When you plan for a new floor of any kind you are inevitably going to need to talk
about "waste" The trouble is the very idea of order extra flooring which costing more money only to throw it way seems crazy. However, Im sorry to say when ordering flooring waste is unavoidable and absolutely something you should plan for.
Waste is primarily the result of cutting your floor to fit your room. To add some good news most of your cuts will be usable elsewhere in the room but as sure as death and taxes waste will be a factor.
Another aspect to consider is real wood flooring does have natural knots, graining patterns and some boards may not pass your own visual inspection. For example rustic grade floors will have more imperfections therefore you may wish to consider more the waste.
Another factor that should be considered is the availability of your flooring in future years to come. You may need to repair your floor or even extend.
I cannot tell you how often someone needs an extra meter or two to complete their floor which in the end costs more because they didn't buy enough to begin with. So planning in waste is not wasteful its part of the planning and preparation a wise DIYer considers ahead of time.
5% waste is considered normal but be aware someone who is extra careful, installing in a simply layout room might only need 2% but another DIY who isnt as careful and is installing in a complicated room with lots of doorways may use 10%.