Essential HeatingServices Limited

THE ESSENTIAL ENGINEER TOOLKIT

Gas rate
calculator.

Meter readings in.
Clear calculations out.

Calculate gas rate and gross and net heat input from your timed meter test. In your browser, ready when you are.

Free to useNo account neededMetric & imperial

01 / YOUR TEST

METRIC · m³
Gas type
Meter method

Enter the full meter readings, including the decimal digits used for the test.

Use the actual elapsed time, including any extra seconds needed to read the meter.

COUNTDOWN / 2 MIN
02:00.0

Or enter a measured time above. No timer is required.

Gas values & calculation settings

Natural gas reference: gross CV 38.76 MJ/m³ and gross-to-net ratio 1.11. Replace these with the values applicable to the gas supplied.

Heat input is calculated from timed volume and the displayed gas values. This is not a gas-billing calculation; no billing volume-correction factor is applied.

KEEP YOUR PLACE

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Your last 10 calculations in this tab. They are not saved to your account or retained when this page closes.

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    BEHIND THE NUMBERS

    Clear method.
    Visible assumptions.

    Need the IGEM/UP/1B Calculator?
    How is gas rate calculated?

    The timed volume in cubic metres is multiplied by 3,600 and divided by the actual test time in seconds. Gross heat input is gas rate × gross calorific value ÷ 3.6. Net heat input is gross heat input ÷ the selected gross-to-net ratio.

    What do I enter for an imperial meter?

    Use the volume marked on the test dial and time the complete revolutions you enter. The default is one cubic foot per revolution; check the dial on the meter. The large meter index can be in hundreds of cubic feet and is not the same as the test-dial volume. One cubic foot is converted to 0.028316846592 m³.

    Which gas values are used?

    Natural gas starts at 38.76 MJ/m³ gross and a 1.11 gross-to-net ratio, following Worcester Bosch’s gas-rating bulletin. Propane uses G31 reference values of 95.65 MJ/m³ gross and 88 MJ/m³ net. LPG blends and supplied gas values vary. Open the gas-value settings to enter the applicable supplier or manufacturer values.

    Does the timer stop at two minutes?

    The metric timer counts down, then continues to show any extra elapsed time. Stop it when you take the final reading. The stopped elapsed time is used in the calculation. Imperial mode uses a stopwatch. Keep this page open and verify your timing; you can always type the actual time manually.

    Is this the IGEM/UP/1B Calculator?

    No. Gas rating measures fuel consumption and heat input. The separate IGEM/UP/1B Calculator handles gas tightness testing and installation volume. Both are Essential engineer tools.

    Technical references: Worcester Bosch TB 0105 b · IPSO / Alliance CE gas properties (G31). Follow the current appliance instructions and applicable gas procedures.