Folks,

In the process of installing a new boiler, but am not really sure how I
should calculate the gas pipe size to the boiler.

The gas meter is just under 5 meters away (as the pipes will run) and this
will be the only gas appliance in the house (the Kitchen is the opposite
direction to the boiler too, so if any gas is needed or there, it won't need
to branch off of the run the the boiler)

Can someone possibly help me understand how to calculate this!?

(There will need to be two bends in the pipe, I assume swept bends are going
to be preferable here?)

Many thanks!