This is a Quora questions that I was asked to answer. Here is my answer.
That will depend on a lot of factors – your volume, distances, consistency, speed of delivery, does the product require cooling, how is it packaged (case and pallet configurations), carrier, etc.
For 8+ figures in annual sales, I have gotten that number down to as low as 5% of revenue.
For a small 6-figure company, I have run as high as 15% of revenue.
So, figure 15% on the high end for low volume and 5% on the low end for high volume.