It's difficult to tell exactly how long wood you've gathered will last you, unless as an expert you can gauge an accurate estimate due to the type of wood, weather conditions and other contributing factors (theoretically possible, but above my ability level.)

However, there are different ways of constructing a fire, and one in particular is designed to burn for long periods, such as overnight, without requiring any maintenance or fiddling about through the night (if done correctly.)

This is known as the pymarid fire:

You place two logs parallel on the ground to start with, then place a row of smaller logs perpendicular and on top of the original two, then another row perpendicular and on top of that row, and so on. You then light the fire at the top, and instinctively quite bizarrely the fire will then burn downwards (as each level becomes hot enough to ignite the layer below it.)

Image taken from here.

It's difficult to tell exactly how long wood you've gathered will last you, unless as an expert you can gauge an accurate estimate due to the type of wood, weather conditions and other contributing factors (theoretically possible, but above my ability level.)

However, there are different ways of constructing a fire, and one in particular is designed to burn for long periods, such as overnight, without requiring any maintenance or fiddling about through the night (if done correctly.)

This is known as a pyramid fire:

You place two logs parallel on the ground to start with, then place a row of smaller logs perpendicular and on top of the original two, then another row perpendicular and on top of that row, and so on. You then light the fire at the top, and instinctively quite bizarrely the fire will then burn downwards (as each level becomes hot enough to ignite the layer below it.)

Image taken from here.