HVAC Unit Converter
Convert:
Cooling capacity (TR, kW, BTU/h) | Airflow (CFM, L/s, m³/h) | Pressure (Pa, mmWC, in.WC) | Temperature (°C, °F, K) | Velocity (m/s, FPM) | Power (kW, HP)
HVAC Unit Converter
Instant, standards-based conversions for HVAC design, commissioning and site work.
Cooling capacity
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HVAC Unit Conversion Reference
This HVAC engineering calculator combines cooling, airflow and pressure converter modules with a practical reference for load calculations, air balancing, equipment selection and MEP design reviews.
What is a Refrigeration Ton?
A refrigeration ton (TR) is a unit of cooling capacity, not equipment weight. One TR equals 12,000 International Table BTU per hour, or approximately 3.51685 kW of cooling.
TR vs kW
TR and cooling kW both describe the rate of heat removal. Convert TR to cooling capacity in kW by multiplying by 3.51685. This is different from the electrical input power of an air-conditioning unit.
BTU vs Watts
A BTU is an amount of energy; BTU/h is a rate of heat transfer. HVAC capacity should therefore be written as BTU/h. One watt of heat-transfer rate equals approximately 3.41214 BTU/h.
Common HVAC Unit Conversions
| Engineering quantity | Common conversion | Typical use |
|---|---|---|
| Cooling capacity | 1 TR = 3.51685 kW | Chillers, DX units and load schedules |
| Cooling capacity | 12,000 BTU/h = 1 TR | Residential and commercial AC ratings |
| Airflow | 1 CFM = 0.471947 L/s | Diffusers, fans and ventilation |
| Airflow | 1 CFM = 1.69901 m³/h | AHUs and duct systems |
| Pressure | 1 Pa = 0.101972 mmWC | Duct static pressure and filters |
| Velocity | 1 m/s = 196.850 FPM | Duct and grille air velocity |
| Area | 1 m² = 10.7639 ft² | Room and envelope calculations |
Frequently Asked Questions
How do I convert TR to kW?
Multiply refrigeration tons by 3.51685. For example, 5 TR is approximately 17.5843 kW of cooling capacity.
How do I convert BTU/h to kW?
Multiply BTU/h by 0.000293071. For example, 24,000 BTU/h is approximately 7.0337 kW.
How do I convert CFM to L/s?
Multiply CFM by 0.471947. For example, 1,000 CFM is approximately 471.947 L/s.
How do I convert CFM to m³/h?
Multiply CFM by 1.69901. For example, 500 CFM is approximately 849.505 m³/h.
How do I convert Pa to mmWC?
Divide pascals by 9.80665. Therefore, 100 Pa is approximately 10.1972 mmWC using the conventional water-column definition.
Which horsepower definition is used?
The HP option uses mechanical horsepower: 1 HP equals approximately 745.700 W. Metric horsepower is a different unit and is not treated as HP.
Engineering References
Related BuildMEP Engineering Tools
HVAC Engineering Unit Converter
The HVAC Engineering Unit Converter is a free online engineering tool developed by BuildMEP to simplify everyday HVAC and MEP calculations. Whether you are designing an air conditioning system, preparing equipment schedules, reviewing shop drawings, or commissioning a building, accurate unit conversion is essential for making reliable engineering decisions.
HVAC projects often involve both SI (International System of Units) and Imperial units. Manufacturers, consultants, contractors, and project specifications may all use different measurement systems. For example, cooling capacity may be specified in refrigeration tons (TR), kilowatts (kW), or BTU/h, while airflow can be expressed in CFM, L/s, or m³/h. This converter allows you to switch instantly between these units without performing manual calculations.
The BuildMEP HVAC Engineering Unit Converter combines multiple engineering conversion modules into a single, easy-to-use interface. It supports common HVAC engineering quantities including cooling capacity, airflow, pressure, temperature, velocity, power, length, area, and volume. Each conversion is calculated using internationally accepted conversion factors to provide accurate and consistent results.
Whether you are an HVAC engineer, MEP consultant, facility manager, technician, student, or commissioning specialist, this tool is designed to save time, reduce calculation errors, and improve engineering productivity.
Cooling Capacity Unit Conversion (TR, kW & BTU/h)
Cooling capacity is one of the most frequently converted engineering quantities in the HVAC industry. Equipment manufacturers, consultants, and project specifications often use different units depending on the country, design standard, or product catalog. Understanding how these units relate to each other helps engineers compare equipment accurately and select the correct cooling capacity for each application.
