GB Gas Rate Calculator (free)

GB-GAS Gas Rate & Heat Input Calculator

A practical gas rate and heat input calculator for gas engineers, trainees and students.

GB-GAS combines traditional manual gas-rate calculations with camera-assisted OCR testing for Metric and Imperial gas meters.

CAMERA-ASSISTED OCR

Use your phone's camera to assist with gas-rate testing.

Metric OCR
Position the meter index within the on-screen guide. The app monitors the changing meter reading and uses a verification system with traffic-light feedback to establish the result.

Imperial OCR
Position the Imperial meter dial within the circular guide. The app tracks movement of the dial pointer to calculate the gas rate.

Camera selection is available on supported devices, allowing you to choose the most suitable rear camera for the meter being tested.

MANUAL GAS RATE CALCULATOR

The Manual Calculator provides a traditional stopwatch-based method for both Metric and Imperial meters.

For Metric meters, enter the start and finish readings and the app calculates consumption using the actual measured test time.

For Imperial meters, time the movement of 1 ft³ of gas.

Every completed test provides:

• Gas Rate – m³/hr
• Heat Input – kW Gross
• Heat Input – kW Net
• Test duration

HIGH FIRE & LOW FIRE TESTING

Enter appliance manufacturer information before testing to compare the measured result with the appliance data.

If only a High Fire value is entered, the app provides a straightforward single-test sequence.

If High Fire and Low Fire values are entered, the app automatically guides you through:

High Fire Test → Low Fire Test → Final Results

The Start button clearly identifies the next test:

START HIGH FIRE TEST
START LOW FIRE TEST

This guided sequence works across all three testing methods:

• Manual Calculator
• Metric OCR
• Imperial OCR

MANUFACTURER COMPARISON

Completed tests can be compared directly with the entered manufacturer information.

The results screen shows the manufacturer value alongside the measured result and calculates the percentage difference, providing clear comparison feedback.

When High Fire and Low Fire tests are required, both results are brought together in the final results display.

TEST DURATION FEEDBACK

The app records the actual test duration and provides feedback where a test is short, helping identify when a longer test may improve the reliability of the measurement.

RESULTS, PRINT & SHARE

The final results display brings together:

• Gas Rate in m³/hr
• Gross Heat Input in kW
• Net Heat Input in kW
• Test duration
• Manufacturer value
• Measured value
• Percentage difference
• High and Low Fire results where applicable

Completed results can be printed or shared directly from the app.

DESIGNED FOR PRACTICAL USE

The interface has been developed around real gas-rate testing, with large controls, camera positioning guides, stopwatch operation, traffic-light verification and clear results.

It is also a useful training aid for students learning gas rating, heat input calculations and the relationship between gas consumption, time and appliance input.

Developed by GB-GAS as a practical calculation and training tool for the gas industry.

Important: This app is intended to assist with calculations and testing. Results must be interpreted by a competent person and used alongside current manufacturer instructions, applicable standards and recognised industry procedures.

Time the Metric meter for two minutes, input the first and second reading, press calculate and your answer is there.
For imperial meters time one revolution then, press calculate and your answer is there.
No more looking up charts or using long winded calculations... Its so simple