🔥 Plumbing

Gas Appliance Sizing Calculator – Gas Load Calculation & BTU Demand

Free gas appliance sizing calculator: gas load calculation and total BTU/MJ demand for stoves, ovens, geysers and burners. No sign-up.

📐 Standard: IS 6044 / IS 9062
✅ Free to use
📄 PDF export
📱 Mobile friendly
🔥
Gas Appliance Sizing Calculator Calculator
Reference: IS 6044 / IS 9062
🔥 Plumbing
Free gas appliance sizing calculator: gas load calculation and total BTU/MJ demand for stoves, ovens, geysers and burners. No sign-up.
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ℹ️ About This Calculator

The gas appliance sizing calculator aggregates the input ratings of all gas-burning appliances in a building to determine the total connected gas demand. Applying a diversity factor gives the design gas demand, which governs the selection of the gas meter, service regulator, and service pipe size. Per IS 6044 and IS 9062 (gas appliance installation).

IS 9062 covers gas appliance installation requirements. Every gas appliance must be approved by BIS and have the ISI mark. Commercial kitchen appliances are governed by IS 6315. Gas meter sizes (G-rating): G4 = 6 m³/hr; G6 = 10 m³/hr; G10 = 16 m³/hr. Meters are provided by the city gas distribution company. Service regulators maintain downstream pressure at 21 mbar (domestic) regardless of supply pressure variations.

📐 Gas Demand Calculation

IS 6044 / IS 9062

Individual Appliance Demand:
  Q_app (m³/hr) = Input rating (kW) / Calorific value (kWh/m³)
  Natural gas CV ≈ 9.4 kWh/m³; LPG CV ≈ 6.5 kWh/m³ (vapour)

Total Connected Demand:
  Q_total = Σ(Q_app,i)

Design Demand:
  Q_design = Q_total × diversity factor
  Residential diversity: 0.75; Commercial kitchen: 0.85–1.0

Gas Meter Capacity:
  Select meter with Q_max ≥ Q_design
  Residential: G4 (6 m³/hr); commercial: G10, G16, G25 etc.

Service Pipe:
  Sized for Q_design at max 1 mbar pressure drop (low pressure)

🧮 Worked Example

Example: A restaurant kitchen has a 4-burner hot plate (4×4 kW = 16 kW), a 8 kW oven, and a 12 kW tandoor, all on natural gas (CV = 9.4 kWh/m³). Total connected demand Q_total = (16+8+12)/9.4 = 3.83 m³/hr. Applying a commercial kitchen diversity factor of 0.9, design demand Q_design = 3.83 × 0.9 = 3.45 m³/hr. Since this falls within the middle third of a G6 meter (rated to 10 m³/hr), a G6 gas meter is selected, and the service pipe is sized for 3.45 m³/hr at a maximum 1 mbar pressure drop over the kitchen run.

📊 Gas Appliance Loads & Diversity (IS 6044 / IS 9062)

Gas pipe and cylinder banks are sized from the connected appliance load and a diversity factor - not every appliance runs at full rate at once. LPG has a calorific value of about 13.8 kWh/kg (46 MJ/kg), which converts appliance heat input to gas consumption.

Typical LPG Appliance Loads

ApplianceHeat input (kW)Gas rate (kg/h)
Domestic 2-burner stove4 – 70.3 – 0.5
Domestic 4-burner stove8 – 120.6 – 0.9
Instant gas geyser20 – 251.5 – 1.8
Commercial burner (each)14 – 281.0 – 2.0
Commercial griddle / tandoor15 – 301.1 – 2.2

Diversity Factor

For a single domestic kitchen use 1.0 (all burners may be on). For commercial kitchens with many appliances a diversity of 0.6-0.7 is typical, and for multi-dwelling LPG reticulation the factor falls further as the number of flats rises. Apply diversity to the connected load before sizing the pipe and cylinder bank.

Indicative figures - always use the appliance nameplate rating and follow IS 6044 (commercial LPG installations) and PESO requirements for the cylinder bank.

❓ Frequently Asked Questions

What gas input rating should I use for kitchen appliances? +
Typical input ratings: domestic burner (2-burner hob) = 1.5–2.5 kW per burner; hot plate (commercial) = 3–5 kW per burner; gas oven = 5–10 kW; tandoor = 10–15 kW; commercial water heater = 10–24 kW; boiler = 30–500 kW. Use actual appliance nameplate ratings when available. Add 10% margin for unaccounted small appliances.
How is the gas meter size selected? +
Gas meters are rated by their maximum throughput: G4 handles up to 6 m³/hr; G6 up to 10 m³/hr; G10 up to 16 m³/hr; G16 up to 25 m³/hr; G25 up to 40 m³/hr. Select the meter where your design demand falls in the middle third of the meter capacity for accurate measurement (meters are less accurate at very low flows). The city gas company selects and installs the meter.
Is a gas regulator required at every appliance? +
At the building entry: a service regulator reduces supply pressure to 21 mbar (domestic) or higher (commercial). Individual appliances with integral pressure regulators (most modern appliances) do not need additional regulators. Appliances without regulators (some industrial equipment) need an appliance regulator set to the required operating pressure. All flexible connections must be gas-grade hose, not general-purpose rubber.
What happens if I connect more appliances than the gas pipe/meter can supply? +
If the gas pipe is undersized: pressure drops below the minimum at appliances. Effect: yellow/orange flames (incomplete combustion), carbon monoxide production, sooting, poor performance. If the meter is undersized: the meter rotates faster than designed, inaccurate billing, potential meter damage. Always size the service pipe and meter for the maximum expected simultaneous demand.
Do I need special ventilation for gas appliances? +
Yes, per IS 9062: open-flued appliances (type B) need combustion air supply (minimum 2 cm² free area per kW of appliance rating) and a flue vent to the outside. Room-sealed appliances (type C) draw air and discharge flue gases directly through the external wall – no room ventilation required. All gas appliances in enclosed kitchens must have CO detectors per BIS 2016 amendment. LPG appliances need low-level ventilation; PNG appliances need high-level vents.
How do I calculate LPG demand for a commercial kitchen? +
Add the heat input of every gas appliance, convert to a gas rate using the LPG calorific value (about 13.8 kWh/kg), then apply a diversity factor of roughly 0.6-0.7 because not all appliances fire simultaneously. The result sizes the pipe and cylinder-bank vaporisation capacity.
What is diversity factor in gas pipe sizing? +
It is the fraction of the total connected appliance load that is likely to be drawn at the same time. A single home kitchen uses 1.0, a busy commercial kitchen about 0.6-0.7, and large reticulated LPG systems even less. It prevents over-sizing the supply for a peak that never occurs.
What is the difference between IS 6044 and IS 9062? +
IS 6044 covers the design and installation of commercial LPG installations (kitchens, cylinder banks, pipework), while IS 9062 relates to LPG cylinder manifolds and fittings. Together they govern appliance loads, diversity and safe pipe and manifold sizing for Indian commercial gas systems.

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