The three most common cooling capacity units are Refrigeration Ton (TR), kilowatt (kW), and British Thermal Unit per hour (BTU/h). While these units represent the same cooling effect, they are expressed using different measurement systems. Modern international projects generally use kilowatts, whereas many manufacturers still publish air conditioning capacities in refrigeration tons or BTU/h.
One refrigeration ton is historically defined as the amount of heat required to melt one ton of ice over a 24-hour period. Today, it is internationally standardized as 12,000 BTU/h, which is approximately 3.51685 kW. This relationship is widely used for selecting DX units, chillers, VRF systems, packaged units, and other air conditioning equipment.
Using accurate conversion factors eliminates manual calculation errors and ensures equipment schedules remain consistent throughout the design process. The BuildMEP HVAC Engineering Unit Converter performs these calculations instantly, allowing engineers to switch between refrigeration tons, kilowatts, BTU/h, watts, and kcal/h with confidence.
Common Cooling Capacity Conversion Factors
| Conversion | Value |
|---|---|
| 1 TR | 3.51685 kW |
| 1 TR | 12,000 BTU/h |
| 1 kW | 0.2843 TR |
| 1 kW | 3,412.14 BTU/h |
| 1 BTU/h | 0.000293071 kW |
Airflow Unit Conversion (CFM, L/s & m³/h)
Airflow is one of the most important design parameters in HVAC systems. It determines how much conditioned air is delivered to a space and directly affects occupant comfort, indoor air quality, equipment performance, and energy efficiency. During HVAC design, engineers frequently convert airflow values between different unit systems depending on project requirements, equipment documentation, and local engineering practices.
The most commonly used airflow units are Cubic Feet per Minute (CFM), Litres per Second (L/s), Cubic Metres per Hour (m³/h), and Cubic Metres per Second (m³/s). While CFM remains popular in North America and many manufacturer catalogues, SI units such as L/s and m³/h are widely used in international projects and specifications.
Engineers regularly perform airflow conversions when selecting air handling units (AHUs), fan coil units (FCUs), ventilation fans, diffusers, grilles, ducts, and air distribution systems. Accurate airflow conversion also plays an important role during air balancing, TAB (Testing, Adjusting and Balancing), commissioning, and system performance verification.
The BuildMEP HVAC Engineering Unit Converter provides instant airflow conversions using internationally accepted conversion factors. This eliminates manual calculations and ensures consistent engineering documentation throughout the project lifecycle.
Common Airflow Conversion Factors
| Conversion | Value |
|---|---|
| 1 CFM | 0.4719 L/s |
| 1 CFM | 1.699 m³/h |
| 1 L/s | 2.119 CFM |
| 1 m³/h | 0.5886 CFM |
| 1 m³/s | 2118.88 CFM |
- Air Handling Units (AHUs)
- Fan Coil Units (FCUs)
- Ventilation Fans
- Fresh Air Systems
- Kitchen Exhaust Systems
- Duct Design and Air Balancing
Pressure Unit Conversion (Pa, mmWC, in.WC & psi)
Pressure is a critical parameter in HVAC system design and commissioning. Engineers use pressure measurements to evaluate fan performance, calculate duct pressure losses, size filters, verify pump operation, and balance air and water systems. Because different manufacturers and international standards use different pressure units, engineers frequently need to convert between multiple measurement systems during a project.
The most common HVAC pressure units include Pascal (Pa), kilopascal (kPa), millimetres of Water Column (mmWC), inches of Water Column (in.WC), bar, and pounds per square inch (psi). While SI projects generally specify pressure in Pascals, many fan manufacturers and HVAC equipment catalogues still reference inches or millimetres of water column.
Pressure conversion is commonly required when selecting supply and exhaust fans, verifying filter pressure drop, calculating external static pressure for air handling units (AHUs), commissioning ventilation systems, and reviewing manufacturer performance curves. Using the correct pressure unit ensures accurate comparison between design documents and equipment data.
The BuildMEP HVAC Engineering Unit Converter performs pressure conversions instantly using internationally recognised conversion factors, helping engineers avoid manual calculation errors while maintaining consistent engineering documentation.
Common Pressure Conversion Factors
| Conversion | Value |
|---|---|
| 1 Pa | 0.10197 mmWC |
| 1 mmWC | 9.80665 Pa |
| 1 in.WC | 249.09 Pa |
| 1 kPa | 1000 Pa |
| 1 psi | 6894.76 Pa |
| 1 bar | 100,000 Pa |
- Supply and exhaust fan selection
- External static pressure calculations
- Filter pressure drop verification
- Duct pressure loss calculations
- Air balancing and TAB (Testing, Adjusting & Balancing)
- Pump differential pressure measurements
Temperature & Velocity Unit Conversion (°C, °F, K, m/s & FPM)
Temperature and air velocity are fundamental measurements in HVAC system design, commissioning, and troubleshooting. Engineers use these values to evaluate thermal comfort, equipment performance, ventilation effectiveness, and air distribution. Since projects and equipment manufacturers may use either SI or Imperial units, accurate conversion between these measurement systems is essential.
