There exists a number of performance metrics for different types of processes, particularly for univariate control loops. This paper proposes performance metrics for two-dimensional web-forming processes, that are found in paper, plastic film and steel industries. A simulation example shows that the metrics are able to differentiate between typical disturbance classes. An industrial implementation example demonstrates the use of the metrics as a part of the quality monitoring system of a paper mill. The system currently in use at the mill provides plant personnel with additional quality information that is considerably more detailed than the quality information obtained from laboratory measurements. (C) 2011 Elsevier Ltd. All rights reserved.