Smarter Heating & Hot Water

Gas Rate Calculator

Calculate gas consumption of appliances to ensure they are within manufacturer and gas safety tolerances.

Meter Start Reading 000
Meter Finish Reading —
Timer Value (Seconds) 60
Gross KW
—
kilowatts
Gross m³/h
—
cubic metres per hour
Net KW
—
kilowatts
Net m³/h
—
cubic metres per hour

Metric Instructions

  1. Ensure that all other gas burning appliances are turned off
  2. Turn on the appliance to be rated to its maximum setting – allow to run for 10 minutes
  3. Take the first reading from the meter (R1)
  4. At exactly 2 minutes take the second reading (R2)

Note: You multiply by 30 because your 2 min read converts to gas units used in 1 hour.

Formula Reference

Gross KW = (((Finish-Start)/1000 × 3600 × 10.76) / Timer)
Gross m³/h = Gross KW / 10.76
Net KW = Gross KW / 1.11
Net m³/h = Gross KW / 10.76 / 1.11
CV = Calorific value 10.76 kW
Factor = Gross to Net factor 1.11

View Metric Gas Rating Chart
Test Dial
Time in Seconds 10
Gross KW
—
kilowatts
Gas Rate m³/h
—
cubic metres per hour
Net KW
—
kilowatts
Net m³/h
—
cubic metres per hour

Imperial Instructions

  1. Ensure that all other gas burning appliances are turned off
  2. Turn on the appliance to be rated to its maximum setting – allow to run for 10 minutes
  3. Time in seconds how long it takes for test dial to complete 1 revolution (1ft³)

Note: ft³ × 0.028 = m³

Formula Reference

Gross KW = (((1×3600×1040)/Time/3412)×Dial)
Gas Rate m³/h = Gross KW / 10.76
Net KW = Gross KW / 1.11
Net m³/h = Gross KW / 10.76 / 1.11
CV = Calorific value 1040 BTU
3412 = Converts BTU to kW
Factor = Gross to Net factor 1.11

View Imperial Gas Rating Chart
Important: This calculator is for indicative purposes only. Always ensure gas appliances are installed, rated, and maintained by Gas Safe registered engineers in accordance with current regulations.