Controlling waste rock dilution and ore loss is critical to maximising value from a mine. For new projects, bench height analysis and selective mining unit size (implying size of mining equipment) and their impact on dilution and ore loss, and therefore value, is a critical step in optimising a project. For existing mines, accurately accounting for the dilution and ore loss that will occur during the mining process is important for the accurate forecasting of production. Poor reconciliation between forecast production and production reports is often caused by inaccurate estimation of ore loss and dilution, and can lead to material impacts on project value, in some cases resulting in premature mine closure. For an open pit mine, it is easy to think that ore plus waste creates more ore, but unnecessary waste denies the mine plan significant quantities of lower grade mineralisation that could have been blended into the product stream and used to extend the life of the mine, or can lead to the unnecessary processing of waste that carries negligible value or incurs an economic loss. In AMC Consultants’ (AMC) experience, the estimation of planned dilution and ore loss in both projects and mining operations is often inappropriate. To account for this, global factors are regularly applied as unplanned dilution when reconciliation identifies a variance between the block model estimate and mine production. This approach does not allow for spatial variance in developing the mine or facilitate an understanding of the root causes of poor reconciliation and how they can be addressed. It is always important that the modelling approach of estimating ore loss and dilution reflects the physical mining process that is proposed or is being undertaken. The modelling methods selected need to reflect the size and geometry of the deposit, distribution of mineralisation through the deposit, the size and type of the mining equipment, bench heights, grade control methods, among many others. AMC use a range of approaches for modelling ore loss and dilution for both new projects and existing mines, some of which have been developed in-house and tested extensively over many years, including through production reconciliation. There are times when a simple block regularisation process provides an adequate result and times when more sophisticated techniques are required. But AMC very rarely believes that factoring results from a Mineral Resource block model, which takes little to no account of the issues discussed above, is appropriate. Enhancing dilution and ore loss estimation accuracy allows project developers and operators to better understand the value and opportunity potential of their assets. This paper discusses some of the modelling techniques developed by AMC and their various applications and provides some case studies for mines for which these techniques have been applied.