Actual gas bill:

3 September 2017 7650 Estimate

4 September 2017 7665 Read

1 October 2017 7696 Read

Meter units used: 46

Energy* 517 kWh @ 2.35 p/kWh £ 12.16

My calculations using your formulas:

Meter units used 46

Volume conversion factor x 1.00

Metric units = 46

Volume correction x 1.02264 = 47.04

Calorific value x 39.3 = 1848.67

Convert to kWh ÷ 3.6 = 513.52

Energy used 513 kWh

Energy 513 kWh @ 2.35 = £12.05

This is showing a discrepancy of 4 kWh (11p)

Can you explain or correct my calculation.

On another point:

Last month an estimate was used which gave an elec reading of 123.3kWh used, although my bill this month reads 223 kWh used, is this bill calculated on 222.7kWh in other words has the .3kWh been taken in to account?