Achieving sustainability -the balance between economic and social development and environmental viability -is one of the key goals of industry, society and government. To measure sustainability, numerous indicators or "metrics" have been developed. However, they do not typically incorporate any information about a local region: they relate equally to a power station in Antarctica or in the middle of the Amazon rainforest. This paper describes a new approach to sustainability metrics that brings local conditions into the assessment of sustainability. We introduce a general mathematical and theoretical model for deriving such metrics and then demonstrate on one specific metric -soil acidification -that provides a useful and well known example. The metrics are applied to differentiate between four sites for the same power station in Australia. The methodology demonstrates a marked difference to existing sustainability metrics, in that it is able to distinguish between different receiving environments, something that cannot be achieved with previously described sets of metrics. These "location-specific sustainability metrics" offer a model to improve the information upon which decisions about future development strategies are made, and to evaluate sustainability in a way that better represents the real world.