Use fill rate in a sentence. Show more usage examples... The t-shirt company had enough blue t-shirts in stock to perform a twenty-five percent fill rate for their customers, and the remaining back orders had to be fulfilled by a new manufacturing order from the factory in China. 5 people found this helpful. The fill rate of the item was good and we were ready to begin the next part of the process and we were happy.  The company prides itself on maintaining an on time order fill rate of 99.9% as a main driver behind its customer retention rate.