Temperature is commonly expressed in Degrees Celsius (°C), Degrees Fahrenheit (°F), and Kelvin (K). Celsius is the standard unit for most international HVAC projects, while Fahrenheit remains widely used in North America. Kelvin is primarily used in engineering calculations, scientific analysis, and thermodynamic equations where absolute temperature is required.
Air velocity is typically measured in metres per second (m/s) or feet per minute (FPM). HVAC engineers use velocity measurements when designing duct systems, selecting air terminals, balancing ventilation systems, and verifying airflow during commissioning. Maintaining appropriate air velocity helps reduce noise, minimize pressure losses, and improve occupant comfort.
The BuildMEP HVAC Engineering Unit Converter instantly converts temperature and velocity values using internationally accepted conversion standards. This helps engineers work confidently with project specifications, manufacturer documentation, testing reports, and commissioning data regardless of the unit system used.
Common Temperature Conversion Factors
| Conversion | Formula |
|---|---|
| °C → °F | (°C × 9/5) + 32 |
| °F → °C | (°F − 32) × 5/9 |
| °C → K | °C + 273.15 |
| K → °C | K − 273.15 |
Common Velocity Conversion Factors
| Conversion | Value |
|---|---|
| 1 m/s | 196.85 FPM |
| 1 FPM | 0.00508 m/s |
- Supply and return air temperature measurements
- Air diffuser and grille performance testing
- Duct velocity calculations
- Ventilation balancing and commissioning
- Indoor comfort verification
- Equipment performance analysis
Common HVAC Engineering Conversion Table
Although the BuildMEP HVAC Engineering Unit Converter provides instant live conversions, engineers often need a quick reference during equipment selection, design reviews, commissioning, or site inspections. The following table summarizes some of the most commonly used HVAC engineering conversion factors. These values are based on internationally accepted engineering standards and are widely used throughout the HVAC and MEP industry.
| Engineering Quantity | Conversion | Equivalent Value |
|---|---|---|
| Cooling Capacity | 1 TR | 3.51685 kW |
| Cooling Capacity | 1 TR | 12,000 BTU/h |
| Cooling Capacity | 1 kW | 3,412.14 BTU/h |
| Cooling Capacity | 1 kW | 0.2843 TR |
| Airflow | 1 CFM | 0.4719 L/s |
| Airflow | 1 CFM | 1.699 m³/h |
| Airflow | 1 L/s | 2.119 CFM |
| Pressure | 1 Pa | 0.10197 mmWC |
| Pressure | 1 in.WC | 249.09 Pa |
| Pressure | 1 psi | 6894.76 Pa |
| Velocity | 1 m/s | 196.85 FPM |
| Velocity | 1 FPM | 0.00508 m/s |
| Power | 1 HP | 0.746 kW |
| Power | 1 kW | 1.341 HP |
| Length | 1 inch | 25.4 mm |
| Length | 1 ft | 0.3048 m |
| Area | 1 m² | 10.764 ft² |
| Volume | 1 m³ | 35.315 ft³ |
| Temperature | °C → °F | (°C × 9/5) + 32 |
| Temperature | °F → °C | (°F − 32) × 5/9 |
While these reference values are useful for quick engineering checks, using the interactive BuildMEP HVAC Engineering Unit Converter ensures higher precision, reduces manual calculation errors, and supports a wider range of engineering units commonly encountered in HVAC, MEP, and building services projects.
Practical Engineering Tips for HVAC Unit Conversion
Accurate unit conversion is an essential part of HVAC engineering, but understanding when and how to apply different units is equally important. The following practical tips are based on common engineering practice and can help reduce design errors, improve communication between project teams, and simplify equipment selection.
1. Verify Units Before Comparing Equipment
Manufacturers often publish similar equipment using different unit systems. One catalogue may list cooling capacity in refrigeration tons (TR), while another uses kilowatts (kW). Always convert both values into the same unit before comparing performance or preparing equipment schedules.
2. Keep a Consistent Unit System
During HVAC design, use a single measurement system throughout calculations whenever possible. Mixing SI and Imperial units increases the risk of conversion mistakes, especially when multiple engineers collaborate on the same project.
