Flow Measurement · Free Calculator
Gas Flow to Energy Calculator
Convert a fuel gas flow into energy rate using its calorific value, for burner sizing, energy reporting and custody transfer checks.
Calorific valuekW and MMBtu/hNatural gasEnergy reporting
Nm³/h
MJ/Nm³
h
Energy rate5,416.7 kW
Energy rate19,500 MJ/h
Energy rate18.48 MMBtu/h
Energy rate184.8 therm/h
Energy per day130 MWh (468 GJ)
BasisGross (HHV)
How this result was calculated
- Energy = Q × CV = 500 × 39 = 19,500 MJ/h
- kW = MJ/h ÷ 3.6 = 5,416.7 kW
- 1 MMBtu = 1055.056 MJ; 1 therm = 105.5056 MJ
Advertisement
Energy Flow Formula
Energy rate (MJ/h) = Q × CV
kW = MJ/h ÷ 3.6
MMBtu/h = MJ/h ÷ 1055.056
kW = MJ/h ÷ 3.6
MMBtu/h = MJ/h ÷ 1055.056
Q is the gas flow at the same reference conditions as the calorific value CV (for example Nm³ at 0 °C or Sm³ at 15 °C), and CV the gross or net calorific value from the gas analysis or supplier. Natural gas is often around 37 to 42 MJ/Nm³ gross, but use your actual value.
Worked example
500 Nm³/h of natural gas with a gross CV of 39 MJ/Nm³ delivers 19,500 MJ/h, about 5,417 kW or 18.48 MMBtu/h.
Key insight: gas is often billed on energy, not volume. A flow meter with the wrong reference conditions, or a CV on the wrong basis, can shift energy figures by several percent.
Advertisement
Frequently Asked Questions
What is the difference between gross and net calorific value?
Gross (HHV) includes the heat recovered by condensing the water formed in combustion; net (LHV) does not. Net is about 10 % lower for natural gas.
Do flow and CV need the same reference conditions?
Yes. Mixing Nm³ (0 °C) flow with an Sm³ (15 °C) CV gives an error of about 5 %.
How many kW is 1 MMBtu/h?
About 293.07 kW.
You May Also Like
Learn more on the blog
Types of flow meters
A practical, field focused guide on instrumentationblog.in that explains the theory behind this calculator and how engineers apply it on real plants.
Read Full ArticleMore Flow Measurement Calculators
Orifice Plate Flow Calculator (ISO 5167)ISO 5167-2, Liquid and gasPipe Flow Velocity CalculatorNPS Sch 40 and 80, Flow to velocityReynolds Number CalculatorLaminar or turbulent, Velocity or flowFlow Meter K Factor CalculatorFrequency to rate, Pulses to totalOrifice Plate Bore Sizing CalculatorISO 5167-2, Bore and β ratioVenturi Tube Flow CalculatorISO 5167-4, Liquid and gasPitot Tube Velocity CalculatorDynamic pressure, VelocityWeir Flow CalculatorV notch, RectangularParshall Flume Flow CalculatorParshall flume, Free flowManning Equation Open Channel CalculatorManning n, Rectangular channelStandard to Actual Gas Flow CalculatorNm³/h, Sm³/hGas Density Calculatorρ = PM/ZRT, Molecular weightMass Flow to Volume Flow Calculatorkg/h to m³/h, m³/h to kg/hPipe Pressure Drop CalculatorDarcy Weisbach, Friction factorFlow Meter Turndown Ratio CalculatorTurndown ratio, DP metersMagnetic Flow Meter Sizing CalculatorDN 10 to DN 600, Velocity checkFlow Meter Straight Pipe Run CalculatorUpstream D, Downstream DFlow Totalizer and Fill Time CalculatorTotal volume, Fill timeFlow Nozzle Flow CalculatorISO 5167-3, ISA 1932Vortex Flow Meter CalculatorStrouhal number, K factorUltrasonic Transit Time Flow CalculatorTransit time, Clamp onRotameter Correction CalculatorVariable area, Liquid densityDP Flow Transmitter Rerange CalculatorSquare root law, Orifice and venturiGas Flow Pressure and Temperature CompensationDP meters, Pressure correctionPipe Sizing Calculator (Flow and Velocity)Flow to diameter, NPS Sch 40 and 80Darcy Friction Factor Calculator (Colebrook)Colebrook White, Swamee JainOrifice Permanent Pressure Loss CalculatorISO 5167-2, Permanent pressure lossTank Drain Time CalculatorTorricelli, Gravity drainPump Power CalculatorHydraulic power, Shaft powerFlow Meter Accuracy Calculator% of rate, % of full scaleRestriction Orifice Sizing CalculatorRestriction orifice, Choked gas flowTank Level Rate to Flow CalculatorLevel change, Net flowFlowmeter Bucket and Stopwatch Test CalculatorBucket test, Meter errorFlow Meter Factor and K Factor Correction CalculatorMeter factor, ProverPump Affinity Laws CalculatorAffinity laws, VFD speedNPSH Available CalculatorNPSHa, NPSHr marginCone (V Cone) Flow Meter CalculatorISO 5167-5, Cone meterAveraging Pitot Tube (Annubar Type) Flow CalculatorAveraging pitot, Flow coefficient KLaminar Flow Element and Capillary Flow CalculatorHagen Poiseuille, CapillaryRectangular Duct Flow and Hydraulic Diameter CalculatorHydraulic diameter, Equivalent diameterPitot Traverse Points and Average Velocity CalculatorLog Tchebycheff, Traverse pointsPartially Full Pipe Flow Calculator (Manning)Manning equation, Gravity sewerDP Flow Measurement Uncertainty Calculator (ISO 5167)ISO 5167-1, Uncertainty budgetGas Pipeline Pressure Drop Calculator (Isothermal)Compressible flow, IsothermalHazen Williams Water Pipe Head Loss CalculatorHazen Williams, C factorErosional Velocity Calculator (API RP 14E)API RP 14E, ErosionPipe Flow Capacity from Pressure Drop CalculatorDarcy Weisbach, Allowable ΔPGas Velocity and Mach Number CalculatorActual velocity, Mach numberChemical Dosing Pump CalculatorDose rate, ppm (mg/L)Flow Rate Unit Converterm³/h, GPM, L/min, CFM
More Calculator Categories
Temperature Measurement26 live toolsInstrumentation Signal13 live toolsPLC Digital Signal12 live toolsLevel Measurement24 live toolsPressure Measurement24 live toolsControl Valve17 live toolsCalibration16 live toolsSafety and SIL16 live toolsAnalytical18 live toolsElectrical37 live toolsElectronics35 live toolsUnit Converters76 converters, 700+ units