The ease of working out the quantity of flooring you need is really dependant on the layout of your room. Rectangular rooms can be calculated easily by multiplying the length by width (see example 1).
However if your room is L-shaped, or has alcoves or bay windows then things do become a little more tricky. You need to divide your room into separate smaller areas, adding these together to come to your final quantity (see example 2 and example 3).
Don’t forget to add at least 10% to your final quantity for any wastage that comes from trimming and awkward layouts. The more complex your room layout the more wastage you will produce so remember to accommodate for this with a little extra.