The volume of childcare output is measured in hours of childcare required. This is calculated by subtracting hours spent in formal childcare from the total number of hours for which care is needed. The latter is the population under 16 multiplied by 24 hours per day and 365 days per year, with an adjustment for the unsupervised time of older children. The sources of information for this estimate are the ONS mid-year population estimates and a mixture of administrative and survey data. Information on formal childcare places in England comes from the Department for Education and Skills and the Department of Health. It comes from the constituent country administrations for the rest of the UK. This data includes numbers of children in school, with childminders, in nurseries, in playgroups, in children's homes, with foster parents, in hospitals, and attending holiday and out-of-school clubs. Information on the number of nannies comes from the Labour Force Survey and information on the number of children in independent schools comes from the Independent School Census conducted by ISIS. Assumptions about the amount of time spent in formal places are based on the childcare module in the Family Resource Survey (FRS) and the DfES publication "Children's Day Care Facilities".

For further details, see Chapter 6 of the HHSA methodology (downloads).  See Sensitivity Analysis for results using alternative assumptions about time spent unsupervised.