The long-term economic viability of offshore wind power is not only reliant on reducing installation, commissioning, and operations and maintenance costs, but also on the elimination of subsidies and grants. Current economic analyses use historical price and cost data to predict the levelised cost, net present value, payback period and internal rate of return from offshore wind. These analyses use parameters such as water depth at site, number and size of turbines, grid connection costs, equipment costs, revenue from the wholesale market price of electricity, operations and maintenance costs, revenue from subsidies and the cost of finance amongst others to build a model to determine the viability of the array. Here we review the challenges of accurately estimating levelised cost of energy (LCOE) for offshore wind outlining differing approaches to calculating LCOE, the factors influencing this, and the impact of variation in LCOE calculation. Current costs for the production of offshore wind energy are summarised based on publicly available datasets.