The thermal conductivity of the lower mantle plays a major role in shaping the structure and dynamics of the region. However, the thermal conductivity of lower mantle minerals are, at present, not well constrained, because of difficulties in making measurements at such high pressures. Here we describe the most common theoretical methods available to calculate the thermal conductivity of materials, which provide an invaluable alternative to experimental techniques. In each case the general scheme is given and particular considerations highlighted. The advantages and disadvantages and applicability of the methods are then discussed. We conclude with a short review of theoretical studies of the lattice thermal conductivity of periclase.