Cost-per-thousand is a way in which cost-efficiency can be expressed. It is a measure of audience delivered per unit of cost (eg a TV spot costing £1000 seen by 100,000 housewives delivers a cost-per-thousand of £1000/100 = £10.00). It is typically used in inter- or intra-media comparisons of cost-efficiency (usually abbreviated to 'cpt' - 'cpm' in some countries). Audiences may be general (eg 'All housewives') or highly specific (eg 'C1C2 males aged 15-44 who are regular readers of the Daily Telegraph').
the cost of reaching a thousand people in the target market. Used comparatively to measure different media and schedules.
A figure used in comparing or evaluating the cost efficiency of media vehicles. CPM is the cost to deliver 1,000 people or homes and is calculated by dividing the cost by the audience delivery and multiplying the quotient by 1,000.