Purpose – This paper aims to present a supply chain performance assessment tool that measures the performance of key supply chain activities of a firm under different performance dimensions. Design/methodology/approach – The tool was developed based on an extensive literature review. The nine key internal supply chain activities, as proposed by Grant et al. in 2006, constituted the backbone of the assessment framework, while performance was measured based on three dimensions: cost, time, and reliability. The tool was pilot-tested on 44 local SMEs. The results were then compared with existing performance benchmark as well as within the benchmarked group itself and a high performing Thai multinational in order to see whether the developed tool could identify performance gaps in the trial group. Findings – The results obtained from the tool provide a description of a firm's internal supply chain activity. The utilised supply chain performance framework can isolate each individual supply chain activity. The results are therefore precise enough for firms to identify individual areas of strengths and weaknesses. The tool is relatively simple and easy to use and understand. Research limitations/implications – Limitation is related to the availability of the required assessment data. The availability of data is a reflection of systematic data collection and storage procedures of the respondent firms. Originality/value – The tool was developed on clearly defined theoretical foundations. The three dimensions of cost, time and reliability can balance both financial and non-financial characteristics of supply chain performance. The data required are simple and objective.