Agricultural stakeholders are in need of a common set of metrics to evaluate plant pests. We propose a classification system that articulates, defines and classifies the impacts of pest species (alien and native) in plant production systems. Criteria were defined by magnitude of impact (historical, current or potential), with a focus on production specific metrics. Metrics were identified and criteria defined through consideration of economic assessment parameters, risk assessment guidance tools, discussions with pest risk assessment practitioners and recent advances in environmental impact classification schemes. Twenty metrics were identified. Host crop value, market access, feasibility of management and reversibility were identified as disruptor metrics, likely to influence overall classification by at least twice that of other metrics. Utility of the metric system is explored through application to Australian and New Zealand plant pests. The system has been designed to facilitate transparency, flexibility (in development and application) and harmonisation of pest management and prioritisation across spatial scales and jurisdictions.