Trades Unit Converter - Pressure, Flow, Temperature & More for Industrial Workers

How It Works

1. Select Category

   Choose a conversion category: pressure, flow, temperature, torque, length, area, volume, mass, water chemistry, or electrical. Categories are organized by trade discipline so HVAC, plumbing, instrumentation, and mechanical conversions are easy to find.

2. Enter Value and Source Unit

   Type the value you want to convert and select the source unit. For example, enter 28 and select inches of water column (inWC) to convert a pressure reading.

3. Select Target Unit

   Choose the target unit. The converter shows all available target units for the selected category. For the 28 inWC example, you can convert to PSI, kPa, bar, mbar, mmHg, atm, or other pressure units.

4. View Results

   The converted value displays instantly with full precision. The converter also shows the conversion factor and formula used, so you can verify the math manually or use the factor in a spreadsheet.

5. Use Quick-Convert Mode

   For frequently used conversions like inWC-to-PSI or F-to-C, use the quick-convert cards that show results for common reference values without selecting units each time.

Built For

• Instrument technicians converting pressure readings between inWC, PSI, kPa, bar, and mmHg during calibration
• HVAC technicians converting between SCFM and ACFM for air system sizing at altitude
• Plumbers converting between GPM and liters per minute, or grains per gallon to ppm for water hardness
• Millwrights converting torque between Newton-meters, foot-pounds, and inch-pounds during equipment assembly
• Electricians converting between mil and inches for wire sizing, or between MCM and mm2 for conductor cross-section
• Water treatment operators converting between mg/L, ppm, grains/gallon, and meq/L for chemical dosing
• Mechanical engineers converting valve Cv to Kv for metric equipment specifications

Features & Capabilities

Pressure Conversions

Convert between PSI, inWC (inches of water column), kPa, bar, mbar, mmHg (torr), atm, inHg, Pa, and kg/cm2. Includes the critical inWC-to-PSI conversion (1 PSI = 27.68 inWC) used constantly in HVAC and instrumentation work.

Flow Conversions

Convert between GPM, LPM, m3/hr, CFM, SCFM, ACFM, and ft3/hr. The SCFM/ACFM conversion accounts for altitude, temperature, and pressure differences from standard conditions. Enter your actual conditions for accurate air flow conversion.

Temperature Conversions

Convert between Fahrenheit, Celsius, Kelvin, and Rankine with the correct offset formulas. Shows the formula alongside the result so you can verify. Includes common reference points: water freezing, boiling, body temperature.

Torque Conversions

Convert between foot-pounds (ft-lbs), Newton-meters (Nm), inch-pounds (in-lbs), and kilogram-meters (kgm). Essential for bolt torque specifications, which arrive in different units depending on whether the manufacturer is domestic or metric.

Water Chemistry

Convert between ppm, mg/L, grains per gallon, meq/L, and percent concentration. The grains-per-gallon to ppm conversion (1 GPG = 17.1 ppm) is used daily in water treatment and softener sizing. Also includes alkalinity, hardness, and conductivity unit conversions.

Valve Cv/Kv Conversion

Convert between Cv (US flow coefficient) and Kv (metric flow coefficient). Cv = 1.156 times Kv. Needed when specifying or comparing valves between US and European manufacturers. An often-overlooked conversion that causes sizing errors when mixed up.

Assumptions

• SCFM standard conditions defined as 14.696 PSIA, 68\xc2\xb0F (528\xc2\xb0R), and 36% relative humidity per CAGI/ASME convention
• Water density assumed at 62.32 lb/ft\xc2\xb3 (60\xc2\xb0F) for volumetric flow conversions involving GPM and LPM
• Pressure conversions use exact defined relationships (e.g., 1 atm = 14.696 PSI = 101.325 kPa = 760 mmHg)
• Temperature conversions use exact offset formulas (\xc2\xb0F = \xc2\xb0C \xc3\x97 9/5 + 32; K = \xc2\xb0C + 273.15)
• Cv/Kv conversion factor of 1.156 based on ISA/IEC definitions using water at specified reference conditions
• Water chemistry ppm assumed equivalent to mg/L for dilute aqueous solutions at standard temperature and pressure

Limitations

• SCFM to ACFM conversion requires user-entered actual pressure, temperature, and altitude — defaults to sea level if not specified
• Does not account for gas compressibility factors (Z-factor) for non-ideal gas behavior at high pressures or cryogenic temperatures
• Water chemistry conversions assume dilute solutions — concentrated brines and chemical solutions require density corrections
• Cv/Kv conversion applies to liquid flow only — gas and steam Cv calculations require additional factors (expansion factor, specific heat ratio)
• Electrical unit conversions do not account for power factor, harmonics, or phase angle for AC circuit calculations
• Does not include viscosity, density, or other fluid property conversions beyond the listed categories

References

• NIST Special Publication 811 — Guide for the Use of the International System of Units (SI)
• CAGI/ASME — Standard conditions for compressed air flow measurement (14.696 PSIA, 68\xc2\xb0F)
• ISA-75.01.01 — Industrial-Process Control Valves: Flow Equations for Sizing (Cv/Kv definitions)
• IEC 60534-2-1 — Industrial-Process Control Valves: Flow Capacity (metric Kv standard)
• AWWA B100 — Granular Filter Material (grains per gallon to ppm conversion for water treatment)
• ASHRAE Handbook — Fundamentals, Chapter 1: Psychrometrics (SCFM/ACFM altitude and temperature corrections)

Frequently Asked Questions