3. Understand Manufacturer Documentation
International manufacturers may publish technical data in different units depending on the target market. Always confirm whether airflow, pressure, and cooling capacity values match your project specifications before selecting equipment.
4. Avoid Excessive Rounding
While rounded values are acceptable for quick estimates, detailed engineering calculations should maintain sufficient decimal precision. Small rounding differences can accumulate when sizing chillers, ducts, pumps, or ventilation systems.
5. Use the Correct Pressure Unit
Fans, filters, and duct systems commonly use Pascals (Pa), millimetres of water column (mmWC), or inches of water column (in.WC). Always verify which unit is used in manufacturer performance curves before comparing static pressure values.
6. Check Airflow Units Carefully
Airflow is commonly expressed as CFM, L/s, m³/h, or m³/s. Incorrect airflow conversion can affect duct sizing, diffuser selection, ventilation calculations, and indoor air quality performance.
7. Review Conversion Results Before Final Design
Unit conversion tools are excellent for improving productivity, but final equipment selection should always be reviewed against project specifications, manufacturer data, and applicable engineering standards. A quick verification step helps prevent costly design or procurement errors.
Frequently Asked Questions (FAQ)
Below are answers to some of the most common questions about HVAC engineering unit conversions, cooling capacity, airflow, pressure, and engineering calculations.
1. What is an HVAC Engineering Unit Converter?
An HVAC Engineering Unit Converter is an online tool that converts engineering units commonly used in heating, ventilation, and air conditioning systems. It allows engineers to convert cooling capacity, airflow, pressure, temperature, velocity, power, length, area, and volume quickly and accurately.
2. What is 1 Refrigeration Ton (TR) in kW?
One refrigeration ton (1 TR) is equal to 3.51685 kW. It is also equivalent to 12,000 BTU/h and is one of the most commonly used cooling capacity units in HVAC engineering.
3. What is the difference between TR and kW?
Both units represent cooling capacity. TR is a traditional HVAC unit based on the cooling effect of melting one ton of ice in 24 hours, while kW is the SI unit of power used internationally for engineering calculations.
4. Why do HVAC engineers convert between CFM and L/s?
CFM is widely used in North America, while litres per second (L/s) is commonly used in international projects. Converting between these units ensures consistent airflow calculations and equipment selection across different standards.
5. What pressure units are commonly used in HVAC?
The most common HVAC pressure units are Pascal (Pa), kilopascal (kPa), millimetres of water column (mmWC), inches of water column (in.WC), psi, and bar. The required unit depends on the project specification and equipment manufacturer.
6. Can I use this converter for HVAC design calculations?
Yes. The converter provides accurate engineering unit conversions that are suitable for design, equipment selection, commissioning, and educational purposes. However, unit conversion is only one part of the overall engineering design process.
7. Why do manufacturers use different engineering units?
Manufacturers often publish technical data based on regional standards. North American catalogues frequently use Imperial units such as CFM and BTU/h, while international projects generally use SI units such as kW, L/s, and Pascals.
8. How accurate is the BuildMEP HVAC Engineering Unit Converter?
The converter uses internationally accepted conversion factors and provides accurate results for common HVAC engineering applications. Always verify project-specific values and manufacturer data before final equipment selection.
9. Is this HVAC Engineering Unit Converter free?
Yes. The BuildMEP HVAC Engineering Unit Converter is completely free to use without registration or subscription.
10. Who can use this converter?
This tool is designed for HVAC engineers, MEP consultants, facility managers, commissioning engineers, technicians, contractors, engineering students, and anyone working with HVAC system calculations.
Engineering References
The conversion factors and engineering information used throughout this HVAC Engineering Unit Converter are based on internationally recognized standards and widely accepted engineering references. While this tool provides accurate engineering conversions for everyday HVAC applications, engineers should always refer to the latest project specifications, applicable codes, and manufacturer documentation when performing detailed system design.
| Reference | Description |
|---|---|
| ASHRAE Handbook – Fundamentals | Industry reference for HVAC design principles, psychrometrics, cooling load calculations, and engineering practices. |
| ASHRAE Standards | Guidelines for ventilation, thermal comfort, energy efficiency, and indoor environmental quality. |
| NIST (National Institute of Standards and Technology) | Official SI unit definitions and internationally accepted conversion standards. |
| ISO 80000 | International standard for quantities, units, and engineering notation. |
| Manufacturer Technical Catalogues | Equipment performance data published by HVAC manufacturers for engineering selection and verification. |
BuildMEP continuously reviews and updates its engineering tools to ensure they remain practical, accurate, and useful for HVAC professionals, consultants, technicians, and engineering students.
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