Many commercial vendors provide brand valuation measures, which have important practical implications for many stakeholders on how brands are bought and sold and how they are managed. These commercial measures, however, differ to a great extent from one another, which raises serious concerns about their accuracy. In this study, we assess the measurement properties of brand valuation measures provided by the four dominant commercial vendors: Interbrand, Brand Finance, Millward Brown, and Corebrand. We find that the brand valuation measures from the four commercial vendors measure the same underlying construct in a reliable and valid way according to established psychometric test methodology. However, it appears that they measure a construct that does not predict actual brand transaction prices well. In most cases, they significantly overestimate the transaction price. The magnitude of systematic bias varies by method and industry. Our results suggest that an upward bias is more likely to occur in situations when the relevance of tangible assets and non-brand intangible assets is high. These empirical findings challenge current practical and academic thinking on brand valuation. A main conclusion is that brand valuation for transaction purposes needs to first value all assets of the company in their totality and then allocate a fair share to the brand.