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Artefact · M03 Pressure, flow & measurement

Gas rate and heat input calculator

Time the meter test dial and get the gas rate, then the heat input, gross and net.

Livev1.0.0 · Updated 29 Oct 2026Free sample

Gas rate and heat input

Step 1 of 3

Enter the start reading

Type all eight digits from left to right: five black, then three red.

Test time 2:00

About this tool

Checked by Ryan, October 2026

Enter the meter readings from a timed test and get the gas rate and the gross and net heat input.

A training and checking aid

This tool doesn't replace the current standards, the manufacturer's instructions or your own competence. Always check the result against them before you rely on it.

Sources

  • BS 6891, 2015 (Annex A.2, Table A.1). Calorific value of 38.9 MJ/m³ (gross), the gross to net ratio of about 1.11 (rounded to 1.1), and the worked rates used to check the tool.
  • Gas Safe Register Technical Bulletin 112, 7 December 2017 (Whole bulletin). The two-minute test and how to read electronic and smart meters.
  • Gas Safety (Installation and Use) Regulations 1998, as in force (Regulation 26(9)). Checking operating pressure or heat input, or both, after work on an appliance.

Learn how it works: Lesson 3.5: Gas rate and heat input

Add it to your home screen

On an iPhone or iPad, tap Share, then Add to Home Screen. On Android, open the browser menu and choose Install app or Add to Home screen. It then opens like an app.

While you time the test, the red litre drums on the dial are blurred on purpose. Always read your real meter for the final reading.

Test settings

A standard test is two minutes (120 seconds).

38.9 is the figure BS 6891 uses for natural gas. Only change it if you've been told to.

Countdown beeps

A beep each second for the last 10 seconds, and a long beep at the end.

Data plate rating

From the appliance data plate.

The data plate figure is

The working

Open as a full-page tool you can add to your home screen.

What you're seeing

A calculator built into the site. Enter the meter reading at the start and end of a timed test to get the gas rate in m³/h and the gross and net heat input in kW, with the working shown step by step. It is also available as a free tool you can add to your phone's home screen.

What it shows

  • Timing the meter test dial
  • Converting to a gas rate in m³/h
  • Calculating gross and net heat input