeration tonnage describes cooling power rather than a mass of equipment. A numerical result is meaningful only when its convention matches the original specification. Check the qualifiers on supplier data and choose an explicitly compatible conversion.

US customary and imperial liquid measures

The US liquid gallon is 3.785411784 litres, while the imperial gallon is 4.54609 litres. Their pints and fluid ounces also differ. A US fluid ounce is a volume measurement and should not be confused with an ounce of mass. Cooking cups add further conventions: a US customary cup is approximately 236.588 millilitres, a metric cup is 250 millilitres, and an imperial cup is approximately 284.131 millilitres. A recipe translated between countries may therefore need more than a change in spelling. This page states its default liquid convention. Choose an explicitly qualified unit whenever the source document specifies a system.

Volume, density and flow-rate context

Litres and cubic metres measure volume. Grams and kilograms measure mass. Converting between mass and volume needs the density of the substance under the relevant conditions. A cup of flour and a cup of water can have different masses even though their volumes match. Flow rates add a time denominator: litres per minute and litres per hour describe the same type of quantity at different scales, while litres alone describe an amount. A volume conversion does not calculate how quickly a container fills. Confirm whether a meter reports instantaneous flow, an average rate or a cumulative amount before using a conversion in a process calculation.

Temperature readings versus temperature differences

An absolute temperature reading locates a point on a scale, while a temperature difference describes the interval between two readings. Celsius and Fahrenheit readings require both a multiplier and an offset. A Celsius temperature difference uses a multiplier of 1.8 to become a Fahrenheit temperature difference, without adding 32. Celsius and Kelvin intervals have the same size, even though their zero points differ by 273.15. This calculator converts readings. When describing heating, cooling or a temperature rise, check whether you need an interval calculation instead. Applying the reading offset to a temperature difference produces the wrong physical interpretation.

Absolute zero and instrument accuracy

Absolute zero corresponds to 0 kelvin, −273.15 degrees Celsius and −459.67 degrees Fahrenheit. The calculator rejects readings below these limits. A sensor’s calibration, range and resolution still govern the reliability of its reported temperature. Expressing a thermometer reading on another scale does not improve its calibration. An oven dial, ambient thermometer and laboratory probe can have very different tolerances. Follow the manufacturer’s instructions or the applicable protocol when choosing a reporting precision. The conversion equation describes the relationship between scales, while the instrument documentation describes how confidently the original reading is known.

Checking and reporting your answer

Use a one-unit reference value to confirm the conversion direction, then compare a worked example with your own arithmetic. Keep intermediate digits and round the final answer according to the accuracy of the original measurement. Include the destination unit in a report or spreadsheet header. For work governed by a contract, protocol or technical standard, follow that document’s definition and validation requirements.