Engineering Unit Conversion Factors

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Unit Conversion Calculator for SI and British Unit

  • Boiler & Process Engineering Unit Converter

  • What’s included (9 categories, 65+ unit pairs):

    Category Examples
     Temperature °C ↔ °F, K ↔ °R, LMTD
     Pressure bar/kPa/MPa/Pa ↔ psi, psig, in H₂O
     Heat Transfer k, h, heat flux, Cp, fouling resistance
     Power / Heat Rate kW, MW, BHP ↔ BTU/h, MMBTU/h, hp
    Energy / Enthalpy kJ, MJ ↔ BTU, MMBTU, specific enthalpy, latent heat
     Fluid Properties viscosity (Pa·s, cP), density, surface tension
     Flow Rates m³/h, L/s, kg/h, t/h ↔ GPM, CFM, lb/h
     Dimensions & Velocity m, mm, m², m³, m/s ↔ ft, in, ft², ft³, ft/s
     Mass & Force kg, tonne, N, kN ↔ lb, ton, lbf

 

Most Important Conversion Factors for Process BOE, Energy Auditor

  • These are the conversion factors most frequently used in Boiler Operation Engineer (BOE), Energy Auditor, Energy Manager, Thermal Power Plant, and Combustion Engineering calculations.

 Pressure Conversions

Unit Equivalent
1 atm 1.013 bar
1 atm 101.325 kPa
1 bar 100 kPa
1 MPa 10 bar
1 kg/cm² 0.9807 bar
1 bar 1.0197 kg/cm²
1 psi 6.895 kPa
1 bar 14.5 psi
1 mmWC 9.81 Pa
1 mWC 9.81 kPa

BOE Shortcut

  • 1 bar ≈ 1 kg/cm²
  • 15 psi ≈ 1 bar

 Temperature Conversions

Formula Conversion
°F = (°C × 9/5) + 32 Celsius to Fahrenheit
°C = (°F − 32) × 5/9 Fahrenheit to Celsius
K = °C + 273 Celsius to Kelvin
°C = K − 273 Kelvin to Celsius

Important Values

°C °F
0 32
100 212
200 392
400 752
600 1112

 Heat and Energy Conversions

Unit Equivalent
1 kcal 4.187 kJ
1 kJ 0.239 kcal
1 MJ 239 kcal
1 kWh 860 kcal
1 kWh 3.6 MJ
1 kcal 3.968 BTU
1 BTU 1.055 kJ
1 MJ 947.8 BTU

BOE Shortcut

  • 1 kWh = 860 kcal
  • 1 kcal = 4.187 kJ

Power Conversions

Unit Equivalent
1 HP 0.746 kW
1 kW 1.341 HP
1 MW 1000 kW
1 Boiler HP 9.81 kW
1 TR 3.517 kW

Important Values

HP kW
10 7.46
50 37.3
100 74.6
500 373

 Steam Generation Conversions

Unit Equivalent
1 TPH 1000 kg/hr
1 kg/s 3600 kg/hr
1 kg/hr 0.000278 kg/s
1 TPH 0.278 kg/s
1 lb/hr 0.4536 kg/hr

BOE Shortcut

  • 10 TPH = 10,000 kg/hr
  • 1 kg/s = 3.6 TPH

 Flow Rate Conversions

Unit Equivalent
1 m³/hr 0.278 L/s
1 L/s 3.6 m³/hr
1 GPM 0.227 m³/hr
1 m³/hr 4.4 GPM
1 CFM 1.699 m³/hr
1 m³/min 35.31 CFM

 Length, Area and Volume

Length

Unit Equivalent
1 inch 25.4 mm
1 ft 0.3048 m
1 m 3.281 ft

Area

Unit Equivalent
1 m² 10.764 ft²
1 ft² 0.0929 m²

Volume

Unit Equivalent
1 m³ 1000 litres
1 litre 0.001 m³
1 ft³ 0.0283 m³
1 m³ 35.31 ft³

 Fuel Calorific Value Conversions

Unit Equivalent
1 kcal/kg 4.187 kJ/kg
1 MJ/kg 238.85 kcal/kg
1 kcal/Nm³ 4.187 kJ/Nm³
1 MJ/Nm³ 238.85 kcal/Nm³

Typical Fuel Heating Values

Fuel GCV
Coal 3500–6500 kcal/kg
Biomass 3000–4500 kcal/kg
Bagasse 2200–2500 kcal/kg
Furnace Oil 10,000–10,500 kcal/kg
Diesel 10,500–11,000 kcal/kg
LPG 11,000–12,000 kcal/kg
Natural Gas 8500–9500 kcal/Nm³

Air and Combustion Conversions

Parameter Value
Oxygen in Air 21%
Nitrogen in Air 79%
Air Density 1.2 kg/m³
CO₂ in Dry Flue Gas (Theoretical) 18–20%
Excess Air for Oil Firing 10–20%
Excess Air for Coal Firing 20–40%

Important Combustion Relation

Air to  Fuel Ratio=Mass of Air / Mass of Fuel

 Frequently Used Boiler Constants

Parameter Value
Density of Water 1000 kg/m³
Specific Heat of Water 1 kcal/kg°C
Specific Heat of Air 0.24 kcal/kg°C
Latent Heat of Steam at 100°C 539 kcal/kg
Atmospheric Pressure 1.013 bar
Gravity (g) 9.81 m/s²
Stefan-Boltzmann Constant 5.67 × 10⁻⁸ W/m²K⁴

Top 20 BOE Exam Conversion Factors to Memorize

  • 1 kcal = 4.187 kJ
  • 1 kWh = 860 kcal
  • 1 HP = 0.746 kW
  • 1 bar = 100 kPa
  • 1 bar = 14.5 psi
  • 1 kg/cm² = 0.98 bar
  • 1 atm = 1.013 bar
  • 1 MPa = 10 bar
  • 1 TPH = 1000 kg/hr
  • 1 kg/s = 3600 kg/hr
  • 1 m³ = 1000 litres
  • 1 inch = 25.4 mm
  • 1 ft = 0.3048 m
  • 1 m² = 10.764 ft²
  • 1 m³ = 35.31 ft³
  • 1 TR = 3.517 kW
  • 1 Boiler HP = 9.81 kW
  • 1 BTU = 1.055 kJ
  • Density of water = 1000 kg/m³
  • Latent heat of steam = 539 kcal/kg

These 20 conversions cover most numerical problems encountered in BOE, Energy Auditor, boiler performance, furnace efficiency, steam generation, and combustion calculations.

Most Important SI to BTU Unit Conversions

The following table contains the most commonly used SI-to-BTU conversions in boiler, furnace, combustion, and thermal engineering calculation Heat and Energy Conversions

SI Unit BTU Unit Equivalent
1 kJ 0.9478 BTU
1 MJ 947.8 BTU
1 BTU 1.055 kJ
1 kcal 3.968 BTU
1 BTU 0.252 kcal
1 kWh 3412 BTU
1 MWh 3.412 × 10⁶ BTU
1 GJ 947,817 BTU

Power and Heat Rate Conversions

SI Unit BTU Unit Equivalent
1 W 3.412 BTU/hr
1 kW 3412 BTU/hr
1 MW 3.412 × 10⁶ BTU/hr
1 HP 2545 BTU/hr
1 BTU/hr 0.293 W
1 TR (Ton Refrigeration) 12,000 BTU/hr
1 TR 3.517 kW

Steam and Boiler Conversions

SI Unit BTU Unit Equivalent
1 kg Steam (Latent Heat) ≈ 970 BTU
1 kg/hr Steam 2.205 lb/hr
1 TPH Steam 2204.6 lb/hr
1 kcal/kg Enthalpy 3.968 BTU/lb
1 kJ/kg Enthalpy 0.430 BTU/lb

Fuel Heating Value Conversions

SI Unit BTU Unit Equivalent
1 kcal/kg 1.8 BTU/lb
1 MJ/kg 430 BTU/lb
1 kJ/kg 0.430 BTU/lb
1 kcal/Nm³ 0.112 BTU/scf
1 MJ/Nm³ 25.4 BTU/scf

Typical Fuel Heating Values

Fuel SI Unit BTU Unit
Coal 5000 kcal/kg 9000 BTU/lb
Furnace Oil 10,200 kcal/kg 18,400 BTU/lb
Diesel 10,700 kcal/kg 19,300 BTU/lb
LPG 11,500 kcal/kg 20,700 BTU/lb
Natural Gas 9000 kcal/Nm³ 1015 BTU/scf

Pressure Conversions

SI Unit Imperial Unit
1 bar 14.5 psi
1 kPa 0.145 psi
1 MPa 145 psi
1 kg/cm² 14.22 psi
1 psi 6.895 kPa

Temperature Conversions

SI Temperature Imperial Temperature
°F = (°C × 9/5) + 32 Celsius → Fahrenheit
°C = (°F − 32) × 5/9 Fahrenheit → Celsius
K = °R × 5/9 Rankine → Kelvin
°R = °F + 459.67 Fahrenheit → Rankine

Common Boiler Temperatures

°C °F
100 212
150 302
200 392
300 572
400 752
500 932

Flow Rate Conversions

SI Unit Imperial Unit
1 m³/hr 35.31 ft³/hr
1 m³/min 35.31 CFM
1 Nm³/hr 0.589 SCFM
1 L/s 2.119 CFM
1 m³/hr 4.403 GPM

Length and Area Conversions

SI Unit Imperial Unit
1 mm 0.03937 in
1 m 3.281 ft
1 m² 10.764 ft²
1 m³ 35.315 ft³
1 inch 25.4 mm

Quick BOE Memory Table

Conversion Value
1 kWh 3412 BTU
1 kcal 3.968 BTU
1 kJ 0.948 BTU
1 HP 2545 BTU/hr
1 kW 3412 BTU/hr
1 bar 14.5 psi
1 MPa 145 psi
1 kg 2.205 lb
1 m³ 35.31 ft³
1 TPH 2205 lb/hr
1 TR 12,000 BTU/hr

These conversions are among the most frequently used in BOE examinations, ASME boiler calculations, furnace heat-balance calculations, combustion engineering, and thermal power plant performance analysis.